How far should we go in tackling the 'obesity epidemic'?

In the UK, obesity is fast becoming public health enemy number one. Almost one in four five-year-olds and one in three 11-year-olds is overweight or obese, according to a recent national survey. On current trends, 60 per cent of men, 50 per cent of women and 25 per cent of children could be obese by 2050. This century, obesity could supersede tobacco as the greatest cause of premature death in this country.

While few doubt that obesity is a health issue for individuals and society more generally, what can - or should - be done about it is less obvious. Is it a matter for individuals? Or the Government? Does the food industry have any responsibility? (See Big Picture on Obesity.)

Obesity is a deceptively complex issue. Its causes are simple enough - people consume more calories than they burn off. The obvious solution, then, is that people eat less and exercise more. Yet a strong genetic component to weight and a highly obesogenic environment make this solution far harder to achieve in practice than it sounds.

A report from the Nuffield Council on Bioethics in 2007 pointed out that it is actually very difficult not to put on weight in the current environment. The ready availability of food, much of it rich in calories and heavily marketed, together with reduced opportunities for physical exercise, has created an obesogenic environment.

As detailed in 'Big Picture on Obesity', the body has physiological systems to maintain body weight, with the hypothalamus playing a critical role in assessing the body's energy needs and regulating appetite and exercise. Yet the body's response to weight gain - rare before the 20th century - is much less powerful than its response to weight loss.

Attitudes

Attitudes to obesity are generally negative - a judge on 'Dragon's Den' has publicly said that he would not employ a fat person, while a survey of HR professionals in 2007 found that, all other things being equal in a two-horse race, 93 per cent would not employ a fat candidate.

And while exhortations to eat less and exercise more might be well intentioned, there is a risk that they send negative messages to those struggling to contain their weight. There is already evidence that the overweight are stigmatised and discriminated against. Constant messages that obesity is 'a bad thing' run the risk of reinforcing negative attitudes.

Many people would argue that our weight is wholly within our power to control - we just need to exercise some willpower. The evidence all around us, and from biology, suggests this is an unrealistic and unreasonable presumption.