• Mayo Clinic Minute: Breaking down types of eating disorders

As many as 1 in 20 American kids has what's known as a full threshold eating disorder. But more than half of American kids likely have disordered eating behaviors, and that can be just as harmful.

Dr. Jocelyn Lebow, a Mayo Clinic child psychologist who specializes in treating eating disorders, says eating disorders don't always look like people expect them to.

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"I see anorexia," Dr. Lebow says. "I see bulimia. And these are textbook – like made-for-TV-movie-style eating disorders. But I also see a lot of stuff in between. That doesn't mean [they are] less serious. It just means that their symptoms aren't classic – aren't exactly what you picture."

Dr. Lebow says there are many behaviors that classify as disordered eating. She sees patients take eating healthy to an extreme, such as never eating carbohydrates, fats or snacks of any kind.

Sometimes, she sees patients who exercise excessively, even when they have injuries. Many will regularly skip meals, while others hide food that they will only eat in private.

Even extreme pickiness is considered an eating disorder if a child only eats a small list of foods. For example, Dr. Lebow says a child might eat a hot dog bun, but refuse to eat a hot dog with it.

While these behaviors don't necessarily indicate an eating disorder, Dr. Lebow says if you notice unusual eating patterns, it's a good idea to get an assessment from a professional.

"I would say rule of thumb [is] if your kid is eating in a way that's not letting them be healthy – and by healthy ... what I mean is they're not eating enough to allow them to grow, to allow them to have energy to do what they need to do or, ... that it's impacting their mood – that's a problem," Dr. Lebow says.