Risperidone is known to cause a hormonal imbalance in teen boys, leading to this condition. The tits aren't made up of body fat. In fact, the tissue growth is more like what you find inside female tits. So, sort of a chemical-induced natural trooning. As far as I know, if you've got the RisperdalĀ® titties you're pretty much stuck with them unless you get surgery. No amount of fitness training will make them go away.
That sounds pretty fucked, but consider that Abilify (aripiprazole) has been shown to cause what is essentially a chemical lobotomy in some patients. The long term use of benzodiazepine (outlawed in most Western countries) can do even worse.