Although the super-fat Professor Kings (played by Eddie Murphy) is academically intelligent and kind-hearted, he has always become a laughing stock of everyone because of his body size problem. Until one day, Professor Kings discovered that the new drug he had developed had been successful. This medicine could change the DNA of mice and make them lose weight. It seemed that Professor Kings was about to usher in a new life. Professor Kings has always been in love with Miss Carlow (played by Jada Pinkett Smith), a chemistry teacher. When he asked her to a club for dinner, Professor Kings was ridiculed by the host Rickey because of her body size problem, which made him unable to lift his head in front of his female partner. After returning, Professor Kings decided to drink the new drug he developed. After drinking the potion, a miracle happened, and Professor Kings became a debauchery, shameless, sinister and cunning thin guy. Fortunately, the duration of the potion was limited, and after a certain period of time, Bi Di became Professor Kings again. In order to hold his head in front of Carlo, Professor Kings drank the potion time and time again...