Effects of time-restricted access to protein and of oral-sensory cues on protein selection.

The effects on protein consumption of restricting access to protein and of varying the oral-sensory properties of protein diets were measured. During the initial phase of the study, rats were maintained on a self-selection diet in which three different macronutrient sources (carbohydrate, fat, and either soy-based or casein-based protein diets) were continuously available. For the remaining 9 days of the study, half of the rats were protein deprived for 23 h each day and the other half continued to receive the same protein diet during this 23-h period. The remaining 1 h of each day was a test period in which all rats had access to a protein diet that was either the same as or different from the one they had received in the initial phase. Compared to the nonrestricted rats, the protein-restricted rats consumed diet during 1-h test periods. For the nonrestricted rats, those that received diet during 1-h test periods. For the nonrestricted rats, those that received a different protein diet during the 1-h test periods consumed 60% more of the protein diet than did those that received the same protein diet. These results indicate that increases in protein consumption following protein deprivation can be attributed, at least in part, to the oral-sensory properties of diets and not necessarily to a specific protein appetite.