A quarter of young people admit they have ordered a takeaway to be delivered to their school, according to a survey by health campaigners.
They have called for a ban on fast food deliveries to schools, together with a range of initiatives to combat childhood obesity.
The Royal Society for Public Health, the Youth Health Movement and Slimming World magazine joined forces to carry out the survey of 13-18-year olds which found almost half blamed fast food takeaways for the epidemic.
More than half said they had ordered a takeaway through their smartphone while four in five thought food manufacturers were misleading people when they provide fat, salt and sugar for single servings rather than for the entire product.
The campaigners cite official figures showing nearly one in five 10-11 year olds are obese and call for initiatives including film-style classifications on unhealthy food and a loyalty card to reward healthy eating.
Shirley Cramer, chief executive of the RSPH, said: 'Young people are very clear what they think the causes of obesity are, and what action they would like to see from government and industry in particular.'