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. 

Eat the right foods to keep your bones strong.

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 is Adult Selective Eating? Like kids, adult picky eaters limit themselves to an extremely narrow range of foods. Unlike those who suffer from anorexia nervosa or bulimia, adult picky eaters are seemingly not worried about calorie counts or body image. But so far, researchers don’t know if adult picky eaters just haven’t outgrown childhood patterns or if their eating habits are a new twist on obsessive compulsive disorder. Some may be “supertasters,” with an abnormally acute sense of taste that turns them off certain foods. Many appear to have had unpleasant childhood associations with food.

• What is orthorexia? Identified in 1997 by Colorado physician Steven Bratman, MD, orthorexia is Latin for “correct eating.” Here, too, the focus isn’t on losing weight. Instead, sufferers increasingly restrict their diets to foods they consider pure, natural and healthful. Some researchers say that orthorexia may combine a touch of obsessive compulsive disorder with anxiety and warn that severely limited “healthy” diets may be a stepping stone to anorexia nervosa, the most severe – and potentially life-threatening – eating disorder.

What do they eat?

• Adult picky eaters: Food preferences tend to be bland, white or pale colored – plain pasta or cheese pizza are said to be common foods along with French fries and chicken fingers. Some picky eaters stick to foods with a common texture or taste.

• Orthorexics: Those affected may start by eliminating processed foods, anything with artificial colorings or flavorings as well as foods that have come into contact with pesticides. Beyond that, orthorexics may also shun caffeine, alcohol, sugar, salt, wheat and dairy foods. Some limit themselves to raw foods.

Check out this mobile phone app that guides healthy food choices.

What are the risks?

• Health consequences: Limiting your diet to only a few foods – because you’re a picky eater or have a long list of foods you deem unhealthy – can lead to potentially dangerous nutritional deficiencies. At its most extreme, a diet limited to only a few foods perceived to be healthy is described as orthorexia nervosaand can lead to the same emaciation and health risks seen with anorexia nervosa.

• Social Isolation: Being an adult picky eater can take an enormous social toll. Out of embarrassment, these folks avoid dining with friends or co-workers. Heather Hill tries to hide her eating habits from her children for fear that they will pick them up. Going to extremes in an effort to eat only healthy foods can also be socially isolating and can undermine personal relationships.

How are these disorders treated?

• Adult Selective Eating: Techniques that have proven successful in treating kids who are picky eaters – learning assertiveness skills and systematically trying new foods – are being used on adults, but it’s still too soon to know whether they work.

• Orthorexia: Cognitive behavior therapy designed to change obsessive thought patterns regarding food is usually recommended