DIFFERENTIAL-EFFECTS OF HIGH-FAT DIETS VARYING IN FATTY-ACID COMPOSITION ON THE EFFICIENCY OF LEAN AND FAT TISSUE DEPOSITION DURING WEIGHT RECOVERY AFTER LOW FOOD-INTAKE

The energetics of body weight recovery after low food intake was exami ned in the rat during refeeding for 2 weeks with isocaloric amounts of high-fat (HF) diets providing 50% of energy as either lard, coconut o il, olive oil, safflower oil, menhaden fish oil, or a mixture of all t hese fat types. The results indicate that for both body fat and protei n, the efficiency of deposition was dependent on the dietary fat type. The most striking differences were found (1) between diets rich in n- 3 and n-6 polyunsaturated fatty acids (PUFA), with the diet high in fi sh oil resulting in a greater body fat deposition and lower protein ga in than the diet high in safflower oil; and (2) between diets rich in long-chain (LCT) and medium-chain triglycerides (MCT), with the diet h igh in lard resulting in a greater gain in both body fat and protein t han the diet high in coconut oil. Furthermore, the diet high in olive oil (a monounsaturated fat) and the mixed-fat diet (containing all fat types) were found to he similar to the fish oil diet in that the effi ciency of fat deposition was greater (and that of protein gain lower) than with the diet high in safflower oil. Neither the efficiency of fa t gain nor that of protein gain were found to correlate with fasting p lasma insulin, the insulin to glucose ratio, or plasma lipids. The pre sent studies, conducted specifically under conditions of isocaloric re feeding after low food intake, demonstrate that the fatty acid composi tion of HF diets influences the recovery of both lean and fat tissue c ompartments-apparently by mechanisms unrelated to plasma insulin and l ipid status. The relevance of these findings is discussed in the conte xt of nutritional rehabilitation after undernutrition, as well as in t he context of dietary management of obesity relapse. Copyright (C) 199 5 by W.B. Saunders Company