Despite the potential importance of weight gain to smoking relapse, in 1991 there had been virtually no success in eliminating, or even reducing, the weight gain following smoking cessation. Two promising pharmacologic methods for reducing postcessation weight gain were nicotine gum and an over-the-counter drug, phenylpropanolamine gum ([PPA]. However, the relative efficacy of these two drugs had never been evaluated and the mechanisms of action of both drugs on weight gain were unknown.