While her family dines on flavorful Southern cuisine on holidays, Rebecca McCarter sticks to green veggies and plain chicken, though her grandmother’s fried cornbread used to be one of her favorites.

“I feel so left out of the family circle now when I can only pick around at the collards sitting on my plate,” says McCarter, a sophomore at the University of North Carolina Wilmington. “I eat things I don’t even like because I feel like I should only eat what my body needs.”

Dieting this way for about two years, McCarter’s 5-foot-2 body has dwindled to near 100 pounds. Yet she insists her strict food regimen isn’t driven by looks. “It’s not about feeling fat,” McCarter says. “It’s about my body not feeling healthy on the inside.”

From the Greek orthos, meaning “correct” or “right,” and orexis, meaning “appetite,” orthorexia is an extreme obsession with eating only healthy foods. What distinguishes orthorexia from eating disorders like anorexia and bulimia is the motivation behind the behavior. Like McCarter, someone who is orthorexic wants to feel healthy, pure and natural, whereas someone who is anorexic or bulimic wants to lose weight.

Juliet Zuercher, director of nutrition services at Remuda Ranch, an inpatient eating disorder treatment center in Arizona, says most orthorexics emphasize fruits and vegetables in their diets and often try to completely eliminate fat, sodium and carbohydrates.

Although an orthorexic’s fixation is on food’s quality rather than its quantity, Zuercher says diets that do away with entire categories of nutrients can have the same dangerous health consequences as anorexia and bulimia. “It is possible to have malnutrition even though you’re still eating a decent amount of food,” Zuercher says.

Colorado-based doctor Steven Bratman coined the term “orthorexia” in 1997 after his own bout with what he called “righteous eating.” Bratman later wrote the book Health Food Junkies on the disorder, and said that orthorexia begins as an innocent desire to be healthier but morphs into an almost spiritual way of thinking in which all of life’s meaning is transferred to food.

Bratman created a 10-step test to detect the disorder, however there has been little scientific research into orthorexia and a person cannot be clinically diagnosed with the disorder. The current edition of the Diagnostic and Statistical Manual of Mental Disorders, a handbook for mental health professionals, places eating disorders in three categories: anorexia nervosa, bulimia nervosa, and eating disorders not otherwise specified. Orthorexia falls in the latter of these categories, meaning doctors cannot give it as a clear-cut diagnosis.

Though they don’t have precise criteria with which to identify orthorexia, eating disorder specialists are familiar with the disorder and its potential dangers. Roberta Pearle Lamb, lead dietician at Walden Behavioral Care in Massachusetts, says she can spot when someone is hung-up on healthy eating because the diet begins to interfere with the person’s ability to participate in everyday life. The person becomes isolated from relationships and activities he or she once enjoyed, and thoughts of planning meals and feelings of guilt about eating take up a large part of the person’s day.

Lamb says orthorexia is likely becoming more common because of the movement toward organic foods and recent reports of food contamination. “It’s a healthy instinct to be more conscious of our food supply,” Lamb says. “But it has become trendy to be hyper-vigilant and make blanket statements about foods being completely good or completely bad.”

For this reason, Lamb says orthorexics often remain under the radar, their eating habits reinforced rather than questioned by the people around them.

Noah Eaton, a senior at Portland State University, developed orthorexia out of his distrust of government food regulations. “I thought about the ulterior motives the FDA, fast food corporations and major grocers have,” Eaton says. “I got all caught up in my fears and emotions.” On a severely restricted form of his already vegetarian diet, Eaton once lost 14 pounds within one month, and at his lowest weighed about 116 pounds.

Though Eaton is now trying to balance his diet, orthorexia has taken a toll on his muscles to the point that he can no longer do many physical activities, such as moving furniture or even playing Dance Dance Revolution.

Kathy Kater, a Minnesota-based psychotherapist who specializes in body image, eating and weight concerns, says people with all types of eating disorders have the same underlying anxieties motivating their preoccupation with food. “In any eating disordered person, there’s almost always perfectionism, a very rigid black or white, all or nothing approach to solutions, and a high need to be in control,” Kater says.

She adds that eating disorders are usually part of a dual diagnosis, meaning most people with an eating disorder also have another mental illness, usually anxiety disorder, obsessive-compulsive disorder or depression.

Because the underlying causes are similar, Juliet Zuercher says treatment for someone with orthorexia resembles treatment for other eating disorders, which involves meeting with a dietician as well as a therapist to find alternative ways of handling the anxiety driving the behavior.

“No one wants to walk around in fear, but we have to find another way for them to ease their fear, because food is never going to do it,” Zuercher says. “Food was never meant to meet emotional needs.”

For Rebecca McCarter, who is trying to overcome orthorexia without professional help, food is no longer an enjoyable part of family get-togethers like it once was. “I feel like I used to have a passion for food and wanted to try so many new things,” McCarter says. “Now I worry that I’m never going to be cured, and I wonder how I’m going to get through the rest of my life.”