Kellie is happy for us to use her first name and to call her middle-aged would be just fine, she says cheerfully, because that’s what she is. She is less forthcoming when you ask about her weight. She doesn’t weigh herself any more, she says, though she probably weighs a bit more than she’d like to. She’s healthy, which is great because three years ago, at 5ft 8in, her broad muscular frame was down to seven stone.

That’s thin, I say. What did you eat? “You don’t,” she replies. “You drink warm water and really cold water because that helps your metabolism. I pretty much lived on sunflower seeds because that was protein to keep me going at work. Maybe a slice of fat-free deli turkey. You do your best not to eat anything at all.”

What seemed to make Kellie unusual as an anorexic patient, and the reason she is talking about it, is that when she first became ill she was 43. Not 15 or 18 as you might expect, not a teenager worrying about boyfriends and exams and why she didn’t look like Lindsay Lohan, but a mature woman with a husband, two sons, a dog and a job in insurance. It is only since she was treated at the Park Nicollet Health Services Eating Disorders Institute (EDI) in Minneapolis that doctors have started to notice that Kellie is not unusual, because they are now seeing a significant number of anorexic patients who are over 40, some by a couple of decades.

“The increase in mature anorexic patients has been phenomenal,” says the EDI’s medical director, Dr Joel Jahraus. “Three or four years ago they made up 13 per cent of our patients. Now they’re up to 38 per cent but we haven’t recognised the phenomenon until the last year.” The EDI’s oldest patient was 68.

Eating disorder clinics elsewhere in America have also noted an increase in the number of mature anorexic patients, and in Britain there is anecdotal evidence that more mature patients are seeking treatment, skewing the notion that anorexia affects only young women, and the medical fact that the average age of onset is 15 to 16. The EDI is responding with a new $32 million eating disorders facility that will open in 2009, enabling its specialists to treat mature and young patients separately.

The question then is why significant numbers of mature women are seeking treatment for anorexia. Were they around before, unnoticed by doctors? Are they women who became ill as teenagers when anorexia was first widely discussed in the 1970s, and who have now reached middle age? The experience of Kellie, newly ill at the age of 43, suggests that these theories don’t work for all patients. Or do these women, like teenage girls, become obsessed with their body image because popular culture tells us that if we want to be attractive and popular and successful we must be thin? Today’s middle-aged women are, after all, the first of their generation to have been confronted by unnaturally thin role models throughout their adult life.

Jahraus points out that there isn’t much research to go on, but the existing body of knowledge about anorexia does enable him to come up with some informed speculation. The first point is simply that there is now greater awareness of eating disorders than ever before, both within the medical profession and among the general public. This means that anorexic women are more likely to be identified and, as stigma associated with anorexia declines, more will seek treatment.

“Shame and guilt is an inherent part of an individual’s eating disorder and to overcome that we’d have to see a major change in society’s way of looking at anorexia,” says Jahraus. “That is starting to happen — Spain has outlawed models who are under BMI (body mass index) 18 which impressed us here. But at the same time society continues to tell us that to be happy you have to have the perfect body. Baby boomers have grown up with the idea that you’ve got to look good, and the expectation of an attractive woman has evolved from thin to outright emaciation. People think, ‘I don’t like how I look. I want to lose weight because I’m not meeting society’s expectations’.

“We see two types of mature patients, those who have had an eating disorder for many years, and those who are coming for treatment for the first time. They say, ‘Gee, I wanted to be healthy so I got into an exercise regime’. Then they find themselves ratcheting down the types of food they eat so that only two or three things are safe. Compulsive exercise is a big part of this — striving to be thin and using exercise to get rid of calories.”

Or, as Dr Alex Yellowlees, medical director of Glasgow’s Priory Hospital, puts it succinctly: “Society’s idealisation of thinness is a crazy myth, a belief system society buys into. It is extremely unhealthy and affects women of all ages.”

If male doctors have a sound understanding of the mindset of anorexic women, perhaps it takes a woman to emote on the body image pressures that perpetually confront us. Susan Ringwood is chief executive of Beat (Beating Eating Disorders, formerly the Eating Disorders Association), Britain’s biggest eating disorders charity, and she too is aware that increasing numbers of mature women are seeking help for anorexia. Might the unnaturally thin middle-aged protagonists of Desperate Housewives have an unhelpful effect on middle-aged women, I ask. This is Ringwood’s response.

“It’s one of those awful backlash things. Until recently older women weren’t visible, they disappeared off the pages of magazines, they had no aspirational model held up to them. Now there are women like Sharon Stone and Madonna in their forties and women compare themselves to them and find themselves wanting. We do know that there are some people who are particularly vulnerable to feeling that because they are so driven to be perfect.

“Then, because older women are presented in unrealistic ways, they feel they’ve failed. Yes, it’s being shown that you can be beautiful in middle age but it’s an airbrushed and slightly odd look. What you get in response is an almost desperate attempt to hold on to youthful attributes, either through not eating or over-exercising.”

For any anorexic patient, and this includes older women, their illness is triggered by a genetic component and one or more socio-cultural components. The genetic component relates to personality type — anorexic patients are typically perfectionists, high achievers and have a strong need to control, combined with low self-esteem — but this is not sufficient to trigger anorexia on its own.

“With teenagers, the socio-cultural factor comes from problems with adolescence and peer pressure. They’re striving to look the best, to have the best boyfriend,” Jahraus says. “With older women we see a high divorce rate and women are out there trying to look good, trying to find a partner, and I think that has done something to influence these numbers of older anorexic women we are seeing.”

Of the mature women I spoke to who have been treated for anorexia, none wished to be identified, and some preferred not to be quoted. With some their sense of shame was palpable, and they were frightened that people who knew them might recognise them and then know that they were anorexic. It might seem logical that if you are tall and weigh six stone, your friends have probably worked this out, but it is common for chronic sufferers to become isolated not just from other people, but from their thought processes too.

The word they all used repeatedly was “control”. They felt that when they encountered problems, anorexia was a way of demonstrating a sense of control and gave them a sense that they were good at something. They recognised that society puts women under ridiculous pressure to be unhealthily thin, and this had contributed to the onset of their illness, but once it was entrenched their motivation to restict their eating came from their need to maintain control in the midst of a chaotic or failing life, rather than a desire to look like Teri Hatcher.

At the National Centre for Eating Disorders in Surrey, Deanne Jade, a psychologist, suggests that the American announcement of increased numbers of mature patients is “cute”. These patients were identified in 1979 as anorexia tardive (late onset), she points out, using the term coined by the late Peter Dally, a psychiatrist who pioneered effective drug-free treatment for anorexic patients. Certainly there are medical case histories of such patients on the internet, some in their seventies, but the onset of their anorexia seems to be related to loss, commonly divorce or bereavement. What we are seeing now seems to be more diverse.

Kellie believes that her anorexia was a response to feeling simultaneously under pressure as a working mother and as the child of sick parents. “I always believe that nothing will faze me, don’t let anything show,” she says. “But it’s got to come out somewhere. I had self-esteem issues — there’s such a huge focus on how you look. So you think, if I can look like Posh Spice my problems will go away.

“It’s about what you can control, and I couldn’t control all the things that were going on in my life, but I could control what I ate and maybe if I looked like Teri Hatcher or whoever I would be happy and people would like me.”

Kellie sought help when her sons started to stare at her and ask what was wrong. She is now well but still feels huge, she says, even though she isn’t. “It’s a battle. When something difficult happens I think right away, I’m not going to eat tomorrow. Then you think, how is that going to help? It’s so hard to break the habit of trying to deal with everything by not eating. My body image will probably never be OK again.”

Where to find help

Beat Helpline 0845 6341414: e-mail help@b-eat.co.uk: b-eat.co.uk

Anorexia & Bulimia Care 01462 423351: e-mail help@anorexiabulimiacare.co.uk: anorexiabulimiacare.co.uk

National Centre for Eating Disorders 0845 3673383