This is correct, no drug in the world can "make" you gain weight. It can lower your metabolism, yes, and it can make you hungry, yes, but NOTHING IN THE WORLD can break the Law of thermodynamics. However, a drug messing with your metabolism and increasing the hunger stimulus can make it VERY DIFFICULT not to gain weight, so I understand your frustration. Yet, if you count calories meticulously, and get some exercise, and weigh yourself regularly, you can control body-weight. The hard part is that you'll have to adjust your calories as your metabolism fluctuates, hence the regular weight-checks to make sure you are on track.