The present invention provides a highly safe dietetic composition originating in green coffee beans by which excellent dietetic effects can be obtained and which contributes to the prevention and treatment of life style-related diseases such as diabetes. A dietetic composition characterized by comprising, as the active ingredient, a polar solvent extract of defatted green coffee beans. It is preferable that the above-described polar solvent extract is an extract obtained by using water-containing ethanol, still preferably water-containing ethanol having an ethanol concentration of from 40 to 90% (wt/wt). It is preferable that the above-described defatted green coffee beans are those obtained by extracting green coffee beans with N-hexane to thereby separate oily components therefrom. It isrecommended to combine the above-described dietetic composition with one or more members selected from among salacia extract, evening primrose extract, sesamine and garcinia. This dietetic composition is usable as a material for foods, drinks, drugs, or skin preparations for external use.