This article is originally posted by Lisa Collier Cool.

I have a friend who will only eat short pasta, like penne. Another friend sticks to long pasta - linguini, spaghetti. I thought that was a bit bizarre until I read about Heather Hill, 39, whose diet consists entirely of French fries, pasta with butter or marinara sauce, vegetarian pizza, cooked broccoli, corn on the cob, and cakes and cookies without nuts.

Ms. Hill isn’t alone. New findings indicate that there may be hundreds, if not thousands, of adult picky eaters. To get a handle on the numbers, Duke University and the University of Pittsburgh have launched a national public registry of adult picky eaters. Respected publications like JAMA and Psychology Today are recognizing another new eating disorder, orthorexia, an obsession with healthy eating. That may not sound bad, as obsessions go, but those who carry good intentions too far can face serious risks.

Kristie Rutzel, 27, dropped to 68 pounds when she was in the grip of her fixation on healthy eating - at one point she ate little more than raw broccoli and cauliflower. Neither adult picky eating disorder nor orthorexia is included in the Diagnostic and Statistical Manual (DSM), the American Psychiatric Association’s “bible” of mental disorders. Once a disorder is listed, treatment is often covered by insurance and it’s easier for researchers to get grants to study it. Here’s what we know so far:

What do they eat?

What are the risks?

How are these disorders treated?