Larry Miller

Brilliant and obese scientist Sherman Klump invents a miraculous weight-loss solution. After a date with chemistry student Carla Purty goes badly, a depressed Klump tries the solution on himself. Though he instantly loses 250 pounds, the side effects include a second personality: an obnoxiously self-assertive braggart who calls himself Buddy Love. Buddy proves to be more popular than Sherman, but his arrogance and bad behavior quickly spiral out of control.

Scientist Sherman Klump's inventions, his upcoming marriage to his pretty colleague Denise Gaines, and his reputation, are threatened by his evil clone Buddy Love.