COVERT MANIPULATION OF ENERGY DENSITY OF HIGH-CARBOHYDRATE DIETS IN PSEUDO FREE-LIVING HUMANS

OBJECTIVE: This study examined the effects of varying the energy densi ty (ED) of high carbohydrate (HC) diets on food and energy intake (EI) , subjective hunger and body weight in humans. DESIGN: Randomised cros s-over design. Subjects were each studied twice during 14 d, throughou t which they had ad libitum access to one of two covertly-manipulated diets. SUBJECTS AND METHODS: Six healthy men (mean age (s.d.)= 32.17 y s.d. (5.26 y), mean weight = 69.74 kg s.d. (2.75 kg), mean height = 1 .76 m s.d. (0.05 m), body mass index (BMI) = 22.57 (2.2) kg/m(2)) were studied. The fat, carbohydrate (CHO) and protein content (as % energy ) and ED of each diet were 21 :66:13% and 357 kJ/100 g, (low-energy de nsity (LED)) or 22: 66: 12% and 629 kJ/100 g (high-energy density (HED )). A medium fat diet was provided at maintenance (1.6 x BMR, MF for 2 d) before each ad libitum period. Subjects could alter the amount, bu t not the composition of foods eaten. RESULTS: Mean El was 8.67 and 14 .82 MJ/d on the LED and HED diets, respectively Subjects felt signific antly more hungry on the LED diet, than on the HED diet (F1(,160)38.28 ; P < 0.001) and found the diets to be similarly pleasant (72.72 mm vs 71.54mm (F(1,392)0.31; P = 0.579)). Mean body weight decreased on the LED diet at a rate of 0.1 kg/d and increased at 0.06 kg/d on the HED diet (F(1,131)86.60; P < 0.001), giving total weight changes of - 1.41 kg and + 0.84 kg, respectively, both of which were significantly diff erent from zero (P < 0.01). CONCLUSION: Excess El is possible on HC, H ED diets, at least under conditions where diet selection is precluded. Comparison of these results with previous studies, which altered ED u sing fat, suggests that CHO may be a better cue for hunger than fat.