Here's a question that's near and dear to my heart: how do you define anorexia? There's the DSM-IV criteria which states the individual has to be less than 85% of ideal body weight, and not be menstruating. There's also the loosely used popular criteria of self-starvation. All of which can be true. So how, then, is someone anorexic versus just being a little muddled about how much to eat?

Luckily for us, scientists have been trying to answer those questions. Part of the problem with diagnosing anorexia is that most sufferers deny the presence of a problem. In my case, I didn't really think I was losing too much weight, or if I was, then it wasn't problematic. This all makes a clinical interview with a sufferer rather convoluted to say the least.

Then there's the next question: less than 85% of ideal body weight. It's clear that there is no one "ideal body weight," even when you control for age and height. Think about it: there's over 6 billion people on this earth, and that everyone who is, say, 5'5" like me should weigh precisely 125 pounds is ludicrous! For the vast majority of human history, there haven't even been scales! Yet the species persists.

(Dieters, take note of the above...)

Lastly, there's the need for amenorrhea. This doesn't work with men (obviously, unless the said male also has a functioning uterus, by which send the lad my way so I can write it up in JAMA and get rich!), as well as with young girls and post-menopausal women. However, there are specific hormonal changes that accompany anorexia (such as a decrease in the T3 thyroid hormone) as a side effect of malnutrition. There are also general decreases in sex hormones. This has been shown in men put on a semi-starvation diet- they have a decrease in sex drive and become completely and utterly obsessed with food. Sound familiar? I could go into the chicken and egg debate here, but that's just too much for one post.

There have been clear indications of the genetic links to both anorexia and bulimia, meaning that there's something more than just social pressures going on. There are also numerous structural brain changes that occur in people with anorexia, no doubt related to the malnutrition caused by the disease.

What would I like to see? Standard scientific tests to determine the bio/neurochemical changes that are hallmarks of malnutrition. A 500 pound woman can starve to death. Maybe it will take longer than someone who weighs 150, but it will happen. And it is the effects of malnutrition that need to be reversed, not necessarily weight gain (as would be the case for the starving 500 pound woman). I have had wonky thyroid levels at a weight higher than my usual. Right now, when I am a little shy of my pre-AN weight, my thyroid levels are within normal limits. Why? I'm giving my body the nutrition it needs. Weight be damned. I would also like to see PET scans used for diagnosis, rather than just research. They're expensive, to be sure, but a good diagnosis is worth its weight in gold.

No diagnosis is that easy. Hopefully, more and more people with anorexia will be diagnosed and treated before the disease becomes severe, which could make blood and brain tests less precise. But until we know more accurately what happens to a person suffering from anorexia, it will be hard to create an adequate case definition.