Failure of dietary fat intake to promote fat oxidation: a factor favoring the development of obesity.
Seven young men spent three nights and 2 d in a respiration chamber where their rates of energy expenditure and substrate oxidation were continuously measured by indirect calorimetry. During the first 24 h they ingested a mixed maintenance diet containing 35% of calories as fat. An additional amount of 106 +/- 6 g fat/24 h (means +/- SD) was added to this diet during the following 36 h. The fat supplement (987 +/- 55 kcal/d) did not alter 24-h energy expenditure (2783 +/- 232 vs 2820 +/- 284 kcal/d) and failed to promote the use of fat as a metabolic fuel (fat oxidation 1032 +/- 205 vs 1042 +/- 205 kcal/d). The overall energy balance was closely correlated with the fat balance (r = 0.96, p less than 0.001) but not with the carbohydrate balance (r = -0.12, NS). These data indicate that substantial imbalances between intake and oxidation are much more likely for fat than for carbohydrate.
Schutz
Y
Y
Institute of Physiology, Faculty of Medicine, University of Lausanne, Switzerland.
Flatt
J P
JP
Jéquier
E
E
D000328:Adult; D002153:Calorimetry, Indirect; D004032:Diet; D004040:Dietary Carbohydrates / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D004734:Energy Metabolism; D004837:Epinephrine / Q000652:urine; D015444:Exercise; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000652:urine; D009765:Obesity / Q000209:etiology*; D010084:Oxidation-Reduction
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D009638:Norepinephrine; D004837:Epinephrine