Yes, there are shortages and the system is expensive. But fees would not fix it, says Francoise Shenfield

Simon Jenkins argues for market criteria to be applied to egg donation (In the name of purity, public funds are wasted on the rich, 25 August). Britain's regulator in this field, the Human Fertilisation and Embryology Authority, will soon rule on the issue of compensation to egg donors.

Jenkins raises interesting points, in particular: "If we do not pay what the market requires, we will get shortage, profiteering and unfairness." But two important points should be made in the face of his pragmatic market approach – advocating a deregulated payment to donors to increase numbers – and his hatred of "money–loathing", which he says is "rife in the British public service".

First, other factors such as the ending of donors' anonymity may also be relevant to the shortage, as shown by the only European study published to date, by the European Society of Human Reproduction and Embryology. And when, as Jenkins points out, "couples travel to Spain" and other countries in search of donors, it may also be because they prefer anonymity. It may be easier to recruit anonymous donors too.

Second, as a former member of the HFEA like Jenkins, I do not need to remind him that payment is not only illegal in the UK, but would also fall foul of European regulations on tissues and other human cells like eggs and sperm. When he mentions "compensation" it is merely to ridicule the principle and the time spent by the regulators to fathom what is proportionate and fair on reimbursing for travel, time, etc.

But I agree with him that allowing couples undergoing IVF to "give" some of their own eggs in exchange for cheaper private treatment is a disproportionate form of compensation which may be seen as actual payment.

The dearth of oocytes lies elsewhere. We need better informed campaigns about this specific treatment – more likely to be needed for women recovering from cancer or struck by a premature menopause than for the very few over-60s who make the headlines.

Jenkins continues to criticise his then female fellow regulators (like myself): "Most colleagues on the authority at the time, notably the women, refused to make any decision with the taint of filthy lucre." But as a woman, and surely also like many men, I am concerned by what message we transmit to future generations. Can everything, including their "origins", be bought? My personal (female) answer is no.

Ultimately, the UK's "exclusive and expensive" IVF market bemoaned by Jenkins is the result of a lack of NHS access, and has little to do with over-regulation. In this field many people – both patients and generous donors – are at risk of abuse, especially if inflated prices effectively mean they cannot give appropriate consent to a decision which involves future children. At ESHRE, we hope we can maintain international standards with a code of practice, which is preferable to hard regulations. Our patients need just and fair access; and the generous donors need fair compensation, but not disproportionate fees.

Number of deaths and attempted deaths on the railways rose from 236 in 2009 to 2010, compared to 215 in the previous 12 months, say Network Rail

Suicides and suspected suicides on the national rail network increased by 10% last year, according to figures released to coincide with a new, five-year Samaritans campaign to reduce male suicide across the UK.

Launched today, the Men on the Ropes campaign specifically targets working-class men in their 30s to 50s, the group most likely of all men to die by suicide.

"Our research into this target group found that men from poorer backgrounds, those who are unemployed or in manual jobs and those who have experienced difficult times such as financial worries or breakdowns in their family relationships were more likely to take their own lives," said Rachel Kirby-Rider of the Samaritans.

Around 6,000 people in the UK take their own lives every year, three-quarters of whom are men. Of these, the most likely to die by suicide are aged 25 to 55.

According to figures released by Network Rail, the Am.

Welsh International rugby union referee Nigel Owens, of Pontyberem, who attempted to take his own life, is supporting the campaign.

"Men from my town would just get on with things, you weren't even aware men had problems. My depression started because I didn't like who I was and I was too ashamed to talk to anyone," he said. "I let these feelings build up and up, and before I knew it I couldn't see a reason to live any more, which is why I tried to take my own life.

"Looking back there were people I could have and should have turned to. I think that if I had been able to talk to someone that day, I might not have attempted suicide. Today, I can't even find the words to explain how thankful I am that I am still here," he added. "That's why this campaign is so important; because it has the power to make men aware help is available and that they should use it."

Network Rail has pledged to reduce railway suicides by 20%. The company is backing The Samaritans by donating advertising space for the campaign in railway stations across Great Britain.

The Samaritans commissioned research in Glasgow, Middlesbrough, Romford and Solihull, and spoke in detail to a sample group of men about their lives and the daily challenges they face.

"We found that this group of men do not habitually discuss their emotions in public and certainly not with their friends," said Kirby-Rider. "They openly acknowledged that there was a sense in their neighbourhood that a man talking about his problems would be seen as 'weak'."

Many of the men the Samaritans spoke to admitted to having long-term depression as a result of extended periods of unemployment, family breakdown, drug and gambling problems and a sense that things would not get any better.

Many men, added Kirby-Rider, described themselves as leading "emasculated" lives: unable to find work, dependent on their partner's income, and "reduced" to being a househusband.

"Over their lives, most have had experience of being regularly laid-off and of frequently changing jobs and employer," she added.

The Samaritans can be contacted 24 hours a day on 08457 90 90 90.

Health tourists travel the world and spend thousands, but their hopes of being cured are likely to be dashed

For the past decade stem cells have sparked huge excitement among scientists, dramatic media coverage about breakthroughs that could mean a cure for some of the nastiest diseases, and hope – sometimes desperate – among patients that the reality will match the hype. That has fuelled a booming trade in stem cell tourism – people heading to clinics abroad and forking out large sums for what are called stem cell treatments but which are unlikely to work and possibly do harm.

It is, as some of the UK's leading stem cells experts warned last week, a world of unproven therapies, patient optimism and predatory clinicians. Despite the lack of reliable evidence underpinning the treatments being offered, the number of people resorting to stem cell tourism is growing. Experts voiced their fears and frustrations after finding that many patients, often desperately ill, were asking their advice on whether to travel overseas.

"I've made some very strong comments which could potentially land me in court, but people still go to these clinics," said Professor Peter Coffey, director of the London Project to Cure Blindness at University College London. There are now several hundred clinics around the world which claim to have turned the potential of stem cells into effective treatments. They lure those suffering from diabetes, multiple sclerosis, heart failure, Parkinson's disease, autism, HIV, eye problems, spinal cord injuries and much else besides.

Several thousand people from around the world so far are estimated to have spent up to £20,000 or more in such places. Yet while stem cells could transform medicine, there is as yet scant actual proof of their efficacy. But still the tourists come.

The fact that scientists believe it is likely to be 15 to 20 years before the continuing worldwide flurry of trials and tests results in reliable treatments has not stopped clinics from offering exactly that already. Strong regulation means there are no such places in the UK or America. But the experts did single out the XCell Centre in Düsseldorf, Germany, and Beike Technology, which runs one in Shenzhen in China.

In 2008 the Multiple Sclerosis Society warned sufferers not to be taken in by Integrated BioSciences, a company registered in the Turks & Caicos Islands, which had offices in the Seychelles, Persian Gulf and Oxford, because there was no scientific backing for the claim that stem cells could cure the condition.

People's willingness to trust their savings and their health to such clinics recently prompted the International Society for Stem Cell Research to launch a website to educate patients about the risks involved. Anyone thinking about going would be well advised to check it out and think again.

Voyeuristic, sensationalist, revolting… Embarrassing Bodies is accused of being all of these. So why are people prepared to share their unsightly medical problems with a record-breaking TV audience?

A sweaty morning at Thorpe Park, and the smell of sunblock and ketchup hangs heavy in the air. In the shade of Saw, a freefall rollercoaster based on the torture-porn franchise, and beside a grey but warming lake, a crowd is gathering by the Embarrassing Bodies truck. For one day only, Dr Christian Jessen and Dr Dawn Harper will be consulting in the back of their well-lit van, a televised surgery open to anybody passing between rides. Provided, of course, that they're within the 70% of the population suffering from an embarrassing illness – varicose veins, excess hair, stretchmarks, alopecia, IBS, obesity. Something that oozes, preferably. Something swollen.

Rosie and Kelly are 13 years old, and so excited to be in the presence of Dr Christian that they're quivering, visibly. As fans of Embarrassing Bodies, the Channel 4 show that offers contributors lengthy medical attention in exchange for a close-up of their glittering piles, they're recalling their favourite episode from the three series so far. Was it the episode with the interior designer's oversized labia? Was it the one about the woman with the udder-like breasts? The one with Christina's anal warts? They remember all of those, but their favourite was the episode where Dr Christian stood in a locker room to compare the penis sizes of a whole rugby team. "It was brilliant," they say. "He was brilliant. I'd definitely go on the show, if I had something wrong." Then I ask Rosie and Kelly, as I will ask many people over the next few days, the question most asked about Embarrassing Bodies: if the problem embarrasses them, why do patients choose to go on telly with it? They answer, but I'll come to that.

Embarrassing Bodies, produced by Maverick TV, first appeared on Channel 4 in 2007, an explosion of incontinence and skin rashes, with Ashley Jensen's voiceover explaining the statistics around the illnesses shown. In the Evening Standard, Victor Lewis-Smith wrote that the show was "admirable, unpalatable, fascinating and repulsive in roughly equal measure". Since then it's become furiously successful, the most watched programme on Channel 4 this year, consistently winning audiences of up to four million, double the average ratings for its 9pm time slot.

The show has covered 120 different conditions to date. After last month's special episode, about a nine-year-old girl called Charlotte who visited the clinic with extreme verrucas – her feet were covered in molluscs – and was found to need a bone marrow transplant, the Anthony Nolan Trust reported a 4,000% increase in enquiries. Embarrassing Bodies's Bafta-award-winning website is responsible for 42% of Channel 4's web traffic, and its STI checker has, at last count, been used by one million people. More than 150,000 viewers took their online autism spectrum test, creating the world's largest test of its kind.

The website is also used as an example of how television is moving towards a "multiplatform" future – spikes in Embarrassing Bodies's web traffic during the show proved viewers are watching with their laptops open, tapping their own questions into the message boards, clicking through the "vulva gallery" or applying to be on the show. Adam Gee, cross-platform commissioning editor for factual programming at Channel 4, explains, "It was the first evidence that multiplatform for factual could work and find an audience."

Along with Drs Dawn Harper and Pixie McKenna, Dr Christian Jessen is the face of Embarrassing Bodies. The face, the arms, the muscular chest, the skin of which can often be seen peeking from a carelessly buttoned polo shirt, the colour of cured meat and the size of a healthy bottom. We meet as he comes off the rollercoaster Colossus, where he's been testing his heart rate for a piece about stress levels. He happily poses for photographs for fans and gives me an apologetic grin as he signs another autograph.

Last year Jessen hit the headlines when Gordon Brown's spin doctor, Damian McBride, sent an email to Labour blogger Derek Draper, suggesting they spread the unfounded story that David Cameron had suffered from a sexually transmitted disease. He also suggested "inserting picture of Dr Christian Jessen", implying the Embarrassing Bodies doctor, also a practising Harley Street GP, had treated the now Prime Minister.

"I can't say I've never met David Cameron," Jessen said at the time, also unable to deny it. "It's interesting, because if you say, 'No, someone's not a patient', is that also a breach of confidentiality?" His main gripe with the story, he said, was the suggestion that treatment for an STI could have brought down a government. "I was particularly disappointed because there I am, slogging away, trying to make people feel more comfortable talking about these things, and then this idiot undoes it all in one email by implying it is shameful and embarrassing. It made me very cross."

Jessen is very posh, very clever and very charming. He grew up in Fulham, west London, went to boarding school and graduated from UCL in 2000, when he moved to Kenya and Uganda to research HIV and malaria in children. Now 32, he lives with his partner and miniature Pinscher in London.

When he joined the show, he didn't think it would last. "I didn't think piles and verrucas would be exciting to a Channel 4 audience," he says, "but I soon realised that people hadn't seen the novelty of haemorrhoids before, because we're usually pretty crap about talking about this stuff. Yes it's a bit gross, but we never treat it in a sensationalistic way. It's good, practical telly, and that's why it works." I can't help but comment on his muscles. They're glinting in the sunlight, swelling like hams in my sightline. He thanks me. "I like it when people think I don't look like a doctor – that's why we were cast. We're not bow-tied, spectacled, dull. There's a need for normal-looking people in the medical profession I think, a crying need for doctors who are approachable." On screen, they're referred to as Dr Christian, Dr Dawn. "It's a very closed business, very secretive and reverential. And our harshest critics are other doctors."

Dr Dee Dawson, medical director of the Rhodes Farm eating disorder clinic, has watched Embarrassing Bodies from her London sofa. She says the show "sensationalises serious illnesses and pleases ghoulish audiences with its tabloid format". But, she continues, "in doing that, it also alerts them to potential problems, and I'm sure people are more likely to see their doctors after watching an episode relevant to them, in the same way that we saw a spike in smear tests after Jade Goody talked about her cervical cancer. It's horrendous," she says, "and so overly dramatic, but it's a positive thing, in the end. In fact, my father only had a melanoma diagnosed after watching a medical programme on TV."

Inside the Embarrassing Bodies truck, a screen separates the surgery set and a tiny waiting room, where a bowl of pink orchids erupts on the coffee table. The first patient to walk in from the park is 23-year-old Natasha, who wants to talk about irritable bowel syndrome. Her boyfriend, Peter, waits patiently by the fence. "We love the show," he tells me. "My mother died of skin cancer this year and the programme showed me the warning signs to look out for. Plus all the blokes with their tackle out – they ask questions I wouldn't dare!"

As the cameras roll, Dr Christian asks Natasha about her loose stools. "The message," he says, after a brief conversation, "is don't panic, but be insistent. Fight for help, and find a GP that will ask for more tests."

Outside in the sunshine Natasha is elated. "That was so fantastic," she says. "He gave me the confidence to go back to my doctor. And yes, it's an embarrassing problem, but when you finally talk about it you feel so much better."

Why did you decide to go on TV with it?

"Well," she says, "I love

the show. And I love that the doctors make themselves so approachable. GPs, usually, are so busy they don't have time to listen. And I honestly think the show is changing young people's views on how they communicate about their bodies."

Rosie and Kelly, still lurking for another glimpse of Dr Christian, agree. They say that their friends wouldn't laugh at them if they appeared on Embarrassing Bodies because the fact it's on TV legitimises the problem – takes the shame away.

Dr Dawn Harper, who's an NHS GP in Gloucestershire when not filming, says one of the reasons people decide to take their problems on the show is the brand recognition. "They've seen us on TV, so they trust us. Plus, there's a huge sector of society that thinks: 'If it's not life threatening, I mustn't bother my doctor', or they've felt a lack of sympathy from them in the past. And while women are always registered with the doctor for their smear test, men are often still registered at their mum's GP. Viewers feel like they know us a bit. They've seen how we interact with patients so they know what to expect. And we have support from more and more specialists as the show grows, so there's the availability of things that aren't offered on the NHS."

I hear all Harper's reasons repeated by patients as the day goes on.

Kelly Coulter, who's brought her 18-month-old son to the truckstop to talk about a problem with his gums, says she'd "absolutely get my breasts out on the show if I was guaranteed a boob job". Plastic surgery is a subject often broached in the programme. Jessen (who talked to the Daily Mail about his hair transplant in May) tells me, "I'm for plastic surgery, as long as the industry doesn't take advantage and prey on us."

One of the surgeries Jessen recommended on an episode in 2008 was a patient's labioplasty. In her book Living Dolls, Natasha Walter details how uneasy this made her feel. "[In this episode] a young woman consulted a doctor about the fact that her labia minora extended slightly beyond her labia majora and that this caused her embarrassment. Instead of reassuring her that this was entirely normal, the doctor recommended, and carried out, surgery on her labia. The comments left on the programme's website showed how this decision to carry out plastic surgery to fit a young woman's body to a so-called norm made other young women feel intensely anxious. 'I'm 15 and I thought I was fine, but since I've watched the programme I've become worried, as mine seem larger than the girl who had hers made surgically smaller! It doesn't make any difference to my life, but I worry now that when I'm older and start having sex I might have problems!' one girl said.

"This idea that there is one correct way for female genitals to look is undoubtedly tied into the rise of pornography… If the rise of pornography was really tied up with women's liberation and empowerment, it would not be increasing women's anxiety about fitting into a narrow physical ideal," wrote Walter.

I ask Jessen whether this patient's referral was a difficult decision. "It's a hugely controversial subject, but she was having dreams about cutting off her labia. To me, that justifies the treatment – she was grossly psychologically disturbed." Is he concerned that with this decision he might encourage female viewers to seek surgery when there's no medical problem? He sighs. "It's our job to show all available treatment. And if it creates a forum for girls to talk about their bodies… We try our best – there's no malice in what we do."

A few days later, in their Birmingham clinic/studio, a set lit so whitely it feels like a 1960s vision of heaven, I meet John. I'd heard about John. Once, over lunch, a friend told me about the programme she'd watched the night before. Wide-eyed, she used her hands to describe an operation they'd shown, where, in order to cure the man's perianal abscesses, they'd stretched his anus open with metal pegs, so that, square, it filled the TV screen neatly. The image stays with her still. When John, now 27, returns to Embarrassing Bodies, it's after 15 operations; he says he's feeling "the best I have in four years".

The problem began when he was 23, and a prison officer in Nottingham. One night, an inmate threw a television from the floor above – it landed inches from where John was standing and he had a panic attack. He took a week off due to stress and it was then that he noticed the first swelling. When the abscess burst inside him, it spread. The pain, he says, was like "being kicked in the spine", and once it caused him to black out. But worse than the pain, he says, was the humiliation of asking his girlfriend, who he'd met while recovering from his eighth operation, to regularly clean his seeping wounds. "He'd had to wear a nappy in his pants," Dr Pixie McKenna tells me. "It was so, so sad."

The episode of Embarrassing Bodies which concentrated on Charlotte Wilson's verrucas inspired John to seek them out – John chased their truck stops around Britain, finally getting a walk-in appointment with Dr Pixie when he'd just come off a night shift.

"I saw that they'd saved that little girl's life, so I wanted them to fight my corner," John tells me. "And I thought if they could help me out, then showing my backside on national TV would be a small price to pay." When John's episode aired, he found out later, his prison colleagues had thrown an Embarrassing Bodies party, where, during the screening of his operation, someone had thrown up on their pepperoni pizza.

Today, after shyly admitting that his girlfriend has agreed to marry him, he's happy to drop his trousers and show his scars to Dr Pixie, who gasps with pleasure. "That is not the same bottom that I first met!" she cries.

Michelle, 45, is birdlike, and woke at five to drive down from Lancaster, where she's proud to live in an Area of Outstanding Natural Beauty. When she told her 19-year-old son she was thinking of approaching Embarrassing Bodies about her constipation after a post- hysterectomy prolapse, he said he wasn't happy about it, but that if it would help, he'd support her. Sitting in the surgery, camera angles mean she must answer Dr Pixie's question – "Do you get any soiling?" four times. Her examination is over in seconds – a rectocele is diagnosed – and the screen where I'm sitting fills with an internal HD image. "Embarrassing Bodies doesn't believe in pixilation," the executive producer, Steph Harris, tells me. "It implies shame."

I talk to Michelle over a cup of tea. "I was very apprehensive, yes," she says. She's sitting up straighter than she was before she entered the surgery – she seems to take up more space, somehow. "I was especially scared about the young cameraman, but he made me feel completely at ease. There was no pressure and lots of explanation. I'm so happy to have come."

But why choose to broadcast your problem, I ask. "I come from a nursing background and this is one of my favourite shows, so I knew I'd get an honest consultation. And if nothing else, I wanted to highlight how common this problem is to other women. I'm not the only one of my friends to watch it either – I have a friend who's in hospital today after diagnosing herself with carpal tunnel syndrome when she saw it on the programme."

For all the reviews pointing out Embarrassing Bodies's "crypto-pornographic nature", the criticism of the show's relationships with cosmetic surgeons, and the format, which relies on suspenseful ad breaks and the promise of genital close-ups, it's the patients who convince me that the programme does good, helping viewers talk about worries they'd otherwise hide.

Dr Dawn tells me about a recent event she went to with her NHS colleagues. "They tease me, of course they do, but that night 40 out of the 60 doctors there told me they'd seen patients purely off the back of the show."

Interestingly, I think this is the only show in the makeover genre to include both male and female contributors. And while the occasional woman's saggy belly is hacked away by surgeons, the overall message is one of practical medicine: less about how you feel about your body, more about the body itself. And it's the only programme on telly where the haemorrhoid's the star.

Embarrassing Bodies series four begins on C4 on 17 September. Can I Just Ask? (Hay House, £12.99) by Dr Christian Jessen, a collection of questions doctors are asked when off-duty, is published on 1 November

Charlotte's story
The case which turned the show into a national treasure

In the autumn of 2008, nine-year-old Charlotte Wilson's mother, Sofia, led her into Dr Christian's clinic, seeking help for her verrucas. When he saw her feet, he was briefly speechless, but viewers saw his brain whirring into action. Verrucas, a common viral infection which most people's immune systems can quickly defeat, covered her toes in a terrifying crust. Dr Christian realised that this was an indication that Charlotte's immune system was losing the battle. She was referred to Great Ormond Street Hospital where the diagnosis was confirmed. The immunologist warned that in time Charlotte would be vulnerable to life-threatening infections. She needed a bone marrow transplant. Luckily, blood tests revealed that her sister Isabelle was a perfect match. Charlotte received chemotherapy in an isolation room, and after months away from home, she celebrated her 10th birthday in hospital, waiting for the bone marrow to take root.

When the show aired, the Embarrassing Bodies website encouraged viewers to sign up for the Bone Marrow Register and the following day the Anthony Nolan Trust received 1,400 requests for information, as opposed to the usual 30. This week, the show's producer received an email from Sofia Wilson. "Charlotte looks fantastic," wrote her mother. "Lots of curly hair and a suntan... is going to take longer than we thought (Charlotte has to learn to stick a needle under her skin so that she can do her gamma-globulin infusion herself), but you saved our daughter's life".

'I soon learned never to express hunger around them and to eat in secret, thereby developing an inextricable emotional link between what I ate and my ability to be loved'

In my head I am thin. I just haven't quite got there yet. As I was growing up, it was made clear that the fat me wasn't welcome, that a thin person was expected and awaited, and impatiently so. Of my parents' four children, I was always known as the "fat one". They had longed for a girl, following two boys born in quick succession, and were thrilled when I finally arrived. As I well know, having longed for a daughter myself, when one dreams of having a girl one does not picture a fat one – no one does. Hopeful parents picture a sweet, pretty (regrettable, but true), adorable little thing who'll be cuddly and affectionate in the way boys, post-babyhood, are rarely expected to be.

As retold by my parents, their close friends and relatives, for the first few years I duly fulfilled the hopes and dreams they'd harboured when hankering for a daughter: I was cheeky, vivacious and "utterly charming". If the photos are anything to go by, I wasn't particularly pretty, and certainly not thin. I was a solid toddler, as one might expect since I'd weighed 11½ pounds (5.2kg) at birth. Clearly my personality made up for the fact that my looks weren't as fine as they might have hoped for. All well and good – except when I started to get plump at around nine years old.

I have no memory of suddenly eating more or exercising less; there is no logical explanation for the increase in size. I wasn't enormous, but I was plumper than my peers and my siblings, and this began to concern my parents greatly. I recall once complaining to my father about the discomfort I experienced when the tops of my thighs rubbed together, causing sore, red patches, to which he replied, characteristically obliquely, "Try pushing yourself away from the table." At the time, as children tend to, I took him literally.

On one memorable evening it was made clear to me I needed to deal with my weight and, moreover, that my parents found it intolerable. The whole family sat down for a supper of mince and mashed potatoes. (In itself this was memorable, since we very rarely ate all together. In the 60s, when I grew up, adults always ate separately, differently and inevitably better than kids.) Before we began eating, Dad stood up, looking a bit uneasy, cleared his throat and announced, "Arabella won't be having potatoes because she's fat." I remember feeling overcome with rage and indignation – why should I be punished for something that was out of my control? I only ever ate what my siblings ate. It wasn't my fault if my body processed it differently. I wasn't doing this on purpose to annoy my parents. However, it would appear this was exactly what my parents thought was going on. My oldest brother, Andrew, protested on my behalf, drawing attention to his own (albeit very slight) plumpness. "That's different, you're a boy," my father said.

Our parents were highly educated, left-leaning and shared many social values, including our mother's distaste for housewifery – while Dad expected to enjoy a well-run home, he did not expect it to be at the cost of Mum's intellect or sense of fulfilment – yet neither of them saw any paradox in separating a boy's physical requirements from those of a girl. The message was loud and clear: girls need to be pretty, boys don't.

Needless to say, neither of them then went on to educate me in the ways of dieting or exercising more. In order not to annoy them and be more lovable, I simply needed to be less fat. Unsurprisingly, this method did not work. I soon learned never to express hunger around them and to eat in secret, thereby developing an inextricable emotional link between what I ate and my ability to be loved. From then on, if I eschewed pudding, potatoes and biscuits in their presence, they were pleased and congratulatory – they did love me more. If I ate anything "bad" in front of them, the reaction was guaranteed: a flamboyant roll of the eyes, heavy sighs or loud cries of, "Do you do this on purpose to annoy me?" or "Have you any idea just how fattening that is?" My mother's favourite line was, "Watching you eat is like having hot knives stuck into my eyes!" The link between worthiness and abstinence – or, in reality, thinness – was unmistakably demarcated.

This belief has never been more evident than it is today. Society prizes a girl for being thin more than anything else she might bring to the table. With this pressure in mind, and acutely aware of the trap into which my parents had fallen (I know they loved me, but they also never denied loving me more the less I weighed), when I had children, I made a decision to avoid investing food and eating with anything other than love and ease. And that's when I found out that feeding your children is a minefield – much harder than one might think before becoming a parent and, I reluctantly admit, even harder if you have a girl when you yourself are a girl with "eating issues".

I'm not letting my parents off the hook, but I now know that attempting to nurture a healthy and relaxed approach to eating is hard. My parents' generation's benchmark was simple: Fat Equals Bad. These days not only do we have that message shoved down our throats, we are also bombarded with horror stories of child obesity and the huge rise in popularity of sedentary children's activities (favoured because they'll be abducted if they're allowed to play out, so we're led to believe), plus the five-a-day fruit-and-veg diktat. (I literally break into a sweat if their bedtime approaches and I've failed to meet the target – many is the night I've tried to persuade them to eat a selection of crudités in bed.)

Little wonder it's harder than ever to foster a stress-free approach to eating. And this is particularly true for women, to whom the relentless task of providing family meals almost always falls. Women are told we need to be thin to "count", while at the same time being charged with ensuring our children eat well but not too much; that a chocolate biscuit or two is OK, but eating the whole packet is not; that being skeletal is neither healthy nor attractive. Simultaneously, we must also aim to develop in them, the next generation, an egalitarian attitude to size and gender. It's a tall order. We have to be on high alert all the time.

I've got a boy and a girl; their parents are a boy and girl (me). The boys eat more than the girls, yet aren't overweight. My 11-year-old son never thinks about what effect eating might have on his body – if he wants something, he eats it. So far, food has no emotional value for him at all. And that's just how it ought to be. My daughter, who is 12, thinks about fashion as much as most girls of her age. She eats well and healthily, the same food as her brother, but less of it. Their father and I have avoided saying anything negative when more ice-cream, chocolate, biscuits, cake, is inevitably demanded. "Everything in moderation" is the aim; nothing is off limits, just the amount. So far, so good.

But I don't know what I'd do if one of my kids began to gain weight. Naturally I'd look to myself first, and check what and how much I was providing; but what if the weight gain was the result of food they were eating outside the home, for example, chips with their mates on the way home from school? In an ideal world, I'd bite my tongue and ride this phase out, hoping it was just that – a phase. During which a loving parent, desperately trying as I am not to attach any emotional value to food, is required to stand by and let their child make their own mistakes. But I can't say that would be right, either. I wish my parents hadn't made me feel that how I looked was linked to how much they loved me. But I do also see how hard it must be to see your child pile on the pounds and trust they'll find their own way back to a healthy weight.

Being able to be around food and never wonder if there'll be enough for you, never to worry if you'll be judged for what and how much you're eating – to be able to expect and enjoy good food and to feel entitled to it – is a fantastic gift. But, like any gift worth having, in the first place someone has to give it to you.

• The Real Me Is Thin, by Arabella Weir, is published by Fourth Estate, priced £16.99. Order a copy online for £11.99 with free UK p&p, at the Guardian Book Shop.

He won't eat veg, he loves junk food and he won't exercise. So why is my husband in the least bit surprised that he's getting rather flabby?

'I'm fat," announces my husband.

"That's OK, Toryboy," I say. "Our relationship has never been built on raw physical attraction, but on a kind of sick, intellectual curiosity and an emotional masochism on both our parts that neither of us had hitherto suspected. Your expanding girth will hardly change that."

"But being overweight leads to heart disease, diabetes and untimely death," he says.

"That's OK, too," I say soothingly. "Haven't I always told you that the only good Tory is a dead Tory?"

"But you don't want me to be incapacitated before I go," he says. "Think how nursing me would cut into your Will & Grace repeats-watching time."

The man has a point. I pause Will & Grace to look at him properly. A paunch is definitely present.

"How does one lose weight?" he asks.

"Well, there are two ways," I say. "You can exercise more… "

"No."

"Or you can eat less."

"No."

After prolonged discussion, during which he is persuaded that I am not hiding some secret third way perhaps involving the weight being licked off by kittens, he eventually plumps (as it were) for dietary emendation.

His ignorance – his swirling, fathomless, pitch-black ignorance – of what this entails is only gradually revealed, however. "I'm just having a sandwich for lunch," he reveals proudly the next day. I am impressed – usually it's pasta with a Super Noodles starter – until I see that said "sandwich" is a giant pot of prawn cocktail mix emptied into a bap. I remonstrate.

"But it's brown bread," he says.

"That doesn't make a pint of pink mayonnaise a healthy snack."

"What about the fact that it's cold and not what I really want?"

"That is what should count in our favour on all diets," I say with a sigh. "But never, ever does."

The next day, he wants to eat a pork pie on the grounds that it's "just pork and a bit of pastry". He appears to be under the impression that the meat in his 79p purchase from the local chain bakery is as pure a piece of porcine goodness as was ever carved off an organic Gloucester Old Spot, rather than a dollop of mashed pig lips and fat mechanically recovered from the abattoir floor. And that the pastry is made from fruit.

Starvation sets in over the next few days because he won't eat vegetables. Doesn't like them, won't eat them.

I'm sorry, did I not mention I am married to an eight-year-old boy?

He cannot or will not grasp the difference between calorific value and ability to satiate. In vain do I draw diagrams and construct equations that seek to show how a carrot can be more filling than a cake at less calorific expense.

Eventually, I invent the Salad Deviation Scale.

"You accept – even though you won't eat it, because you 'don't like leaves' – that salad is good for you, yes?" I ask him.

If he doesn't say yes, I promise myself, I will stab him through his engorged and overstrained heart, and put us both out of our misery.

"I am convinced that this is, at least, the prevailing wisdom," he replies.

This is enough – just – to stay my hand.

"OK then," I say. "So, before you put anything on your plate or in your mouth, you must ask yourself the following question: 'How different is this from salad?' So, if it's fruit?"

"Not very different."

"And you may eat. Anything with fat dripping off or scattered in lumps throughout it?"

"Very different. And I must not eat it."

I don't know about him, but I, at least, am a shadow of my former self.

'To be happier you have to turn sad thoughts and feelings into happy ones. Right?'

The pastime of shooting fish in a barrel has been unfairly maligned – like falling off a log, it's a hobby with a high success rate, which instils a sense of confidence and self-esteem – so I make no apology for turning briefly to The Power, the new sequel to the absurdly bestselling self-help book The Secret. Rhonda Byrne's first book revealed the one "great secret" of wealth and happiness, previously closely guarded by Plato, Galileo, Einstein and a few others: "Whatever you dream of can be yours," she claimed, "when you use the Secret." In what is sure to strike readers as a radical change in direction, The Power reveals "the greatest power in the universe – the Power to have everything you want". One can, Byrne implies, use the Power in combination with the Secret, though she never specifies how. (Probably you need a special adapter.) "Everything in the universe is magnetic," she says, so by exuding good feelings, you're guaranteed to attract good fortune, "like a magnet". As the Italians say, the mother of idiots is always pregnant; The Power would make an excellent christening gift.

To be fair to Byrne – who declined to be interviewed, as she has done since becoming embroiled in various lawsuits with new age celebrities featured in the movie of The Secret – the new book makes concessions to changing economic times. Where The Secret argued that vigorously upbeat thinking would lead sports cars and luxury homes to manifest in your life, The Power recognises that happiness isn't solely a matter of materialism. (On this, it frequently quotes Jesus, identified each time as "Jesus, founder of Christianity". Thanks, Rhonda!) Beyond that, it's just an ultra-extreme version of a positive-thinking philosophy much attacked in recent years as hopelessly unrealistic, pseudoscientific, politically questionable and liable to trigger worse mood crashes when it fails to deliver as promised.

What struck me, though, was a more fundamental problem that The Power shares with many far more credible approaches to happiness. It's not the fixation on making your every thought burst with positivity. Rather, it's the notion that manipulating the content of thoughts and feelings is the path to a better life. That's a basic assumption of much psychology, even the down-to-earth, evidence-based kind. Indeed, it seems tautologically true: to be happier, you have to turn sad thoughts and feelings into happy ones. Right?

Maybe not. Take one recent study, which found that while Russians are more likely to brood over problems than Americans, that brooding is less likely to lead to depression; indeed, for Russians, brooding seems to protect against depression. The hypothesised explanation? Russians brood from a "self-distanced perspective", as if watching events, and their responses, from a distance. The content of their thoughts is negative, but it's their relationship to their thoughts that's different.

Meditation teaches a similar lesson, as does the still youthful field of "acceptance and commitment therapy", outlined in Russ Harris's excellent book The Happiness Trap. The point isn't to improve your thoughts and feelings, or stamp out negative ones, so much as to "unhook" from them; to stop being a puppet they jerk around. This isn't a Secret, nor really a Power. It's more of a Useful Insight. Somehow, I doubt that'll be the title of Byrne's third book.

oliver.burkeman@guardian.co.uk

twitter.com/oliverburkeman

Can I drink alcohol while taking antibiotics? Is there a link between drinking milk and prostate cancer?

Is it a myth that you shouldn't drink alcohol while taking antibiotics? I often do and haven't felt remotely nauseous. If this is the case, why do doctors tell us to refrain?
It isn't a rule for all antibiotics, only for those that react chemically with alcohol to produce unfortunate side effects. The two that matter most are metronidazole (Flagyl) and tinidazole (Fasigyn) that are prescribed for certain bowel infections, including the notorious C diff, caused by anaerobic bacteria (bacteria that thrive in the absence of oxygen). If you drink alcohol with either of them, you will convert it into acetaldehyde, a noxious chemical that causes nausea, vomiting, flushing, headache and palpitations. The only other interaction between an antimicrobial drug and alcohol is with cycloserine, an anti-tuberculosis drug – the two together increase the risk of convulsions. It seems that alcohol doesn't pose a problem with other antibiotics, provided you don't drink too much. Then forgetting the dose, vomiting it up, and your liver failing to process the drug may come into play.

I read that there is a link between prostate cancer and drinking milk – should I stop drinking it or drink less? I'm male and in my 40s, and my father has been successfully treated for prostate cancer.
Keep drinking the milk. But make sure you eat plenty of green and root vegetables as well. They contain phytoestrogens that have been claimed to be the cause of the low incidence of prostate cancer in the south-east Asia. The milk and red meat link with prostate cancer was reported in the US, where the regions in which people ate the most fats and dairy products had the highest level of prostate cancer. One suggestion was that high fat intake reduces our ability to absorb vitamin A, which is thought to prevent prostate cancer from developing. Hence the advice to eat plenty of vegetables (a good source of vitamin A) if you eat a lot of dairy products and red meat. However, I suspect that you don't drink as much milk as the American study subjects. Stopping drinking it is overdoing things. A varied diet, as always, is the healthy way to go.

• Got a medical query for Dr Tom Smith? Email doctordoctor@guardian.co.uk

Could Greece's latest attempt to ban smoking, this time on patriotic grounds, finally persuade Greeks to kick the habit?

One year and two months ago to this day, I walked into a bar in Athens where, in a haze of smoke and much to my surprise, I was allowed to break the law. A ban on smoking in public places, imposed by the then conservative government, had just come into force.

Bars and restaurants across Greece that had not elected to cater exclusively to patrons who puffed (a special opt-out clause of the then law) faced stiff fines. My little drinking spot was one of them.

But it mattered not. A gravelly voiced woman seated on an adjacent stool – several cigarette packs stacked before her – was quick to allay any fear that either I or my friend, an Australian only too aware of the stringency of anti-smoking laws in her native Melbourne, had as we pondered the possibility of lighting up. "Hey guys, in this country whatever is illegal is legal," she smiled. "Rules are made to be broken."

For the remainder of the night, a little nervous perhaps but equally buoyed by the naughtiness of it all, we sneakily puffed away. We weren't alone. In a nation where over 40% light up daily, millions of others were merrily flouting the law, in what would soon became a collective snub to the measure.

Last night, barely 12 hours after the socialist government attempted, again, to turn enclosed places throughout Greece into a no-smoke area – with a blanket ban unprecedented in scope and severity – I tested the law once more. This time, in the presence of a government minister at a reception held in another downtown drinking hole, several of us lit up. We sat in open window seats that abutted the street as we knowingly broke the law. Sanction came from neither staff nor any of the municipal police tasked with enforcing the ban (even if it has been announced that September will be a "flexible" month).

"It seems old habits die hard," said a colleague who has resided in Athens for close to 40 years. "The only way this is going to work is if Greeks feel it in their pockets, if the law is actually implemented and people are fined." In the new Greece, lead by the avidly health-conscious, non-smoking George Papandreou, that is exactly what authorities say they intend to do.

In south-east Europe, Greece stands alone as the only country where anti-smoking laws have repeatedly met with lack of success. This year, even Cyprus (home to the heaviest smokers in Europe after Greece) managed to pass legislation that has successfully prohibited smoking in nightclubs, cafes, pool halls, restaurants and betting shops.

With Athens in the midst of economic crisis, the US-born Papandreou took the unusual step on Wednesday of appealing to the patriotism of his compatriots in asking them to kick the habit. Quitting, he said, would not only revolutionise attitudes with the improvement of lifestyles and health but help the country's debt-stricken finances by curbing the effect of smoke-related diseases on its overstretched public health system. Conservative estimates suggest that the nation's addiction to nicotine costs the state over €2bn a year.

But in these difficult times, when Greeks are being asked to stomach a draconian austerity programme of tax hikes, salary and pension cuts, the anti-smoking drive is also seen as a demand too far. With bar owners and restaurateurs leading the backlash – in the midst of recession the ban will, they say, have an devastating effect on business – many Greeks have publicly complained that the campaign is tountamount to an infringement of civil liberties.

"I've been smoking for 12 years and I don't intend to change my habits," said Sia Apostopoulou, a private sector employee, summing up the mood. "In Greece, these kind of measures don't last for long."

Will this latest attempt work? I won't be testing the new law again, but it's my bet that many Greeks will fume for some time yet before they agree to stub out smoking under dictate.

My transport difficulties began straight after I was diagnosed with a tumour

People, it is alleged, are greatly fond of talking about their "cancer journey". My own experience has, so far, been more of an enforced "staycation". Problems with transport emerged straight after the diagnosis of a tumour in my left breast. As I set about getting into a cab home from the hospital – after an abortive attempt at walking – a man rushed up, insisting that he had hailed the cab first, yanked on the door, and leaped in. Bizarrely, it was Terry Christian, the superannuated youth-television presenter whom I'd always thought had been criticised surprisingly harshly. Until that moment.

Journeying matters did not improve. I cancelled a week in France in favour of a sentinel node biopsy, a week in Spain to make way for a mastectomy, then a few days in Scotland to have a post-operative seroma drained. Next will come six months of chemotherapy, followed by three months of radiotherapy. So near-future opportunities for travel seem limited also.

I understand that my "journey" is meant to be spiritual, not least because kind people keep calling up and asking: "How are your spirits?" I feel bound to inform them that, as far as I can imagine, my spirits have breast cancer too – but in an up-n-lite way.

It is always emphasised that it is of supreme importance for people with cancer to be "positive". This makes no difference to clinical outcomes at all, as studies have clearly shown. But it does wonders for the supply of relaxed people willing to hang out with you as you skip merrily to the hospital, or pluckily convalesce in a witty nightie.

Foreign secretary William Hague has revealed his wife has suffered 'multiple miscarriages'. Only when a woman suffers three do doctors refer her to a gynaecologist or specialist miscarriage clinic

Between one in four and one in five of all pregnancies ends in miscarriage. That means that somewhere between 200,000 and 250,000 conceptions every year end that way. They involve pain, frustration, distress and fear for the women involved and their partners.

A woman has about a one in five chance of having one miscarriage, a one in 25 chance of having a second, and roughly a one in 125 chance of losing a baby that way for a third time, according to Dr Justin Clark, a consultant obstetrician and gynaecologist at Birmingham Women's Hospital. William Hague revealed last night that his wife, Ffion, had had "multiple miscarriages", including one this summer.

Most miscarriages happen in the first 12 to 14 weeks of pregnancy. A woman's risk of having one goes down to about one in 100 during the second trimester of her pregnancy.

It is only when a woman suffers three that doctors intervene. When that happens, she will be referred to a gynaecologist or specialist miscarriage clinic for further investigation. Women then usually undergo blood tests to see if they have any underlying medical problems that may explain why the pregnancies are not progressing, including "sticky blood", or antiphospholipid syndrome in medical speak.

Age and body mass index (BMI) are two significant key risk factors for repeated miscarriage, Clark says: "Once a woman goes beyond 37 her fertility starts to reduce quite a lot and her egg quality isn't as good."

The higher a woman's BMI, the greater her risk of suffering either one or a repeated miscarriage. Having a chronic long-term condition, such as diabetes, is another risk factor.

"In general a woman who has one or more miscarriages will ultimately go on to have a successful pregnancy, even after repeated miscarriages," Clark says. "But there are some sad cases of women having as many as 15 miscarriages and never having a baby." Recurrent miscarriage responds better to treatment when the losses occur in the first trimester.

There are five main causes of women losing a baby in this way, according to the Miscarriage Association: genetic, hormonal, immunological, infection or anatomical.

About half are due to genetics, and many of those occur around the time when the egg and sperm meet to form the embryo.

Hormonal problems can include, for example, the embryo failing to burrow into the lining of the womb. Anatomical problems, meanwhile, include women with a very small or heart-shaped uterus.

Discworld's creator on his new novel, living with Alzheimer's – and why he should be allowed to decide when to end it all

When, not very long ago, Terry Pratchett's father was given a year to live, Pratchett père took it, on the whole, philosophically. Father and son had plenty of time to "have those conversations that you have with a dying parent", and to reminisce about his father's time in India during the war. At one point, said Pratchett, in last year's Dimbleby lecture, his father suddenly said, "'I can feel the sun of India on my face,' and his face did light up rather magically, brighter and happier than I had seen it at any time in the previous year. If there had been any justice or even narrative sensibility in the universe, he would have died there and then, shading his eyes from the sun of Karachi."

If the universe refused to display narrative sensibility, then Pratchett Jr would: that moment returns early in his new novel, I Shall Wear Midnight, in which a gruff, essentially kindly old man is vouchsafed a vision of youth and sunlight (though, instead of Karachi, the sunbeams glint off a leaping hare) and expires as he describes it. Even Pratchett knows this is a tad too neat, however, so, this being Discworld, his fantasy kingdom on a flat planet sailing through space on the backs of four elephants who in turn stand on a giant turtle, Death makes a lugubrious wisecrack about it: "WASN'T THAT APPROPRIATE?"

Pratchett, when he arrives at his idyllic local pub in Wiltshire, turns out to be full of this type of humour – deliberate, slightly coercive, very self-aware. He seems a man used to being listened to: his sentences unspool evenly, sometimes a shade irascibly, from beginning to end, often as anecdotes topped and tailed and full of random facts, gloried in for their own sake – annual expenditure on farmers' boots in the 19th century; the ubiquity then of shoe trees; did you know that in Victorian England, most of the women read and most of the men didn't?

Partly, though, this is because he's been writing all morning: I Shall Wear Midnight, a young adult novel, was launched in central London at midnight on Tuesday, but, as has been the way throughout a career that has so far produced 50 novels (38 of them set on Discworld) and generated more than 65m book sales – Pratchett is already 60,000 words into the next book.

And for the last two and a half years, ever since he was diagnosed with posterior cortical atrophy, a rare form of Alzheimer's, and lost the physical ability to write, he has dictated those words into voice-recognition software. At first, in fact, he talks to me about the machine as if I am a machine (which is not entirely unwarranted: there is a tape recorder sitting on the table between us). ". . . And the nice thing is, contrary to what you might initially expect, comma" – we both burst out laughing – "yes, sorry about this, full stop."

Pratchett has announced that his new book will be the last in his Tiffany Aching series (Aching is a young witch), and the novel, a bridge between childhood and the adult world, is full of worldly darkness – death, domestic abuse, old women's corpses being eaten by their pets, depression. "I'm a fantasy writer," he says. "Called a fantasy writer. But there's very little, apart from one or two basic concepts in I Shall Wear Midnight, which are in fact fantasy. You have sticks that fly, but they're practical broomsticks, with a bloody great strap that you can hold on to so you don't fall off. And you try not to use them too often."

Aching is, in effect, a young social worker, and much of her supposedly witchy wisdom comes simply from being near to people in the moments when others are not, or from making mistakes. At one point, in exasperation, she gets her familiars, the Nac Mac Feegles, to whizz around a depressed woman's very messy kitchen and clean it up – succeeding only in terrifying her.

"Tiffany's parents got it right," says Pratchett, sounding for all the world like a promoter of Cameron's Big Society: "mobilise the village to deal with [somebody like that]." Aching has First Sight and Second Thoughts (and occasionally third and fourth) – but they are, respectively, "seeing what's really there, rather than what you want to see," and "thinking about what you are thinking": self-awareness by other names.

Pratchett knows there are strict rules about making things so dark when you are writing for children – "a child's instinctive grasp of narrativium is that this has got to end well" – but he is also very clear that, while his witch can take away physical pain (she draws it out into a ball, then dumps it), she cannot, and will not, take loss, sadness, or grief.

"I've lost both parents in the last two years, so you pick up on that stuff," says Pratchett. "That's the most terrible thing about being an author – standing there at your mother's funeral, but you don't switch the author off. So your own innermost thoughts are grist for the mill. Who was it said – one of the famous lady novelists – 'unhappy is the family that contains an author'?"

He doesn't say it in so many words, but that must also be combined with grief for the loss of his ability to write longhand, or type with anything other than one finger at a time (although, weirdly, he is still perfectly able to sign his name — "the bit that knows how to sign my name is an entirely different bit of the brain"); the grief of knowing that while he may have years yet, most of his other mental faculties will go the same way. But probably not suddenly.

"Every day must be a tiny, incrementally . . . incremental . . . incremental . . . – he stumbled over a word; you must write that one down," Pratchett says with a dark, almost-laugh. (Having been a journalist himself, before becoming a PR in the nuclear industry and thence a novelist, he rarely passes up a chance to remind you that he knows how journalists work) ". . . incremental . . . change on the day before. So what is normal? Normal was yesterday. If you lose a leg, one day you're hopping around on one leg, so you know the difference.

"The last test I did was the first where I wasn't as good as the previous time. I actually forgot David Cameron. I just blanked on him" – this time the laugh contains, what – a kind of ironic approval? "What happens is, I call it the ball bearing. It's there, it just hasn't gone into the slot." He cannot begin to do tests that require him to scribble shapes, but asked to list names of animals, "I industriously say more than you can possibly imagine" – you can just see the pleasure of the earnest nerd in school – "and we go on for a little while until she smiles and says, 'Yes, we know, we know.'

"And then there was the time with dear Claudia with the Germanic accent – which is always good if someone's interrogating you – and she said, 'What would you do with a hammer? And I said, 'If I had a hammer, I'd hammer in the morning. I'd hammer in the evening, all over this land.' And by the end I was dancing around the room, with her laughing. The laugh will be on the other foot, eventually, and I'm aware of that. But it shows how different things can be: I can still handle the language well, I can play tricks with it and all the other stuff – but I have to think twice when I put my pants on in the morning."

How does it change his sense of self? "Well – no one's policing their own minds more than an author. You spend a lot of time in your own head analysing what you think about things, and a philosophy comes. I think – this is going to follow me for ages – I'm open to moments of joy: the other day, it was just a piece of rusty barbed wire in the hedge. Something had grown over it, and the whole pattern, the different shades of brown, the red – everything made a superb construction. And I was just happy that I'd seen it. But then I think – and it may just be because I'm 62 – it's also made me more . . . cynical? About government. And more sure, which is why I'm doing the Dignity in Dying."

For nearly as long as he has been public about his illness, Pratchett has been public about his wish to choose when he goes, and his puzzlement that British law does not see the sense of his position. "I feel embarrassed that people from this country have to go, cap in hand, to die in Switzerland. Apart from anything else, it makes it a rich man's – or a soon to be much poorer man's – possibility." And people have to go earlier than they intended. "Exactly."

He has a lot of time for the law in Oregon, where doctors can give a terminally ill patient a "potion to take when life gets too bad. I believe something like 40% or more of the patients die without taking it. Which means that every day they're thinking, 'Hmmmm – today's worth living.' And then one day they don't, and they die. That seems to me a very human thing, and a very good thing, because they can think, 'OK, that's sorted, I've got the potion, now I can get on and try and get the most out of life.'"

Ideally, Pratchett would like things to be even more official than that: there should be tribunals – here he leans forward, looking intently at me over his glasses – of mental health professionals, lawyers etc, all over the age of 45, who would question the patient and try to ascertain that no one was coercing them, and that the choice was not "a passing fixation".

But that's incredibly difficult; in illness you're often dealing with depression. "Yes. Yes, I know. I know," he says impatiently. Of course he knows. "Nothing I can say or devise, and nothing anybody else can say or devise, is going to be perfect. But anything is better than some poor half of a couple in some house, devising something with ropes and pulleys, saying, 'If he pulls this and we use that . . .' – that's obscene."

Currently, that half of the couple can, in theory, be prosecuted for murder. At least with a tribunal, "it would mean that whoever is left behind is at somewhat less risk – they're probably still at some risk, but at least there would be some proof that the situation was there."

Part of me wonders if the publicness of Pratchett's discussions might, on some level, be trying to achieve this too – getting us to act as an unwitting tribunal and witnesses, if or when the need arises. What does Lyn, his wife of more than 40 years, think of all this? "I think my wife takes the view that . . . Actually, I think in her heart of hearts she takes the view that a hand will come out of the sky with a big flask, saying, 'Just the stuff you were after.' I think she takes the view that, um . . . that she would look after me. And I have not said to her – I have absolutely not said to her – 'I want you to do this, or I want you to do that.'" What about his daughter (Rhianna, 33, a successful games scriptwriter and, as she describes herself on her website, "general narrative paramedic")? "My daughter thinks, 'If Dad wants it, that's OK.' I don't think she has any particular interest in seeing me lying there like a baby."

That was certainly the way he felt about his own father. It was even, it seems, something his father wanted. Had it been legal, Pratchett says, and "if he could have sat up in bed and said goodbye, I'd have pressed the button. I wouldn't have been able to see for crying, but I would have considered that a duty."

• I Shall Wear Midnight is published by Doubleday at £18.99. To order a copy for £14.99 with free UK p&p go to guardian.co.uk/bookshop or call 0330 333 6846.

• This article was amended on 2 and 6 September 2010. The original referred to Nac Nac Feegles and First Sight and Second Sight. These have been corrected.

Eight years ago James Hipwell received a kidney from his brother. Now he prepares to go into surgery again, this time alongside his wife Rachel

When I started this column in June, I was just coming to terms with the fact that I was in end stage renal failure for the second time in my life. I have to admit I had no idea that only three months later, my wife and I would be packing our bags for a stay at the Royal Free Hospital in Hampstead and major organ surgery for both of us would only be a few days away.

Things have been moving very quickly now that Rachel has been given the green light to be a donor. Dialysis has given me a very basic form of kidney function, and so now that my health has improved a little, the hospital is keen to perform the kidney transplant as soon as they can.

They plan to transplant one of Rachel's kidneys – her left one specifically – into me next week. We had our final briefing from Alison, the Royal Free's live donor transplant sister, yesterday.

From this Friday, she told me to start taking a huge dose of Tacrolimus, the main immune-suppressant drug and one of the most expensive ones permitted by NICE. The doctors want to use the "Tac" to batter my immune system to pieces with the aim of reducing the risk of my body rejecting Rachel's kidney as much as possible.

I will be going into hospital on Monday. They will dialyse me that afternoon and again on Tuesday to make sure my blood is in as good a shape as it can be for the op.

Rachel will be admitted on Tuesday. We will be allowed to have a last supper together on Tuesday night before this momentous act in both our lives happens on Wednesday morning. Alison's turn of phrase sounded ominous when she said "they would come" for her at around 8.30am to take her to theatre. I'm not sure why, but I thought of Nazi jackboots clattering up the stairs in the Warsaw Ghetto.

I will be allowed to see my wife one last time before she goes under the knife but I know that we will hardly be garrulous. Nervous as hell and cracking bad jokes in a pathetic bid to ease the tension, I would have thought.

What I won't be able to put into words in the coldness of that hospital ward is the unalloyed love I have for her. That she is making this huge sacrifice for me I find difficult to comprehend. I mean it really is beyond the call of duty, isn't it? It is an extraordinary act and I know that we will have a unique bond afterwards.

She is my hero. As is my brother, who went through the same thing for me eight years ago. I'm one hell of a lucky guy.

By the late morning Rachel's team should have removed the kidney that is destined to be transplanted into me. Meanwhile, I will have been wheeled into a neighbouring theatre on the third floor of the Free, anaesthetised and ready for surgery myself.

Rachel will be in the recovery ward by midday whereas I won't be back in my ward until early evening. When I had my first kidney transplant in 2002 I remember feeling completely back to normal, abdominal pain aside, within a few hours of the operation. All my various blood figures, which before the op had been either far too high or too low, returned to normal almost straight away.

If the same thing happens this time following a successful transplant it will be the nearest thing Rachel and I, atheists both, get to witnessing a miracle.

Thanks to everyone who has left a message of support. See you on the other side, as they say.

• If you would like to join the organ donor register, you can do so here: uktransplant.org.uk

They're fried in fat and smothered in salt, but still we eat a heart-stopping 6bn packets of them a year. So why do we have an unhealthy obsession with potato crisps?

• Food blog: what's your favourite crisp?

In an unremarkable suburb of Leicester called Beaumont Leys is a big factory – or actually two, side by side. But let's not split hairs already. The point is that it's big; a winding 10-minute march from reception round to the delivery bays.

These bays are where the raw material comes in, which is potatoes. The variety changes with the season, depending on whether they've come straight from the fields in summer, or from storage during winter. There are Hermes, Saturna and, right now, round, pink-cheeked Lady Rosetta.

Let's follow her, briefly. She is washed out of the truck – shedding any small stones or vestiges of earth she may be clinging to – and carried by stainless steel conveyor belt to a spinning drum, where she's peeled of her reddish skin.

She then passes across an inspection belt, where practised human eyes beneath faintly ridiculous but absolutely obligatory hygenic hair-nets hunt out hidden blemishes. Then, razor-sharp rotating blades slice her into 1.3mm slivers of starch and water.

Next, the excess starch is washed away (or the slivers will stick together), and the excess water dried off (it plays havoc with boiling oil), and hey, it's frying time: three brief but, one can only imagine, intense minutes in a 5,400-litre tank at 180C.

Out come the slices, all curling and golden and smelling (believe me) very good, whereupon a fiendishly smart automated scanning device gives them all the once-over once more, shedding those that look less than perfect. Next it is into the big drum for seasoning, which you're not allowed to see because it's top secret. Then weighing and bagging (more smart machines), and that's it: in less than 20 minutes, Lady Rosetta has become a packet of crisps.

This doesn't, though, give a true impression of the grandeur of the whole operation. This factory, belonging to Britain's largest crisp manufacturer, Walkers, is the biggest crisp factory in the world. It processes 800 tonnes of potatoes a day. It has six, 200m-long production lines, each of which turns out three tonnes of crisps an hour. That's maybe 120,000 small 25g packets. Per hour. Times six.

And this is only one of Walkers's seven UK crisp plants. Between them, they produce 10m packets a day, satisfying just under half this country's appetite for potato chips.

In short, we eat an awful lot of crisps. They are a national obsession. Practically everyone has a favourite flavour, or an unexpected craving, while even those who don't like them feel strongly – worrying, as chef Jamie Oliver has done very publicly, that this very British habit is doing untold damage to the health of the nation, particularly its children.

And when you consider we get through an estimated 6bn packets of crisps and 4.4bn bags of savoury snacks a year – around 150 packets a person – you do wonder what our love affair with crisps is doing to us. Looked at by tonnage, we consume more crisps, crackers and nuts than any other European country.

Unsurprisingly, though, the people at the Walkers factory wax positively lyrical. "There is," says James Stillman, head of research and development, "the physical experience. The crunch, the smell, the taste, how the salt dissolves on your tongue, how the flavours develop in your nose. Take our Sensations Thai Sweet Chilli: put one in your mouth and think. There's a five-second journey going on there, but you won't get it unless you really think."

It is, claims Stillman, nothing short of an emotional experience – "there's a great deal of anticipation in opening a packet of crisps" – and if so, it's an emotion that a great many of us share. Hardly anywhere else in the world, with the exception of America, do people consume fried potato slices in the manner, the variety and the quantity that we do, with well in excess of 100 varieties to choose from.

Elsewhere in Europe, the potato chip is a savoury something served with an aperitif (a complement, say, to the olive). In Britain, it's a food in its own right, or, as the Savoury Snacks Information Bureau puts it, "indisputably an integral part of the British culture".

In fact, muses food writer Matthew Fort, who confesses to a love affair with crisps dating back to the days of Smith's Salt 'n' Shake: "Crisps are our olives. The continentals once had plain olive oil. Now there's extra virgin, single estate, first cold pressed, extra virgin single varietal first cold pressed – you name it. We used to have plain ready salted; now there's any number of flavours, as well as traditionally cut, individually hand fried and the rest."

Hardly anywhere else is it possible to walk into a supermarket, corner shop, newsagent, petrol station or pub and expect to see arrayed before you a dozen or more brands, styles, varieties and flavours of crisps including (seriously) Balti Curry, Steak & Ale Pie, Chargrilled Chicken, Chilli con Carne, Jalapeno & Coriander, Taw Valley Cheddar & Caramelised Shallots, Spaghetti Bolognese, Aloo Masala, Xtra Spice Buffalo Wing, Argentinian Steak and BBQ Kangaroo.

But despite such esoteric offerings, Walkers's – and the UK's – top five has remained unchanged for years: in descending order, Cheese & Onion, Ready Salted, Salt & Vinegar, Prawn Cocktail and Chicken. "We're creatures of habit," says Stillman. "We like what we like, but we occasionally like to experiment. At any one time, Walkers will probably have 15 flavours in the market: the first five are generally the same, the other 10 will be changing pretty much constantly."

In continental Europe, by contrast, you're basically stuck with plain or, for some reason, paprika. We, though, are besotted: when Walkers ran its Do us a Flavour competition last year, in which the nation was invited to invent a new crisp flavour, it received 1.2m entries (the most memorable suggestion, Stillman says, was Ear Wax). This year, in parallel with the World Cup, the company ran its Flavour Cup, "a celebration of national cuisines from around the world". The popular winner was English Roast Beef & Yorkshire Pud, confirming that at heart, we see the crisp as something uniquely, quintessentially British.

Except, of course, it isn't. Or at least, it probably isn't. The crisp was allegedly born in Cary Moon's Lake Lodge (or Lake House) restaurant in Saratoga Springs, New York, on 24 August, 1853, when a former tracker called George Crum, son of a Native-American mother and an African-American father, got fed up with a customer (who may, or may not, have been rail magnate Cornelius Vanderbilt) sending back his fried potatoes because they were too thick for his liking.

The third (or, according to some accounts, fourth) time this happened, Crum, enraged, sliced the offending solanum tuberosum into wafer-thin slivers, deep-fried and over-salted the result, and sent the dish out again hoping the guy would choke on it. But Vanderbilt (if it was he) loved them – you can't go wrong, tastebud-wise, with starch, fat and salt – and Saratoga Chips became a staple of the restaurant's menu.

(I say "probably not British", incidentally, because a recipe for "fried potato shavings" was reportedly printed in America as early as 1832, in a book based on an even earlier collection of recipes from England. There again, when the first confirmed sighting of native British crisps was reported, in 1913, they were being made in London by a man called Carter, who had supposedly stumbled across them in France. So who knows?)

Anyway. In 1920, Smith's Potato Crisps Company Ltd was formed in Cricklewood, north London, with Mrs Smith peeling, slicing and frying the potatoes in the garage and Frank Smith packing them into greaseproof bags (later with a pinch of salt in a twist of blue paper inside) and selling them across London from his pony and trap. The firm was so successful it had moved to new premises and hired 12 full-time staff before its first year was out.

The company ran into trouble in the Depression, however, undergoing the humiliation of being rescued by its Australian subsidiary. But hard times proved the start of something big and beautiful for Mr Henry Walker, a successful pork butcher in Leicester. In the years immediately after the second world war he was facing bankruptcy, as rationing saw his shops in Cheapside and Oxford Street, London, cleared of meat before 10am, with nothing left to sell.

"It was a choice between ice-cream and crisps," former managing director Gerry Gerrard told the Leicester Mercury years later. He went for crisps because of the difficulties of handling meat and dairy products together. Walkers began in 1949 above the Oxford Street premises, with a staff of eight and Gerrard himself as head cook. The crisps were hand cut with a vegetable slicer, cooked in a chip-shop fryer, sprinkled with salt and sold for thruppence a packet under the slogan Potato Crisps by Walkers: Guaranteed Absolutely Pure.

They went down a bomb, and Walkers – which long ago swallowed Smith's, and is now part of the mammoth PepsiCo conglomerate – never looked back (helped in no small measure, since 1994, by the inspired choice of local lad Gary Lineker to front its advertising campaigns). We're no closer, though, to knowing why crisps are so big in Britain. What makes us, and so few others, so peculiarly partial to the potato chip?

There are plenty of theories. For Fort, it's mostly down to our unique relationship with the potato. "The potato has iconic status in this country; it's a subsistence food," he says. "A love of the potato is hard-wired into our gastronomic DNA. Plus, we've always been a grazing, snacking culture – look at our eating opportunities, we have more than anyone else: breakfast, elevenses, lunch, tea, high tea, supper, dinner . . . The French, the Italians, the Spaniards, eat twice a day, max. They're not snackers. The crisp is the perfect food for us."

Stillman reckons it has a lot to do with our high consumption of sandwiches, for which crisps are "an ideal complement", and of beer (ditto): "The creaminess of the potato, the salt and sweetness of the flavouring, the bitter of the beer; it all works." Felicity Lawrence, author of a brace of deeply scary books on the darker side of Big Food, also thinks pubs have something to do with it, but believes the underlying reason is that Britain industrialised earlier than most of the rest of Europe.

"Other countries maintained a more direct connection with their food and the land," she says. "We've been producing processed food for much longer, and consuming it too – there was a need for fast food from a very early stage, because people were working long hours in the factories." The crisp, then, is one of the earliest and most successful products of the long and happy marriage between industrialised food and a cheap, abundant crop.

Although the spectacularly competitive British market (remember Golden Wonder?) has been evolving and expanding pretty much since the crisp first arrived, aficionados point to two key revolutionary events: game-changing moments. The first was in the late 1950s, when years of kitchen experimentation by the late Joe "Spud" Murphy, proprietor of the cunningly named Tayto crisp company in Ireland, culminated in the invention of what is generally (though not, crisp history being a much-disputed field, universally) agreed to be the world's first crisp seasoning: Cheese & Onion.

The second major event was the arrival on these shores, in 1987, of an Oregon businessman called Cameron Earl, who brought with him a concept known as the Kettle Chip: thick, gnarled, irregular, crunchy, authentically flavoured and (naturally) more expensive. This was the premium product the hitherto classless world of the crisp had been waiting for, and it wasn't long before we saw an array of home-grown, artisan-inspired, hand-fried, organic rivals: Tyrrells, Burt's, Piper's and the rest. Walkers jumped in, too, with Sensations.

These are mostly known as "sharing" crisps, because they're sold in bigger bags, for more sociable consumption, and they're changing the shape of the market and the way we eat crisps. "They're for sitting on the sofa watching The X Factor," says Stillman, "not munching with your lunchtime sandwich." Sales of individual packets are falling slowly as sales of sharing packets, worth £370m last year, rise.

A posher product image, though, does not make for an inherently healthier product. Sharing crisps are almost all still cooked in fat and sprinkled – most of them – with salt (albeit Maldon sea salt) just as much as their down-to-earth cousins.

Four years ago, the British Heart Foundation famously warned that half of all British children were, in effect, drinking five litres of cooking oil a year by virtue of their packet-a-day habit (crisps are a staple in 69% of lunchboxes). More alarmingly, nearly a fifth of British children apparently eat two packets a day. Soaring rates of obesity and Type 2 diabetes were, the foundation warned, the consequences.

The crisp manufacturers complained of unfairness, inaccuracy and exaggeration, and the Savoury Snack Information Bureau – among other things, an active and effective rebuttal service founded to "ensure balanced reporting on the nutritional aspects of savoury snacks in the UK – swung into action. But the industry was stung, and has responded. "It's fair to say awareness has moved on," says Victoria Taylor, a senior dietician at the foundation.

"There have been reductions in salt content and sugar content and saturated fat intake, which is good, although crisps are still fried in fat, so calorie-wise that's not marvellous. There's no more advertising of junk food on children's television, although it's still on programmes lots of children watch. But we need to go further. It's all a question of balance. There are no individual foodstuffs I'd say you should never eat. But if you're eating something once or twice or more a day, then there's no room in your diet for the other foods you need."

In Leicester, they know the numbers off by heart: savoury snacks account for just 1% of saturated fat in the average UK diet, they say. Walkers has spent £20m in research and development since 2003 to make its crisps healthier. Most now contain up to 80% less saturated fat and 55% less salt than they did in 2006. New ranges such as Baked and SunBites contain between 30% and 70% less total fat, and 45% less saturated fat, than standard crisps.

"The point," says general manager Ian Ellington, "is that we have to make a product that consumers want. In the longer term, we're all moving towards consuming less fat and fewer calories, to making healthier choices. If we don't adapt and transform our portfolio, meet those needs while continuing to deliver taste and texture, then there won't be a Walkers brand."

Others are more sceptical. "It's just an idea of pleasure," says Lawrence. "Don't get me wrong, there's nothing wrong with enjoying a pack of crisps every now and again. But the truth is we shouldn't be eating them often; and that's the problem. Because they're selling so little, a packet of air and a few bits of something very cheap, the only way they can make money is by constantly reinventing themselves, and by making sure we eat an awful lot of them."

So, everyone. Are you more Cheese & Onion, or Taw Valley Cheddar & Caramelised Shallots? Personally, I can never decide.

• This article was amended on 1 September 2010. The original said the Britons consume more crisps, crackers and nuts than everyone else in Europe put together. This has been corrected. It also said that larger ("sharing") bags of crisps now account for 29% of the UK crisp market, against 25% five years ago. This has been deleted pending further checks on whether this holds true for the whole market, or specific companies only.

Harry Potter author funds Edinburgh university research centre named after her mother, who was killed by the disease

The author JK Rowling has donated £10m to set up a clinic to research treatments for multiple sclerosis, the degenerative disease that killed her mother at the age of 45, it was announced today.

The Anne Rowling regenerative neurology clinic, which will be based at the University of Edinburgh, will carry out research into a range of degenerative neurological conditions and diseases including Alzheimer's, Parkinson's, Huntingdon's and motor neurone disease.

The Harry Potter author has championed research into multiple sclerosis. In 2006, it emerged that she had given a "major" but undisclosed gift to Multiple Sclerosis Society Scotland towards setting up the university's centre for multiple sclerosis research.

She had served as the patron of the society, but resigned last year after an internal battle over the charity's reorganisation.

The university said the £10m was the largest direct donation Rowling had made to a charitable cause, and the biggest single gift the university had ever received.

"I have supported research into the cause and treatment of multiple sclerosis for many years now – but when I first saw the proposal for this clinic, I knew that I had found a project more exciting, more innovative, and, I believe, more likely to succeed in unravelling the mysteries of MS than any other I had read about or been asked to fund," the author said.

"I have just turned 45, the age at which my mother, Anne, died of complications related to her MS.

"I know that she would rather have had her name on this clinic than on any statue, flower garden or commemorative plaque, so this donation is on her behalf, too, and in gratitude for everything she gave me in her far too short life."

Unlike laboratory-based research centres, the new clinic will work with MS sufferers and help develop and test new treatments that could slow, stop and eventually reverse degenerative diseases. It will be based in a purpose-built unit within the BioQuarter medical research campus, in south-east Edinburgh.

Staff will work closely with other university and NHS research units specialising in regenerative and neurological diseases.

Rowling's £10m gift is being included in the university's campaign to raise £350m towards research, increasing scholarships and bursaries and conserving its historic buildings.

Prof Sir Timothy O'Shea, the university's principal, said: "This exceptionally generous donation will provide great help in the worldwide effort to improve treatments for multiple sclerosis.

"Work at the clinic will build on the already existing important research strengths in neuro-degenerative disorders at the university, which benefit very considerably from our close partnership with NHS Lothian."

Rowling, whose personal wealth was estimated at £519m earlier this year thanks to the bestselling Harry Potter novels and films, has a long track record of charitable donations. She has also given £1m to the Labour party.

She had previously set up another trust – the Volant Trust, commemorating her mother's maiden name – which has an annual budget of £5.1m to support women and young people at risk of social exclusion.