The purpose of this study was to investigate the influence on the carbohydrate metabolism rhythm by the difference between various protein diets and feeding times. The rats were fed food three times per day; dietary patterns were combined casein diets and wheat protein diets. Plasma glucose, urea nitrogen and triglyceride were shown circadian rhythms that were related to the food intake. On the other hand, the hepatic and muscle glycogen were shown the clear circadian rhythms in the dietary pattern of evening-casein diet. The importance of supper was suggested. It clarified the combination of dietary proteins and the difference of feeding times influenced glycogen metabolism while the feeding contents on the day were the same.