About 10% of people with eating disorders (namely anorexia nervosa and bulimia nervosa) are male. Of these 10%, anywhere from 20-50% are homosexual. This is quite disturbing when you consider that only about 5% of the population is gay (with those numbers, you'd expect only about 5% of men with eating disorders to be gay).

I won't go into all the multi-faceted reasons which combine to put more than the average number of gay men at risk for eating disorders. But I do want to mention a couple of interesting points.

Contrary to what many straight people think, the gay community is not particularly accepting of its own kind (I can speak from experience as a gay man). Especially when it comes to physical appearances (which for some homosexual men are extremely—if not neurotically—important), gay men are relentlessly shoe-horned into a very limited number of categories.

Gay men, unfortunately, prefer one of two physical "types": well-built muscled men, or waif-like, adolescent-looking "twinks". (Part of the preference for well-built muscle men stems from social causes: many gay men try to bulk up to avoid the "AIDS look" of the 1980s; any signs of body weakness or wasting are seen as signs of illness and must be avoided at all costs. The preference for the thinner waifs stems more from biological and psychological causes: many gay men like delicate, effeminate, youthful-looking guys.) True, there are some fringe groups like leather men and "bears", but for the most part, gay men are carved up into one of the two former categories. There is no room for men who fall in between the two categories (which is, ironically, quite a large number of men—if not the majority*). In fact, if you lean towards the thin side but aren't "twink-like", you're considered fat. If you lean on the defined side but aren't as muscled as you can be, you're seen as lazy when it comes to hitting the gym and "taking care" of yourself (which to many gay men is usually restricted to physical regimes—and, of course, the nominal dose of pop-culture "spirituality" for good balance).

So basically, gay men who are "average" in physique find themselves having to alter their bodies to fit into one of the two major categories (not realising, of course, that the more they adapt to their respective categories, the more they perpetuate the categories). They either go out of their way to bulk up or they do whatever it takes to reduce their body weight.

For gay men who have pre-existing psychological issues, this unfortunate reality of the gay social scene puts them at increased risk of developing eating disorders (in general, eating disorders are determined by more than just the desire to look a particular way; otherwise, we'd all have eating disorders). Depending on the body type Mother Nature gave you, and if you're already at risk because of pre-existing psychological problems, various scenarios could play out, including the following vicious cycles:

1. In an effort to avoid any hint of the AIDS look, a gay man becomes an obsessive—and narcissistic—"gym bunny" and, if necessary, takes steroids and other "supplements" and maintains a strict, unhealthy, dietary regimen. The dietary regimen may include bulimic behavior aimed at maintaining a steady, normal weight and avoiding any weight gain  (it's important to note that bulimics, unlike anorexics, are able to maintain a normal body weight for their height and body type; so, just because a man doesn't look thin and starved doesn't mean he doesn't have an eating disorder). But because today's HIV+ positive men don't always look weak and emaciated (many look generally healthy, even after years of being infected), the slightest sign of physical imperfection in a healthy man must be avoided so as to ensure no question about one's health status (or one's commitment to "fitness"). As today's therapies increasingly delay the ravaging, physically deforming effects of HIV, a healthy, HIV- man can get caught up in a vicious cycle of conforming to an increasingly higher—and usually impossible—physical standard in order to differentiate himself from his ill counterparts.
2. A thin or average gay guy tries to bulk up and become a he-man, but it doesn't work and so he ends up punishing himself by starvation—becoming, in essence, the exact opposite of what he intended. This is not uncommon when you consider that most thin and average men cannot bulk up beyond a certain point; their bones are simply not big enough to support the amount of muscle they want to build.

*Note: While it may seem ironic that the majority of gay men, who are average in appearance, routinely discriminate against their own kind—the other gay men in the same majority of which they are a part—it's not necessarily an inexplicable phenomenon. In my own experience and observations, I've noticed that many gay men maintain impossibly high standards for physical attractiveness so they can have a ready-made excuse to avoid (for various reasons) long-term, monogamous relationships. If nearly every man you meet fails to meet your physical standards, then you have a convenient excuse for dumping him and moving on to the next one—something which is a perpetual activity for many gay men.