The Nutty Professor (1996)

Professor Sherman Klump (Eddie Murphy) is a pleasant but hugely corpulent university professor doing genetic research into metabolism and weight loss. Rather incompetent in daily life, he is at least an expert in his field of science and his experimental formula shows great promise. However, when he meets the woman of his dreams, his colleague Professor Carla Purty (Jada Pinkett), he becomes fed up with his bulk and wants to impress her. In the hopes of losing weight, he tests his formula on himself, transforming into a suave but testosterone-fuelled womaniser whom he dubs "Buddy Love". Buddy is not like his alter-ego, however. He is rude and brash, driven by his artificially-raised testosterone, and gets into all sorts of trouble. He wants Carla for himself, although Carla would prefer the mild-mannered Sherman. Buddy is also not happy with the situation that requires him to turn back into Sherman when the formula wears off. He plots to overdose on the formula, which will permanently rid him of Sherman forever. Sherman must get to the formula before Buddy can use it, if he is not to lose himself and Carla as well.