Studies on the Metabolic Effects Induced in the Rat by a High Fat Diet. - I. Carbohydrate Metabolism In Vivo

Abstract

Rats were fed for three to five weeks after weaning a fat or a carbohydrate diet. Two fat diets were experimented and both of them induced in the rat a relative degree of obesity as indicated by the increased weight of epididymal fat pad. However, during the investigated period, mean daily caloric intakes were similar for carbohydrate diet and both fat diets. Serum glucose, insulin and free fatty acids (FFA), liver glycogen and fat were measured in the fed and starved states. Compared with control rats, fat-fed animals exhibited significantly higher glucose, lower insulin and higher FFA levels, almost double fat content and half reduced glycogen stores in the liver. In 24-hour starved animals, a 30% increase in glycemia was observed in fat-adapted rats compared with control rats, with normal insulin level and a lack of apparent fat mobilization.

Change from fat to carbohydrate diet resulted in normal caloric intake, but lowered food efficiency. In fed animals, FFA levels normalized quickly, serum insulin, liver glycogen and fat equilibrated rather speedily. Serum glucose remained significantly higher than control until five days after change of diet, showing that hyperglycemia is one of the major effects of fat diet.

Key words

Fat diet - Serum Glucose - Insulin - Liver Glycogen