- acute increase in protein intake: on the second occasion, they will have received an isocaloric diet (55% carbohydrate, 30% fat, 15% protein) during 4 days. On the morning of the 5th day, they will be studied for 2 hours in basal, post absorptive conditions and over 6 hours following ingestion of a meal providing ca 12.5 kcal /kg body weight and containing 45% carbohydrate, 30% fat (of which 13% medium chain triglycerides (MCT) labeled with 13C3 trioctanoate, and 25% protein.