Picture this: After spending the summer indulging in ice cream and cocktails, you decide to embrace healthy eating. You cut out refined sugar and packaged food-the kind of nutrient-free junk on any doctor's warning list. Wheat and dairy are the next to go.

People compliment you on your weight loss; your energy levels rival those of Jillian Michaels. But soon your innocent health kick takes a strange turn. Certain foods - even fruits and veggies - begin to seem dangerous, even unclean.

Within months, you've whittled your list of "acceptable" foods down to almost nothing.

This unhealthy fixation with eating healthfully is called "orthorexia nervosa," a term coined by Dr. Steven Bratman, a Colorado-based physician, in 1997. Since then, orthorexia rates have spiralled in tandem with society's insistence upon knowing every last detail about its food.

Orthorexia (derived from the Greek "ortho," which means "correct") often begins with a noble impulse - to get fit or eat organic - that grows into a self-destructive obsession where fewer and fewer foods meet the orthorexic's increasingly high standards.

The result is everything from malnutrition to social anxiety as orthorexics avoid restaurants and their friends' kitchens. At its most extreme, orthorexia can even act as a gateway to anorexia, says Merryl Bear, director of Toronto's National Eating Disorder Information Centre.

"The gateway possibility is very real because the principles are so similar," she explains. "Like anorexics, orthorexics prize being pure and in control above all else." (Orthorexia is currently classified as a form of disordered eating, not a clinical eating disorder, in the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association.)

Since orthorexics value purity, not weight loss, eating becomes a moral act. "A day filled with wheat grass juice, tofu and quinoa biscuits may come to feel as holy as one spent serving the destitute and homeless," writes Bratman in his book Health Food Junkies: Overcoming the Obsession With Healthful Eating (2004).

Bratman's theories about orthorexia - or "righteous eating" - eventually elicited such wrath that he stopped giving interviews and added a "Reader Hatemail!" section to his website. (Sample comment: "You are a moron. Please go to Mickey Dee's and chow down on a few Big Macs for us and don't call me in the morning.")

In a way, the controversy makes sense. As a society, controlling what we eat is now so normalized - understood as being "picky" or even "discerning" - that it is easier to miss the signs of risky, uber-controlled eating. "Food refusal has become a lot more socially acceptable," says Bear, pointing to the clamour of "can't eat" soliloquies that regularly greet servers and dinner hosts.

"People with serious food issues may get a pass because others don't fully understand what's behind their particular standards."

For orthorexics, the need to obsessively control their diet is exacerbated by the sheer amount of food knowledge available just a click away. Googling "healthy eating" yields almost 32 million results, including the 100-Mile Diet, the Dukan Diet and hundreds of websites devoted to breaking down multi-hyphenated ingredients.

Find out why society is in part to blame for this new generation of eating disorders on the next page...