According to Dr Martin Bax, a paediatrician and senior research fellow at Chelsea and Westminster Hospital, London, growing numbers of 11- and 12-year-olds are entering secondary school with a weight problem, often going back several years. One or two children in every class are seriously overweight. 'A few children are so overweight, they're huffing and puffing as they climb stairs, and are as much as 50 per cent heavier than they should be,' he says. 'Obesity is potentially as life-threatening as anorexia.'
Like anorexia, he adds, obesity usually reflects a range of social and emotional problems. He has helped devise a school-based intervention programme for the children whose problem is too much weight, rather than too little; he works with a school nurse, Agnes Egan, in comprehensive schools in central and south London.
Both are keenly aware that fat children suffer from poor self-image and downright misery. 'Young people gain so much confidence if they feel better about about their bodies. Being overweight affects their whole life,' Ms Egan says. She and Dr Bax have learnt the usual approach to weight problems - a diet sheet together with a quick talk about healthy eating - simply does not help. According to Dr Bax, diet sheets rarely tell young people anything new. 'Many already have a detailed knowledge of calorie values, and know which foods to avoid if they want to lose weight. The point is they can't act on the information.'
Ms Egan says: 'Dieting alone is looking at it from the wrong angle. The causes of overeating have to be addressed before anything can be done.' Unsurprisingly, it is not the health risks of being overweight that worry the children most, but the way it affects their lives and the way they are treated by others.
Ms Egan says almost all overweight children hate being fat. 'More than 90 per cent say they feel 'sad' about it. It's a cause of bullying and teasing, as well as of avoiding physical education and school games.'
She believes obesity is nearly always the result of unhappiness. Many children - like adults - eat for comfort, often because of self-dislike, difficulties with school work or friendlessness. This loneliness is then made worse when a child is shunned and bullied simply for being fat. A poor relationship with parents, or sadness at a family break-up, can also lead to comfort eating.
The programme they offer to overweight children has developed out of the routine health check Ms Egan gives to all children when they start secondary school. It is during this first assessment that she picks up the ones with a weight problem. 'The children know I'm going to mention it, and they're anxious. But I bring it up very gently, and make them another appointment where we can discuss it properly.'
She gets the children to fill in a questionnaire to find out what their circumstances are, and to act as a starting point for discussion. 'Some situations, such as severe poverty, we can't do much about. But lots of children can be helped, and once they start to see they're losing weight their motivation can be very high.
The help is sympathetic and non-judgemental, and is basically a 'talking therapy' aimed at changing children's views of themselves and reducing their dislike of their body, so they can face problems in life without feeling the need to overeat. In many cases, the problems of being lonely and isolated disappear as weight is reduced and confidence increases.
The children can see Ms Egan whenever they like, although it is usually about once every two months. The sessions, which last up to half an hour, cover anything that is relevant to a child's perception of him or herself, including family problems, and concentrate on boosting morale rather than on diet and food. The programme will continue for as long as a child wants and for as long as it takes for the weight to shift. A minority with severe psychological problems are referred to Dr Bax.
Ms Egan's skill lies in knowing how to raise a child's self-esteem and in offering a sympathetic and supportive atmosphere for discussion. Often the help she offers is practical. The emphasis is on changes in outlook rather than changes in eating. 'We talk about what sort of clothes to wear. Some of them wear such dreary, drab things because they say nothing else fits. We talk about getting clothes that look trendy, even on someone who's bigger than the rest. Sometimes we decide a change of hairstyle would be a good move. Recently, I encouraged a teenage girl to get a Saturday job. That's really helped her. No one at the shop where she works has mentioned her weight, and she's gained a great deal of confidence.'
Being a school nurse is an advantage, she adds, because it means she can deal with the children directly rather than through the family. 'I may contact the parents in some cases if the children say they need the support of their family. Once, I wrote an explanatory letter to a boy's grandmother. She'd been undermining all his attempts to lose weight by telling him he needed more nourishment.'
In the US, birthplace of the TV-dinner, the couch potato and round-the-clock snacking, 'Fat Camps' are enjoying commercial success. For about pounds 2,000, a parent can send a child to a summer camp where a combination of a 1,400 calories-a-day diet, vigorous exercise and psycho-social support can lead to weight losses of 25lb to 50lb. Dr Bax is sceptical about this quick-fix approach. 'What happens when the children go back home, back into the same environment and perhaps back to the same problems that caused their overeating?' he asks.
His school-based programme is probably more realistic: it can take two to three years for the low-key, individualised approach to have an effect. The programme, he says, is less likely to work with children who are extremely overweight and have a history of overeating, as well as complex social and academic problems.
Even so, he feels that school is an ideal place to tackle weight problems. 'We'd like to see the management of overeating form part of the training of everyone working in the school health service - and the sooner the better.'