ABSTRACT
To determine the effect of adiposity on adolescent energy expenditure compartments, basal energy expenditure (BEE) together with the thermic effect of food at rest and during post-exercise recovery were compared in eight lean (BMI < 25 kg/m2) and eight obese (BMI > 27 kg/m2) 15-year-old adolescent males at the same stage of pubertal development. Both groups were of equivalent fat-free mass. Continuous energy expenditure was measured by open circuit indirect calorimetry for periods of up to three hours following: (i) an overnight fast; (ii) a test meal; and (iii) moderate exercise after a further serving of the test meal. Repeat baseline measurements were taken on the following day. Absolute basal energy expenditure was higher in obese than in lean subjects. No significant differences were observed between groups in relation to BEE per kg total fat free-mass. Thermogenesis was significantly greater in the lean relative to the obese group under resting conditions (61.1 +/- 8.9 vs. 41.4 +/- 5.1 kcal/3h; P < 0.05) and in the post-exercise period (69.4 +/- 6.3 vs. 49.0 +/- 5.6 kcal/3h; P < 0.05). Of the body composition parameters, percentage fat mass was the best predictor of the thermic effect of food at rest (R = -0.53; P = 0.03) and post-exercise recovery (R = -0.61; P = 0.012). The results indicated that: (i) even when lean and obese adolescents are comparable with respect to fat-free mass, thermogenesis is blunted in obese subjects; and (ii) the best body composition predictor of thermogenesis in adolescents is percentage fat mass.
Subject(s)
Body Composition/physiology , Body Temperature/physiology , Energy Metabolism/physiology , Obesity/metabolism , Adolescent , Anthropometry , Eating/physiology , Exercise/physiology , Humans , Male , Reference ValuesABSTRACT
BACKGROUND: The ponderal evolution and biochemical parameters during the in patient administration of a highly hypocaloric and high protein diet (VLCD) were evaluated. The efficacy at medium term of this treatment was determined and the possible determining factors of the ponderal evolution were analysed. METHODS: A VLCD was administered to 20 women with morbid obesity during 21 days. The modifications of the biochemical parameters were determined during admission. The ponderal evolution was studied during hospitalization and during 9 months of out patient follow up. The prognostic factors of ponderal evolution analyzed were: age, attempts to lose weight, familiar history of obesity, maximum weight attained, weight and index of body mass (IBM) at study initiation and admission, loss of weight during admission and the number of out patient controls. RESULTS: During hospitalization, a mean loss of 7.0-1.9 kg, a significant decrease in glycemia, cholesterol, triglycerides, lymphocytes and blood pressure were observed. It was found that ponderal loss at 3 and 6 months may be predicted by IBM upon initiation of the study. At 9 months weight was lower than at initiation of hospitalization but not than at discharge (p < 0.001). Weight upon initiation of the study and the maximum reached explain the weight at 9 months in 82.5% of the cases. CONCLUSIONS: Highly hypocaloric and high protein diets lead to a significant weight loss which is maintained at medium term and an improvement in the factors of cardiovascular risk are observed. Of the factors evaluated, only the grade of obesity significantly influences ponderal evolution.