大胖子科學家Sherman Klump教授發明了一種減肥化學藥物並利用自己當作實驗對象，卻意外變成內心深處身材苗條卻高傲自大的另一個名叫Buddy Love的人格。Obese scientist Professor Sherman Klump develops a weight-loss chemical and tests it on himself to become his slim and arrogant alter ego, Buddy Love.
