The study by the Schools Health Education Unit found that half of girls in grade eight, who were aged 12 and 13 wanted to be thinner, the 'Daily Mail' reported.
As many as 58 per cent of girls in grade ten, aged 14 or 15, said they wanted to lose weight.
During the research, 31,354 boys and girls aged ten to 15 were questioned about their eating habits and body image.
Young girls revealed how they were controlling their eating in their quest to be thinner.
A quarter of grade ten girls skipped breakfast on the morning they were questioned and 20 per cent had skipped lunch the day before.
Of those who had skipped breakfast, 36 per cent had avoided eating lunch on the previous day.
"An analysis of the characteristics of the year ten females shows that most of those wanting to lose weight are within the limits of healthy weight, and some are already underweight," researchers were quoted by the paper as saying.
The survey also found that while around 16 per cent of children thought that their health was down to luck, three-quarters of pupils in standards eight and ten said they felt 'in charge' of their health.
"One of the key features of current popular culture is a preoccupation with weight and shape and we know that poor body image and low self-esteem are key factors in the development of eating disorders," a spokesman for an eating disorder charity said.
