Covert manipulation of the dietary fat to carbohydrate ratio of isoenergetically dense diets: effect on food intake in feeding men ad libitum.

OBJECTIVE

High-fat, high energy-density (HF, HED) diets promote an increase in energy intakes relative to low-fat lower-energy density diets (LF, LED). This study examined whether HF diets promote higher levels of energy intake when isoenergetically dense (IE) relative to LF (high carbohydrate) diets, as predicted by glucostatic and glycogenostatic models for energy intake regulation.

SUBJECTS

Six normal-weight healthy men [mean age (SD) = 37.33 (13.32 y) mean weight = 73.03 (5.14 kg), mean height = 1.80 (0.05 m)].

DESIGN

Six men were each studied three times (factorial design) during 14-d throughout which they had ad libitum access to one of three covertly-manipulated diets. The fat, carbohydrate (CHO) and protein in each diet (as % energy) were 20:68:12, [low-fat (LF)]; 40:48:12, [medium-fat (MF)]; 60:28:12 [high-fat (HF)], with 2-d maintenance (1.4 x BMR, MF) beforehand. Within each diet every item was of the same composition and offered as a 3-d rotating menu.

MEASUREMENTS

Energy and nutrient intakes, body weight, subjective pleasantness and satisfaction of the food.

RESULTS

Energy intakes were 10.69, 11.02 and 10.90 MJ/d on the LF, MF and HF diets respectively. The increase in energy intake that occurred in previous studies when the energy density of the diet was increased by addition of fat was not apparent when LF, MF and HF diets were of the same energy density.

CONCLUSION

Neither carbohydrate nor fat intake were tightly regulated. These data do not support an entirely glucostatic or glucogenostatic model of food intake regulation.