Human dietary responses to perceived manipulation of fat content in a midday meal.

The influence of knowledge about the macronutrient content of foods on dietary habits is poorly understood. The present study examined dietary responses to manipulations of information about the fat content of a midday meal provided to 17 free-living individuals. Following a one week baseline period, subjects were told that the meal provided each day for three 12-day blocks supplied a greater, lesser or equal amount of fat than their customary midday meal. They recorded daily intake. During the low-fat information period, subjects increased their total daily intake of energy relative to the high-fat period, their energy derived from protein relative to baseline and their energy derived from fat relative to all other periods. Information about the fat content of foods can influence food selection and should be considered when developing dietary interventions aimed at moderating fat intake.