title: The effect of a high-carbohydrate meal on postprandial thermogenesis and sympathetic nervous system activity in boys with a recent onset of obesity.
abstract: The purpose of the present study was to investigate the thermic effect of food (TEF) and sympathetic nervous system (SNS) activity in obese boys. Ten obese (9.2+/-0.4 years) and 13 lean boys (8.8+/-0.4 years) were examined for energy expenditure and fat oxidation measured via indirect calorimetry for 3 hours after a high-carbohydrate (HC; 70% carbohydrate, 20% fat, and 10% protein) or a high-fat (HF; 20% carbohydrate, 70% fat, and 10% protein) meal served on 2 different days at random. The activity of the SNS was assessed by means of a power spectral analysis of the heart rate variability. The TEF, expressed as a percentage of the consumed energy, was significantly lower in obese boys than in lean boys after the HC meal; however, such a difference was not observed after the HF meal. Multiple regression analysis revealed that obesity was a significant variable contributing to the variances in the TEF induced by the HC meal. Moreover, after the HC meal, the boys with a recent onset of obesity (duration, <3 years) manifested a lower TEF as well as a reduced very low frequency component of the heart rate variability, an index of thermoregulatory SNS functions, compared with the remaining obese and lean boys. In conclusion, obese boys possessed normal metabolic and sympathetic responses to the HF meal but showed a diminished thermogenic response to the HC meal, especially during the early phase of obesity.
authors.affiliation: Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Japan.
authors.forename: Narumi
authors.initials: N
authors.lastname: Nagai
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakane
authors.forename: Taku
authors.initials: T
authors.lastname: Hamada
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kimura
authors.forename: Toshio
authors.initials: T
authors.lastname: Moritani
mesh_terms: D000483:Alleles; D015992:Body Mass Index; D002153:Calorimetry, Indirect; D002352:Carrier Proteins / Q000235:genetics; D002648:Child; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004734:Energy Metabolism; D005502:Food; D005787:Gene Frequency; D006339:Heart Rate; D006801:Humans; D007473:Ion Channels; D050356:Lipid Metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D024101:Mitochondrial Proteins; D009765:Obesity / Q000503:physiopathology*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D016133:Polymerase Chain Reaction; D012044:Regression Analysis; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D022722:Thermogenesis / Q000502:physiology*; D000071256:Uncoupling Protein 1
chemical_list: D002352:Carrier Proteins; D004040:Dietary Carbohydrates; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1