The study, published today in the British Journal of Psychiatry, reveals a contrasting picture across the genders. Teenage boys are only unhappy about their bodies and becoming worried about their weight and shape if they are overweight and were unhappy with their bodies in childhood. Teenage girls develop body dissatisfaction regardless of their childhood weight.

The researchers, led by Dr Nadia Micali, looked at whether body image and weight in childhood could predict behaviours and thoughts consistent with eating disorders in adolescence. The team used data from over 6,000 participants in Children of the 90s (ALSPAC) when they were aged 14. The study is based at the University of Bristol. Using a scale to assess self-esteem, they found that higher scores at 8.5 years had a protective effect against developing body dissatisfaction and eating disorder behaviours as a teenager.

In particular, a one-point increase in the self-esteem scale at age 8.5 years decreased the odds of boys later engaging in self-induced vomiting or laxative use for weight loss at age 14 by 19%.

Researchers are recommending that public-health initiatives on body image might need to target younger children to prevent them from developing eating disorders in their teenage years. The study also highlights the need to have campaigns targeted by gender, due to the different risk factors for girls and boys.

Dr Micali, senior lecturer and honorary consultant psychiatrist at the UCL Institute for Child Health and associate professor of psychiatry at the Icahn Medical School at Mount Sinai, said:

The findings illustrate that we cannot wait around until young people reach adolescence to promote a healthy body image. Body dissatisfaction and weight problems are important risk factors that are present in childhood and might transition into dangerous disordered eating behaviours in adolescence, so interventions need to target younger children.

We also need to consider targeted prevention strategies based on the gender-specific risks rather than take a blanket approach. While it would be reasonable to target all girls who have high body dissatisfaction in late childhood, for boys it might make more sense to focus more on those who are actually overweight and have high levels of body dissatisfaction.

The evidence base for the efficacy of current eating-disorder public-health interventions is growing, but careful evaluation is required to ensure that the right risk factors are targeted at the right time.