Hormone surges can make them moody, trigger sugar cravings and cause skin breakouts.

London - Schoolgirls as young as 12 are unhappy with their weight and some are skipping meals in an effort to be skinnier, a study has found.

Half of girls aged 12 to 13 – or in year 8 at school – said they wanted to be thinner.

And 58 percent of girls aged 14 or 15 (in year 10) said they wanted to lose weight, according to the study by the Schools Health Education Unit.

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 are controlling their eating in their quest to be thinner.

A quarter of year ten girls skipped breakfast on the morning they were questioned and 20 percent had skipped lunch the day before.

Of those who had skipped breakfast, 36 percent had avoided eating lunch on the previous day.

But if many of the girls keen to lose weight started dieting they could be putting their health at risk. The researchers said: “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.”

The survey also found that while around 16 percent of children thought that their health was down to luck, three-quarters of pupils in years 8 and 10 said they felt “in charge” of their health. Campaigners said the results were unsurprising considering young people’s exposure to airbrushed images of celebrities in magazines.

A spokesman for eating disorder charity Beat said: “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.

“The fascination with celebrities, their bodies, clothes and appearance has all increased the pressure that young people feel as they seek to establish their own identities – and typically at a time when their own bodies are growing and changing.

“Celebrities are scrutinised for flaws and imperfections, leading young people to consider their own bodies in a critical light too. Into this mix is added airbrushing and digital manipulation of images, creating a hyper-real perfection. Young people compare themselves unfavourably to these images and some are more affected than others, usually because they are more vulnerable.”

The same survey found that many teenagers feel they are not getting enough sleep to concentrate at school.

Twenty-eight percent of girls and 22 percent of boys in year ten thought they needed more sleep.

Overall, 80 percent of boys and 78 percent of girls in year eight said they got the recommended eight hours or more of sleep a night, but this fell to 65 percent for year ten boys and girls. - Daily Mail