Body-conscious teenagers may believe cutting out breakfast will help them lose weight, but the opposite appears to be the case, US research suggests.
In a five year study of more than 2,000 youngsters, those who skipped breakfast were found to weigh about 5lbs (2.3kg) more than those who ate first thing.
This was despite the fact that the breakfast-eaters consumed more calories in the course of the day.
But the study in Pediatrics found they were likely to be much more active.
The University of Minnesota research adds weight to a growing body of evidence that those who eat breakfast - whether young or old - are leaner than those who do not.
"It may seem counter-intuitive," said Mark Pereira, who led the research. "But while they ate more calories, they did more to burn those off, and that may be because those who ate breakfast did not feel so lethargic.
Around 25% of the group studied regularly missed breakfast, and the problem was particularly pronounced among young women.
"The real problem is the profusion of messages about obesity - we need to make clear that eating regular meals is vital - and that a proper breakfast is very important. "
National Obesity Forum
"It's not just a girl problem, but it is certainly more of an issue among this group," said Mr Pereira.
"They skip breakfast because they worry about weight gain - and it's ironic that the ones who aren't worried and eat in the mornings are the ones who keep their weight down."
Tam Fry, chairman of the Child Growth Foundation at the National Obesity Forum, said the findings of the study showed just how important it was to relay a clear and consistent message to young people.
"The real problem is the profusion of messages about obesity. We need to make clear that eating regular meals is vital - and that a proper breakfast is very important.
"If you eat well first thing, you'll feel brighter, you'll have more get up and go - and that will mean you'll expend more energy."
Teenagers are not the only ones who may benefit from sitting down to a proper breakfast.
In a study of nearly 7,000 middle-aged people in Norfolk, a team from Cambridge University found that those who ate the most in the morning put on the least amount of weight.
THE STUDY: Breakfast Eating and Weight Change in a 5-Year Prospective Analysis of Adolescents: Project EAT (Eating Among Teens)
Maureen T. Timlin, Mark A. Pereira, Mary Story, and Dianne Neumark-Sztainer
Pediatrics 2008; 121: e638-e645.