Responses to protein dilution in the adult female rat

Adult female rats were given ad lib access to 3 food cups containing casein, cornstarch, and a fat mixture, or a composite diet formulated from these nutrients. One-half of the animals in each diet condition were subjected to 25, 50, 150, and 500% sequential dilutions of the casein or the composite diet. Self-selecting rats decreased intake of the diluted casein, but increased consumption of cornstarch, so that total caloric intake remained constant. Composite-fed rats compensated for dilution by increasing the volume of diet consumed, but caloric regulation was less precise than in self-selectors.