The purpose of this study is to investigate the effects of intravenous infusion of two gastrointestinal hormones, PYY3-36 and GLP-1, alone and in combination, on appetite in healthy obese men. The investigators hypothesize that an intravenous infusion of each hormone alone will decrease food intake at a buffet meal and decrease appetite, and that in combination, there will be a greater decrease in food intake and appetite compared to each hormone alone.