You've heard the expression "calories in, calories out," right? Our bodies need a certain number of calories, provided by what we eat, to function normally.
If you burn more calories than you take in, you lose weight. If you burn WAY more calories than you take in - by severely limiting the types and quantity of the foods you eat, and/or by exercising for hours every day - then you exhibit energy deficiency.
Anorexia and bulimia are examples of energy deficiency based on lack of calories, nutrients, and other nutritional must-haves. The result of these kinds of conditions is not just weight loss, but painful thinness, one of the risk factors for osteoporosis.
Losing too much weight also causes a woman's body to lower its estrogen production. Less circulating estrogen (think menopause) is another osteoporosis risk factor.
Recently, a new food-based disorder has been making headlines: orthorexia nervosa, or just plain orthorexia. Characterized as an obsession with healthy eating, doctors are treating it as a compulsion, part of the obsessive-compulsive (OCD) spectrum of conditions, not unlike its two cousins, anorexia and bulimia.
So what's the difference between, say, anorexia, and orthorexia? Anorexia is the avoidance of eating. Orthorexia is the avoidance of foods the sufferer views as unhealthy - taken to the extreme.
People (usually women) with this form of OCD/eating disorder gradually condense their list of healthy ("allowed") foods till they might be eating only one or two things - say, raw carrots and brown rice. A woman who started out simply wanting to "eat healthy" by lowering fat, avoiding red meat, and increasing fruits and vegetables in her diet gradually finds fault with more and more of what she eats.
Especially if her healthy diet seems to be working - she's losing weight, feeling better - she might think, "Hmmm, maybe if I worked harder at this, I'd lose more weight and feel even better. What else can I cut out of my diet?"
The focus of orthorexia is removing unhealthy foods from the diet, rather than adding healthy foods. And, with all the media attention on food, there's a lot of misunderstanding and just plain misinformation out there: potatoes are bad for you. Red meat and sugar are both "poison." Cooking or freezing vegetables robs them of their nutrients. Eating celery is a "negative calorie experience."
If you're a person fixated on her diet in an emotionally unhealthy way, then you might just choose to believe everything you read. So you rid your diet of meat, potatoes, cooked vegetables, non-organic fruit, anything frozen or grilled, farm-raised fish, fish suspected to be high in mercury, GMO grains, corn syrup, transfats, processed foods, cured meats, "bad" carbs, non-local foods"
You can see where this is heading. At some point, by eliminating "unhealthy" foods from your diet, you've quit eating nearly all foods. And that, clearly, is much more unhealthy than avoiding "unhealthy" food.
Though orthorexia was first identified 13 years ago, there's still not enough data for doctors to have come up with any surefire treatments. Currently treatment focuses on the OCD element in orthorexia, at the same time gradually introducing a greater variety of foods into the patient's diet.
The vast majority of you reading this aren't experiencing orthorexia. But consider this a cautionary tale: too much of a "good thing" - even healthy eating - isn't healthy in the long run. And severe eating disorders are not only bad for your bones; they can threaten your life.
The best diet advice I ever heard came from Marion Nestle, a nationally known professor of nutrition at New York University: "Eat a little bit of everything."
Limit quantity - not variety - in your diet, and you should be just fine.