Learned caloric adjustment of human intake.

The time course of caloric compensation of food intake was studied in human subjects presented with a new calorically dilute snack food under naturalistic conditions. In a preliminary test, two versions of the snack food, normal in calories (NC) or low in calories (LC), were found equally palatable by the subjects (15 to 17-year-old boys). In the first part of the experiment two groups were presented with a 125g serving of either NC or LC version as an afternoon snack. Intakes during the subsequent dinner (1 h later) were measured. In the second part of the experiment, the same subjects were allowed to habituate to NC or LC, i.e. on five consecutive days, subjects were served NC or LC food ad libitum at afternoon snack-time; servings and left-overs were weighed. On the sixth day, the snack was a 125 g serving of the habitual food and dinner intakes were measured. It was shown that in these adolescent males a 200 kcal difference in the afternoon snack was not immediately compensated for by dinner intake. However, precise caloric adjustment occurred after habituation. This casts in question the value for weight control of such a use of food products having lower caloric content than conventional products.