School children as young as 10 are going on diets and many pupils in the same age group consume large amounts of chocolate and soft drinks instead of healthier foods, according to a survey.

It found that 15 per cent of girls and 10 per cent of boys in fifth class were on a diet. One of the authors said a reason for this was young people wanted to achieve a "certain body type" promoted in the media and society.

The author, Des Broderick, senior lecturer at St Patrick's College, Dublin, said many 10year-old girls believed it was "sophisticated" to be on a diet. Others were forced to diet by parents who thought they were overweight. It was of "great concern" to have children so young on diets, he said.

The survey also found that while children were aware of what food and drinks were bad for them, about 60 per cent ate at least one chocolate bar a day and 58 per cent drank one soft drink a day. The survey of over 2,000 fifthclass pupils (typically aged 10) also found that watching television and playing computer games were the most common leisure activities after school, ahead of sport.

The survey by Broderick and Gerry Shiel found that 35 per cent of boys and 40 per cent of girls did not take part in sport outside school hours.

Broderick said the survey showed that many children led relatively sedentary lives. For example, it found that 34 per cent of pupils who travelled to school in their parent's car lived within a kilometre of the grounds.