Being overweight and exercising regularly can be healthier than being slim and idle. So ditch the diet and get moving, says Tessa Thomas

In most people's minds the words "fat" and "fit" are worlds apart. However, as the focus on obesity and activity sharpens, it seems the two may be coming closer. "If fat people get fit, they accrue the health benefits of increased physical activity regardless of whether or not they lose body fat in the process," says Professor Chris Riddoch, who advised the Government on its physical activity report published last Thursday. "In fact, you can go further. There is evidence that fat people who achieve cardiovascular fitness through exercise have better health outcomes than lean people who don't."

Yes, we are a tubby nation - and yes, we need to reverse the uninterrupted 20-year increase in our mass. But, the latest thinking goes, this wrong-headed equation between being fat and being unfit will not help to change it.

"As long as people see physical activity primarily as a way of losing weight, they are unlikely to keep it up, either because it doesn't achieve that objective quickly or because they think they have to lose weight before they can take up serious exercise," Riddoch says. "The benefits can be achieved whatever a person's weight." And those benefits, across a range of 20 medical conditions, are often greater than those of the weight loss itself.

The notion that any activity involving the use of a tracksuit or leotard is only for the trim or toned is one that is peculiarly ingrained, says Joanna Hall, a patron of the activity campaigning body Move4Health. "The new guidelines challenge this assumption, because they explicitly relate to everyone, not just those with iron will-power or home-exercise equipment. The emphasis is on increasing everyday activity which anyone, including the overweight, can do to some degree."

Hall's experience as a fitness instructor backs up this inclusive approach. She has worked with obese clients with a body mass index (BMI) of 30 to 35 and has seen "significant improvement in their fitness, not to mention their self-esteem and dietary awareness". She is concerned that the many big people who put off undertaking exercise because of their size will only see their problem getting worse as they wait. "But, if they start, they'll see rapid and motivating improvements."

The Radio 1 presenter Amy Lamé (BMI 44 turned 36) would not call herself a self-starter. When approached by ITV's Celebrity Fit Club to participate in the series, she confidently declined. "I hadn't done any exercise since school sports, I'd never been on a diet in my life and was 20 stone - but felt OK." But after an incident on holiday when her bulk prevented her from lifting herself out of the water into a boat to get ashore, she decided she had no option but to enrol in the programme on return. "I only achieved what I did because it was a televised challenge with very specific goals and supervision. But the benefits of the exercise were incredible."

Apart from the small matter of losing three-and-a-half stone, the benefits included "feeling more energetic and mentally active and having the social side to it all. You don't get any of that from just dieting."

Hardly your typical gym bunny, Lamé - "still fat but less fat and a lot fitter" - now does aquarobics and makes regular use of the cross-trainer and treadmill at the gym. "There isn't much your size prevents you doing, apart from a few things that are tough on your already stressed joints, and I walk on the treadmill. The results for me seemed pretty rapid."

This is where the fat exerciser may have one over on the lean: because the extra weight they carry means that they use up more calories than a lighter person doing the same activity. If in the process they beef up their muscles, even while not visibly slimming down, the effect is compounded: each pound of fat carried on the body uses two calories a day, but muscle uses 20 calories a day.

Paul Campos, the author of The Obesity Myth (just published in the US by Gotham Books) believes that the health risks of being fat have been overplayed and the benefits of activity, for fat and thin alike, correspondingly underplayed. He says: "Many studies that apparently show the risks of being overweight or obese are actually looking at the risks of inactivity, because most fat people aren't active. But when you account for physical activity, being fat actually isn't the danger it's presented as."

Campos believes that the polarised view of obesity and fitness is beginning to shift. It's what you do with your body that determines health, to a much greater extent than what you put in it or what size or shape it is. Size and shape are often to largely genetically determined, he says.

To illustrate his beliefs, Campos draws on a range of studies, including oneby Stephen Blair and colleagues at the Cooper Institute in Dallas, Texas. Looking at 70,000 people over 20 years, they discovered that weight alone was a very poor predictor of mortality. But the people who engaged in at least moderate levels of activity were found to have half the death rate, regardless of their weight. Even if they were slim, the sedentary people died earlier. This research mirrors the findings of a British study carried out among 15,000 civil servants in the 1970s.

Mortality was the threat hanging over Kenneth Simmans when he decided to start exercising. "I'd retired early because of diabetes and asthma. I weighed 22 stone, never went anywhere without the car, and the GP said I'd better get exercising or else." Having hung up his car keys, he now walks everywhere, carries all his shopping, attends a weekly exercise class, has lost four stone and (although coy about his age) says he feels "20 years younger". He's now off his asthma and diabetes medication.

Simmans says that, although he is still officially obese, he finds the physical activity much easier at 18 stone (with a BMI of 36) "and it gets easier all the time, and I feel mentally more alert too". A BMI of 36 is high, but there is more to being fat than carrying excess adipose tissue. At his weight, Simmans is at high risk of "metabolic syndrome", the medical term for a group of disorders common among the obese that includes insulin resistance, adverse blood-fat levels, high blood pressure, glucose intolerance and increased blood clotting.

"Yet physical activity has a positive effect on all these factors, independent of body weight," says Dr David Ashton, lecturer in clinical epidemiology at the Imperial School of Medicine. Still, he cautions against seeing fitness as a guaranteed passport to longevity. "The studies quoted by Campos showed a strong correlation between fitness and low mortality, but this was at a population level. Fit individuals can still be unhealthy due to an underlying disease, regardless of weight, and of course it could be fatal." Still, fit fat people have a higher quality of life than sedentary ones. "Activity has just the same effects as on average-weight people: better sleep, more energy, less depression and a better ability to manage stress," Ashton says.

Although people like Simmans and Lamé appear to be fat-but-fit role models, there is a point - which both have experienced - at which excess fat coverage makes any exercise awkward, not to say risky. While it isn't too difficult to find routinely active people with BMIs of 25 to 30, above that level they are rare.

Campos claims that "the cut-off point for physical activity doesn't occur until someone has a BMI of around 40". That's a person of five feet nine tipping the scales at 19 stone. "But it's only a very small percentage of the population, which leaves a lot of self-styled fat people who are sedentary but could easily exercise."

But Ashton is dismissive of this view. "I see obstacles arising long before that, often around a BMI in the high twenties, when people start to lose mobility and find physical exertion problematic. By the upper thirties, the limitations are severe." Though these people can and should exercise, he says, they need careful advice on the type, intensity and duration of appropriate activity.He also cautions against over-emphasising the BMI figure, which does not discriminate between lean and fatty tissue.

Like other obesity experts, Ashton was critical of the regime of activities imposed on the hefty Celebrity Fit Club gang. "Some of them, such as the running, were totally inappropriate for overweight people and didn't take account of possible risk factors, such as a heart condition."

More appropriate for the wide of girth are those exercises enshrined in the new government recommendations: 30 to 45 minutes of moderate to vigorous physical activity on five days a week. "Moderate" is deemed to include activities such as vacuum cleaning, walking the children to school and back, DIY, mowing the lawn and cycling to work. "Vigorous" includes cycling, dancing and swimming. All can be done by the overweight, and many by the obese too.

But will these activities get people fit? Critics say they are insufficient for weight loss and, as most people are now overweight, something more ambitious is needed. But that is not the primary aim of the recommendations: as Riddoch says: "This report is about activity, not obesity, though in the public imagination the two things seem to get easily confused."



Exercise bike

* Works major lower muscle groups without stress on knees, back

* Strengthens the musculature in preparation for brisk walking or jogging

* Cardiovascular and respiratory benefits


* Uses all the major muscle groups if you swing your arms with each step

* Burns as many calories as jogging the same distance

* Distance is more important than speed

* Can be done any time and anywhere


* Cardiovascular fitness without stressing joints

* Involves all major muscle groups


* Strengthens core muscles, creating firm base for other exercise

* Restores strength to stomach muscles without sit-up stress

* Excellent activity for the very obese

* Easy to learn (you don't have to do regular classes)



* Stresses the abdominal wall and raises blood pressure (the abdominal wall may already be lax from the weight of fat)

Weight training

* Can elevate blood pressure

* Not recommended for weight loss

* Light weights can be used later