SCOTS teenagers are munching more fruit, salads and vegetables and taking more regular vigorous exercise, according to a detailed study of 5,600 young people.

There is still room for improvement, however. The study found that one in two 13-year-old girls is worried about being fat, and boys are also concerned about their weight.

Their concern is likely to be well-founded - around seven out of 10 admit consuming sweets, crisps and sugary, fizzy drinks every day.

Perennial teenage favourites such as chips, pies, hamburgers and sausages are still popular.

The findings were released by the Health Education Board for Scotland, which has analysed eating and exercise patterns of 11 to 15-year-olds over the past 10 years.

Martin Raymond, the board’s head of public affairs, said: “This is a study that begins to balance the picture. There’s some bad news but some very positive, surprising trends.”

Dr Candace Currie, an Edinburgh University researcher who carried out the study in 1990, 1994 and 1998, said health messages were beginning to reach young people who were taking action to look after themselves. Younger age groups significantly increased the amount of free time on physical activity. However, there is no social class breakdown of health and exercise patterns.

Only four out of 10 are physically active for six hours or more a week, but there has been a noticeable rise in the number of 11 to 13-year-olds exrcising.

Mary Allison, the board’s specialist on physical activity, said policies were starting to pay off. “Where things are provided and opportunities are available, young people take advantage of them.

“In terms of trends, there’s been a very positive shift for boys and girls over the past 10 years. The gap between boys and girls is one real concern and I would be concerned there are not enough relevant opportunities for girls.”

Different activities needed to be provided for girls who were sensitive about their body image, and hence reluctant to take part in traditional school sports.

Findings reveal significant rises among girls and boys in their consumption of fruit, raw vegetables and salads, matched by the proportion of 13 to 15-year-old girls eating cooked vegetables. More fish, pasta and rice are eaten every day but young people are drinking less milk.

Many more girls eat healthily, although diet fizzy drinks are popular among 13 to 15-year-olds. They tend to take far less exercise and almost half - 46.6 per cent - report being on a diet at some stage. Just under 16 per cent are currently on a diet and 47 per cent believe they are too fat.

Boys eat more of the wrong, high-fat foods and drink more full fat milk and fizzy drinks. But they are more likely to eat breakfast than are girls and to sit down for a meal with a parent. In contrast, they brush their teeth less often. Almost half the boys take regular exercise for at least six hours a week against 30 per cent of girls. Some 18 per cent say they have been on a diet at some stage.