The Government may be wasting its time encouraging children to spend more time on sport and exercise in an effort to reduce obesity.

Research at Peninsula Medical School in Plymouth, reported in today’s times2, suggests that a child’s propensity to be active is genetically determined.

Children are said to find their own activity level, regardless of how many opportunities are offered. If the naturally inactive are forced to be more active at school, they do less at home, while the naturally active need no encouragement.

Professor Terence Wilkin, who has carried out trials with young people, says that his research shows that Government programmes to increase levels of activity do not reduce obesity. There are 1.8 million overweight children and 700,000 obese young people in Britain. Rates of obesity more generally have trebled since the 1980s, and the condition is estimated to cost the nation £7 billion in health expenditure.

But while active children may be healthier, it remains unproven that inactive ones can be persuaded to do more, Professor Wilkin says. “So far, the evidence is bleak,” he adds.

The claim follows US research last week suggesting that a fat gene can decide whether some people have a propsity to put on weight. Some research has suggested that activity does help. In one study, children who tried a nine-week programme with their parents, which involved a combination of exercise, healthy eating, motivation and positive thinking strategies, were still benefiting from the scheme 12 months later.

The researchers found improvements in the overweight children’s body mass index, waist circumference, fitness, lifestyle and self-esteem following the programme and these were “largely sustained” after a year. “Thirty per cent of UK children are now considered to be obese or overweight — it is an immense public health issue in both immediate and long-term health,” said Professor Alan Lucas, director of the Medical Research Council childhood nutrition research centre at University College London Institute of Child Health.

His “Mend” approach — “mind, exercise, nutrition, do it!” — was adopted by 107 families during the trial but it is now being rolled out across the country. More specifically, a study in Bristol found a link between increased activity alone and obesity, suggesting that an extra quarter of an hour vigorous exercise a day was enough to make a difference.

But the problem with these studies is that they do not show if fat children are fat because they are inactive, or inactive because they are fat. If Professor Wilkin is right, efforts to expand school sports may make children fitter, but no thinner.

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