Losing weight once it has been been gained is difficult, but worth trying for health benefits. If you diet, your body adapts to the lower caloric intake and becomes more efficient at utilizing and storing as fat any calories taken in. Thus, if you go off the diet, you gain weight even faster than before. The best diet is the one you continue to follow. Legitimate weight loss programs incorporate lifestyle changes that have more longer-lasting effects.
Weight tends to be gained with cessation of the drug use.
Sympathomimetic amines, principally amphetamines have been used for this purpose, but they fall out of favor because of the potential for abuse. Serotonin reuptake inhibitors such as fenfluramine and dexfenfluramine act to increase serotonergic activity by stimulating serotonin in brain synapses. On the basis of the serotonin hypothesis of appetite control, this would be expected to reduce appetite. The uncommon but potentially fatal side effects seen with dexfenfluramine of pulmonary hypertension and cardiac valvular sclerosis led to its removal from the market. It does not appear to affect the absorption of other nutrients or drugs.