Which, it should be pointed out, is true of all diets which are no longer being followed. No diet works when you just think about it.
Name a single diet where this DOESN'T happen. I know, you say eat healthy, & exercise, and you're absolutely right. But, whatever the diet, most people gain the weight back -- and more. Here's my biased opinion, at least for people who have had a weight problem ALL their lives. We have been told all our lives that it is psychological, we eat for comfort, etc. I bought that line of baloney (pardon the semi-pun) for many years. I no longer do. Something is biologically out-of-whack. And as you or someone suggested, there are things, drugs or supplements, that can help because otherwise the constant cravings for food (usually sweets and carbohydrates) will drive you insane. In my case (and ok everybody, flame away!!!!!!!!) what has worked is the evil prozac!!!!!!!
On it, I can actually think normally and not be obsessed with food 9/10's of the day. I also eat healthy, cut way back on carbs & sweets, and exercise. As one diabetic here said, there is very solid science behind the recommendation to cut out a lot of carbs (not necessarily as strict as Atkins, for example, there is one called "Sugar Busters.") Anyway, there are, of course, solid biological reasons why prozac works for some people, its serotonergic effects, so if there is anyone out there who is having problems, and is maybe depressed about being overweight, I throw myself on the funeral pyre of this site in the hopes that I might help someone.