Covert manipulation of energy density of high carbohydrate diets in 'pseudo free-living' humans.
OBJECTIVE
This study examined the effects of varying the energy density (ED) of high carbohydrate (HC) diets on food and energy intake (EI), subjective hunger and body weight in humans.


METHODS
Randomised cross-over design. Subjects were each studied twice during 14 d, throughout which they had ad libitum access to one of two covertly-manipulated diets.


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/m2) 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 density (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, but not the composition of foods eaten.


RESULTS
Mean EI was 8.67 and 14.82 MJ/d on the LED and HED diets, respectively. Subjects felt significantly more hungry on the LED diet, than on the HED diet (F(1,160)38.28; P < 0.001) and found the diets to be similarly pleasant (72.72 mm vs 71.54 mm (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 different from zero (P < 0.01).


CONCLUSIONS
Excess EI is possible on HC, HED diets, at least under conditions where diet selection is precluded. Comparison of these results with previous studies, which altered ED using fat, suggests that CHO may be a better cue for hunger than fat.
Stubbs
R J
RJ
The Rowett Research Institute, Bucksburn, Aberdeen, UK.
Johnstone
A M
AM
Harbron
C G
CG
Reid
C
C
D000328:Adult; D001066:Appetite; D015992:Body Mass Index; D001835:Body Weight; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating; D002149:Energy Intake; D005518:Food Preferences; D006706:Homeostasis; D006801:Humans; D006815:Hunger; D008297:Male
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins