Some obese teenagers who diet to lose weight are at risk of developing severe eating disorders including anorexia nervosa.
"They go on a diet and it starts out pretty benign and then they get some reinforcement and then they take a few more things out of their diet and then people say they look great," said Mayo Clinic researcher Leslie Sim, the lead author of a case study published in Monday's online edition of the journal Pediatrics.
"Then they decide, 'Well maybe I'll just skip some meals and maybe I'll go a day without eating," Sim said, adding that eating disorders in these kids may not be identified early because their weight loss is initially seen as positive.
On average, formerly obese teenagers are diagnosed with restrictive eating disorders 10 to 11 months later than their normal weight peers. Sim says well-meaning family members and physicians often contribute to a patient's eating disorder by encouraging diets rather than healthy eating.
"We can kind of understand why they're at risk," Sim said. "They're hearing it from all over that they're different, that there's something wrong with them, that they're unhealthy, that they're doing the wrong thing, they're making unhealthy choices, they're making the wrong choices and they need to do something about it."