Until recently, this disorder was known as "exercising too much", but there's more behind it. Exercise bulimia is where a person eats and then feels the compelling urge to exercise vigorously to burn off all the calories they just ingested. That determination can lead to dangerous health and social problems in the person's life. And I say "person's" because this subset of bulimia probably includes more men into the bulimia family.
I think we get too hung up on the motives for harmful activities. We build these definitions of disorders and then try to tackle deep rooted mental problems. Instead, why don't we just focus on the basics? Exercising too much is bad. Doing anything too much is bad. That's why it's called "too much". Because at one point it was enough, but then more came along and ruined everything.
With old bulimia, the problem is barfing up your food. Not a good idea, unless you've just eaten poison. Thing is, most would agree, throwing up your food to avoid getting fat is more severe than exercising to not get fat. So the purging bulimia is an issue, but exercising? Just set your limits. You can't really set limits on how much of your food you want to vomit up after dinner (even a little would be bad), but you can set limits on exercise. It's also easier to get people to stop exercising than vomiting, from my experience. Just take away their gym membership. Then they'll be forced to run around like a loon to burn calories and hopefully then, they'll realize the error in their ways. I don't mean to be belittle the exercise bulimia here, I'm just trying to help!