Obese teens who lose weight at risk for eating disorders

Teens who were once overweight or obese have a significant risk of developing an eating disorder as they lose weight, says a new study published in the October issue of Pediatrics.

Based on an analysis of two case studies, researchers from the Mayo Clinic warn that identification and treatment of eating disorders in overweight teens is often delayed because medical professionals accidentally overlook them.

"Thirty-five percent of kids who are coming in with anorexia nervosa -- with restricted eating and significant weight loss -- started out in the 'obese' or 'overweight' weight range. And it takes them about a year longer to be identified," lead author Leslie Sim, tells Huffington Post.

Also see: Are 'fat letters' good or bad for kids and their families?

In both case studies, the teens had a history of obesity and developed severe, restrictive eating patterns in the process of losing weight.

"They come in with the same fear of fat, drive for thinness, and excessive exercise drive as kids who would typically have met an anorexia nervosa diagnosis," psychiatrist Jennifer Hagman from the Children's Hospital Colorado tells USA Today. "But because they are at or a even a little bit above their normal body weight, no one thinks about that."

And according to Sim, almost all eating disorders start with dieting, which can cause problems if they receive too much positive reinforcement for losing weight. Their dieting tactics get more severe, and soon the teens are skipping meals or going days without eating.

Also see: School obesity-prevention programs could actually trigger eating disorders

Lynn Grefe, president and CEO of the National Eating Disorders Association, says that overweight kids are more at risk due to being picked on.

"We know that if a child is obese, they may end up getting teased, picked on, discriminated against -- the list is long. They're vulnerable, by nature of that."

About 6 per cent of American youths suffer from eating disorders, according to a 2011 study in the Archives of General Psychiatry. And Canadian figures, while hard to nail down, are slightly lower.

Earlier this year, CTV reported that eating disorders in Canada were on the rise. According to the National Initiative for Eating Disorders (NIED), the rate of obesity is nine per cent in girls, while the rate of eating disorders sits at 18 per cent.