In study conducted by King's College London, 261 teenage girls at three secondary schools were given a course of six lessons on body image.
With as many as one in three teenagers reported as saying they are dissatisfied with their body, researchers concluded that the lessons had significant effects on their body image and self-esteem compared with the regular curriculum.
Study lead Dr Helen Sharpe said: "We have tested whether a series of lessons being delivered by teachers to students in school are helpful in improving body esteem - we found this was the case.
"We're hopeful that as we continue with this research we'll be able to make the programme even more effective and that it could then go on to be effective in reducing disordered eating - things like binge eating and unhelpful weight loss."
Poor body image has been associated with depression, eating disorders, overuse of cosmetic surgery, obesity and unhealthy weight loss behaviours.
KCL's six-part programme focused on ideals of beauty, unhealthy interactions with peers - such as "fat talking", or making negative comments about weight - and practical measures for boosting mood and self-esteem.
The course was delivered by teachers in three state-funded girls' schools.
Interventions delivered by teachers would have wide reach and be of minimal cost, said the researchers.
Last year, MPs recommended that all schoolchildren should take part in compulsory body image and self-esteem lessons.
An inquiry by the All-Party Parliamentary Group on Body Image heard evidence that more than half of the public had a negative body image.
Girls as young as five now worried about how they looked, the MPs' report said, while cosmetic surgery rates had increased by nearly 20% since 2008.