More than half of 14 and 15-year-old schoolgirls want to lose weight, figures suggest.
A study by the Schools Health Education Unit found that 58% of female pupils in Year 10 would like to shed some weight.
A quarter of Year 10 girls had no breakfast on the morning they were questioned and 20% had skipped lunch the day before.
Researchers said that of the girls who missed breakfast, 36% reported having nothing for lunch the previous day.
They wrote: "An analysis of the characteristics of the Year 10 females shows that most of those wanting to lose weight are within the limits of 'healthy' weight, and some are already underweight."
The questionnaire, conducted on 31,354 children between 10 and 15 years old across the UK, also found half of 12 to 13-year-old girls in Year 8 would like to lose weight.
Charity Beat said the figures are not surprising in a culture where celebrities are scrutinised for every flaw.
Young people also compare themselves to the "hyper-real perfection" of airbrushed images, a spokeswoman said.
She 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.
"Social and cultural pressures are strong in this area. 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 as they naturally mature and become adult."