Energy metabolism in weight-stable postobese individuals.
A low metabolic rate for a given body size and body composition and a low ratio of fat to carbohydrate oxidation predict body weight gain. Such metabolic traits could also explain, in part, the propensity of previously obese (postobese) individuals to regain weight after dieting. We studied 11 postobese volunteers (4 males, 7 females; aged 43 +/- 13 y, weighing 80.6 +/- 10.2 kg, with 30 +/- 7% body fat; x +/- SD) who lost 57 +/- 38 kg (23-139 kg) over 14 +/- 12 mo (6-48 mo) on various diet programs and had maintained this weight loss for > or = 2 mo (2-72 mo; 21 +/- 27 mo). After > or = 2 d of a weight-maintenance diet on a metabolic ward, 24-h energy expenditure and ratio of fat to carbohydrate oxidation were measured in a respiratory chamber. Compared with a control group (n = 110) with similar physical characteristics (aged 43 +/- 14 y, weighing 79.5 +/- 11.4 kg, with 30 +/- 12% body fat), [sequence: see text] postobese individuals had similar energy expenditures adjusted for fat-free mass, fat mass, age, and sex, but significantly higher respiratory quotients over 24 h (0.883 +/- 0.026 compared with 0.863 +/- 0.024, P < 0.01) and during sleep, 10 h after the last meal (0.894 +/- 0.063 compared with 0.845 +/- 0.055). These results suggest that postobese individuals have low rates of fat oxidation that may explain their propensity to regain weight.(ABSTRACT TRUNCATED AT 250 WORDS)
Larson
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Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ, USA.
Ferraro
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Robertson
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Ravussin
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D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001823:Body Composition; D002153:Calorimetry, Indirect; D016022:Case-Control Studies; D004041:Dietary Fats / Q000378:metabolism; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D005082:Physical Exertion; D012307:Risk Factors; D015430:Weight Gain / Q000502:physiology; D015431:Weight Loss / Q000502:physiology*
D004041:Dietary Fats