Appetite Regulation in the Rat Under Various Physiological Conditions: The Role of Dietary Protein and Calories

Abstract

Rat dams fed isocaloric diets either high (25%) or low (8%) in protein content demonstrated three distinct phases of appetite regulation. During periods of mature growth (250-g female rats neither pregnant nor lactating) food intake was regulated by the caloric content of the diet alone. During pregnancy a 50% increase in food intake was seen in those rats fed the low (8%) protein diet. This resulted in identical weight gain for both the 8% and 25% protein-consuming dams during pregnancy. However, during lactation those rats consuming the 8% protein regimen did not compensate by increasing food intake, lost body weight and suckled pups which, at weaning, were approximately one-half the weight of those suckled by the mothers fed the 25% protein diet. By 10 days after weaning, all dams showed similar food intake and weight gain and returned to the eating pattern seen during mature growth. From these studies it is concluded that protein intake exerts a strong influence on energy requirements under conditions of physiological stress.