Twenty-four hour energy expenditure and substrate oxidation before and after 6 months' ad libitum intake of a diet rich in simple or complex carbohydrates or a habitual diet.
OBJECTIVE
To investigate 24 h energy expenditure (24 h EE) and substrate oxidations in overweight and obese subjects before and after 6 months' ad libitum intake of a low-fat, high-simple carbohydrate diet (SCHO), a low-fat, high-complex carbohydrate diet (CCHO), or a habitual control diet (CD).


METHODS
Twenty-four healthy overweight and obese subjects (11 males and 13 females; body mass index 30.7+/-0.6 kg/m(2); age 42.2+/-1.8 y).


METHODS
Twenty-four hour EE, substrate oxidation rates and spontaneous physical activity (SPA) measured in a respiration chamber, and food intake.


RESULTS
After the intervention no differences were seen in 24 h EE, postprandial thermogenesis, basal metabolic rate or SPA. Carbohydrate oxidation, adjusted for energy balance, increased on both carbohydrate-rich diets (SCHO 13.0%, CCHO 11.5%) and decreased on the CD diet (6.5%); however, the changes were not significantly different between diets. The opposite pattern was seen for fat oxidation, which increased by 2.9% on the CD diet and decreased by 17.1 and 25.6% on the SCHO and CCHO, respectively. The changes only differed between the CD and CCHO diet (P=0.03).


CONCLUSIONS
Six months' ad libitum intake of a diet rich in simple or complex carbohydrates or a habitual diet induced a shift in the oxidation pattern to closely reflect the diet composition in overweight and obese subjects. No differences between diets were seen in 24 h EE.
Vasilaras
T H
TH
Research Department of Human Nutrition, Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark. thv@kvl.dk
Raben
A
A
Astrup
A
A
D000328:Adult; D002153:Calorimetry, Indirect; D004032:Diet; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D002149:Energy Intake; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism*; D010084:Oxidation-Reduction; D012119:Respiration; D013997:Time Factors
D004040:Dietary Carbohydrates; D004041:Dietary Fats