Abstract The properties of an ideal weight-reducing drug would be to produce a sustained decrease in body fat, to oppose the recidivism in obese patients and to improve compliance to dietary requirements. More specifically the drug would have to decrease hunger, be active in the long term, preferably produce no tolerance or rebound effects, and prevent any decrease in basal metabolic rate. Moreover, the drug should reduce the intake of dietary fat which is now regarded as a major cause of weight gain (and regain) [141. Can this be achieved? Can drug-induced appetite control be used to combat obesity? Some drugs have already demonstrated a capacity to adjust appetite so as to produce significant improvements in the pattern of eating and the control of body weight. What mechanisms are responsible for such an action and how can new drugs be developed so as to advance the pharmacological control of appetite?