In recent years, I've noticed a tentative move toward having Binge Eating Disorder included in the term "eating disorder."
Part of the reluctance of the ED world to do this is, I'm quite sure, based on prejudices about weight - putting people terrified of weight gain in the same category as people whose illness sometimes creates weight gain. Part of this is that BED hasn't been included in diagnostic ED categories until more recently - and not completely. Then there is the fact that most people still think of eating disorders as "not really about food," and there being some virtue and self-control being attached to eating and digesting less than one needs (untrue). I think it is also very common to confuse BED with "obesity" and the reverse.
The reasons BED is being incorporated more often now? I think people are realizing that all of these behaviors are rooted in the brain, and all involve restrictive eating (sometimes leading to bingeing, sometimes leading to purging and sometimes not). Another reason is practical and tactical: the "obesity epidemic" mania is bringing funding and attention to the ED world in a way that anorexia and bulimia just couldn't draw.
I will confess to being slow to incorporate BED into my own use of the phrase "eating disorders." I think I've been so eager to get people to pay attention to anorexia and bulimia - ANY attention - that I didn't want to complicate the message with all the ideological baggage out there about fat.