1,722,496 research outputs found
Increased fat oxidation in prepubertal obese children: a metabolic defense against further weight gain?
Full text linkThe purpose of this study was to measure postabsorptive fat oxidation at rest and to assess the association between fat mass and fat oxidation rate in prepubertal children, who were assigned to two groups: 35 obese children (weight, 44.5 +/- 9.7 kg; fat mass; 31.7 +/- 5.4%) and 37 nonobese children (weight, 30.8 +/- 6.8 kg; fat mass, 17.5 +/- 6.7%). Postabsorptive fat oxidation expressed in absolute value was significantly higher in obese than in nonobese children (31.4 +/- 9.7 mg/min vs 21.9 +/- 10.2 mg/min; p < 0.001) but not when adjusted for fat-free mass by analysis of covariance with fat-free mass as the covariate (28.2 +/- 10.6 mg/min vs 24.9 +/- 10.5 mg/min). In obese children and in the total group, fat mass and fat oxidation were significantly correlated (r = 0.65; p < 0.001). The slope of the relationship indicated that for each 10 kg additional fat mass, resting fat oxidation increased by 18 gm/day. We conclude that obese prepubertal children have a higher postabsorptive rate of fat oxidation than nonobese children. This metabolic process may favor the achievement of a new equilibrium in fat balance, opposing further adipose tissue gain
Fat intake and adiposity in 8- to 11-year-old obese children
No full textOBJECTIVE: To investigate the relationships between diet composition, body composition, and macronutrient oxidation at rest in obese and non-obese children. DESIGN: Cross-sectional study on fat intake, adiposity and postabsorptive macronutrients oxidation rates. SUBJECTS: 82 prepubertal (age: 9.1 +- 1.1 y) children, 30 obese (FM = 32.6 +- 6.1%) and 52 non-obese (FM = 15.6 +- 5.1%). MEASUREMENTS: Subcutaneous skinfold thicknesses for body composition, diet history for energy and nutrient intake, indirect calorimetry for resting metabolic rate (RMR) and RQ measurement. RESULTS: Energy intake (EI) was comparable in obese and non-obese children. Adjusted for RMR by ANCOVA, using RMR as the covariate, EI was significantly lower in obese than in non-obese children indicating either a blunted physical activity or a systematic underestimation of EI. Protein and carbohydrate intakes expressed as a percentage of total energy intake (%EI) were not significantly different in the two groups. Lipid intake (%EI) was slightly but significantly higher in the obese than in the non-obese group either unadjusted or adjusted for RMR by ANCOVA. The postabsorptive RQ was significantly lower in obese than in non-obese children. In the total group, %FM was weakly but significantly correlated to lipid intake (%EI). CONCLUSION: Obese prepubertal children have a higher relative fat intake than non-obese children and their FM is associated with this factor. The lower postabsorptive RQ of obese children may indicate a compensatory mechanism to achieve fat equilibrium by enhanced fat oxidation
Substrate metabolism, nutrient balance, and obesity development in children and adolescents: a target for intervention?
No full textObesity results from the organism's inability to maintain energy balance over a long term. Childhood obesity and its related factors and pathological consequences tend to persist into adulthood. A cluster of factors, including high energy density in the diet (high fat intake), low energy expenditure, and disturbed substrate oxidation, favour the increase in fat mass. Oxidation of three major macronutrients and their roles in the regulation of energy balance, particularly in children and adolescents, are discussed. Total glucose oxidation is not different between obese and lean children; exogenous glucose utilization is higher whereas endogenous glucose utilization is lower in obese compared with lean children. Carbohydrate composition of the diet determines carbohydrate oxidation regardless of fat content of the diet. Both exogenous and endogenous fat oxidation are higher in obese than in lean subjects. The influence of high fat intake on accumulation of fat mass is operative rather over a long term. Several future directions are addressed, such that a combination of increased physical activity and modification in diet composition, in terms of energy density and glycemic index, is recommended for children and adolescents
Effect of weight loss on resting energy expenditure in obese prepubertal children
No full textTo assess the effect of weight loss on resting metabolic rate (RMR), the energy expenditure of eight obese prepubertal children (age 9 ± 1 years; weight 48.7 ± 9.1 kg; BMI 25.3 ± 3.9) and of 14 age-matched children of normal body weight (age 9 ± 1 years; weight 28.8 ± 5.6 kg; BMI 16.5 ± 1.7) was measured by indirect calorimetry. The obese children were reinvestigated after a mean weight loss of 5.4 ± 1.2 kg induced by a six-months mixed hypocaloric diet. Before slimming, the obese group showed a higher daily energy intake than the control group (10.40 + 3.45 MJ/day vs 7.97 ± 2.02 MJ/day respectively; P < 0.05) but a similar value was observed per unit fat-free mass (FFM) (0.315 ± 0.032 MJ/kgFFM/day vs 0.329 ± 0.041 MJ/kgFFM/day respectively). The average RMR of the obese children was greater than that of the control group (5217 ± 531 kJ/day vs 4477 ± 506 kJ/day) but similar after adjusting for FFM (4728 ± 3102 kJ/day vs 4899 ± 3102 kJ/day). Weight loss resulted in a reduction in RMR (5217 + 531 kJ/day vs 4874 ± 820 kJ/day), each kg of weight loss being accompanied by a decrease of RMR of 64 kJ (15.3 kcal) per day. The changes in RMR induced by weight loss paralleled the changes in FFM. No difference was found in average RQ in obese children vs controls (0.85 ± 0.03 vs 0.87 ± 0.03 respectively) and in the obese children before and after weight loss (0.87 ± 0.02). After weight loss the absence of variation of RMR adjusted for FFM corroborates the notion that there are no modifications in the metabolic activity of FFM in obese children after slimming
Postprandial thermogenesis in obese children before and after weight reduction
No full textThe thermic effect of a meal (TEM) was measured in a group of 10 prepubertal obese children before (OB) and after (OA) weight reduction, and in a group of 10 age-matched control children (C) of normal body weight. Following a hypocaloric balanced diet for 6 ± 1 months, the obese children lost 5.2 ± 1.3 kg i.e. 11% of their initial body weight. The thermic response to the mixed liquid meal - fed at an energy level corresponding to 30% of the 24h premeal resting metabolic rate - was found to be significantly lower in OB than in C children (61 ± 25 kJ.3h-1 vs 79 ± 21 kJ.3h-1, P < 0.05), despite their higher test meal energy. After slimming, the TEM of obese children increased towards the controls' values (73 ± 30 kJ.3h-1). These results support the hypothesis of the existence of a moderate thermogenic defect in some obese children which represents a consequence rather than an aetiological factor of obesity
Entwicklung des energie-verbrauchs.
No full textDas lebensalter und das Geschlecht beinflussen alle KomponeDies ist durch verschiedene Faktoren erklarbar. Die wichtgsten dabei sind: 1. Das Verhältnis von organmasse zu Skelettmasse innerhalb der komponente fettfreie Korpermasse nimmt mit steigendem Lebersalter bei Kinder nab und deshalb verringert sich auch die metabische Aktiviät in Bezug auf die fettfreie Korpermasse mit dem Alter (Elia 2000); 2. Männliche Individuen haben eine großere Skeletmtmasse und eine niedrigere während und nach der Pubertät (Rico et al, 1993); 3. Das Maß der korperlichen Aktivität (ausgedruckt als PAL oder “physical activity level”: das Verhältnis zwischen Gasamtenergieverbrauch unf Grundumsatz) nimmt mit steigendem Lebensalter zu bis zu einer Phase vor der Pubertät bei beiden Geschlechtern. Bei Mädchen wird im Anschluss daran ein deutlicherer Ruckgang beobachtet als bei Junger (Maffeis 1999
Regulation des energiestoff-wechsels
No full textEine kurzlich veroffentlichte Studie zeigt, dass bei Kindern ca. 11% der postprandial oxidierten Fettmenge aus dem mit der Nahrung zugefuhrten Fett stammten und 89% aus endogenem, abgespeichertem Fett fur die Oxidation rekrutiert wurden (innerhalb von 9 h nach der Nahrungszufuhr unter Ruhebedingungen; Maffeis et al, 1999). Die Oxidation von exogenem Fett ausgedruckt als Anteil der gesanten Fettoxidation was direkt mit der Fettmasse des Korpers korreliert (r=0.56, pz0.03), wogegen die Oxidation von endogenem Fett ausgedruckt als Anteil der gesamten Fettoxidation invers mit dem Ausmass der Adipositas assoziiert was (r=-0.57, p<0.03). Die vermehrte Oxidation von exogenem Fett wahrend der Entstehung einer Adipositas kann als protektiver Mechanismus angesehen werden, der einer weiteren Zunahme der Fettmasse vorbeugt, wenn der Korper exogenem Fett im Rahmen einer Mahlzeit exponiert wirt
Total energy expenditure and patterns of activity in 8-10-year-old obese and nonobese children.
No full textTotal energy expenditure (TEE) and patterns of activity were measured by means of a heart rate (HR)monitoring method in a group of 8-10-year-old children including 13 obese children (weight, 46 +- 10 kg; fat mass: 32 +- 9%) and 16 nonobese children (weight, 31 +- 5 kg; fat mass, 18 +- 5%). Time for sleeping was not statistically different in the two groups of children (596 +- 33 vs. 582 +- 43 min; p = NS). Obese children spent more time doing sedentary activities (400 +- 129 vs. 295 +- 127 min; p lt 0.05) and less time in nonsedentary activities (449 +- 126 vs. 563 +- 135 min; p lt 0.05) than nonobese children. Time spent in moderate or vigorous activity-i.e., time spent at a HR between 50% of the maximal O-2 uptake (peak VO-2) and 70% peak VO-2 (moderate) and at a HR gtoreq 70% peak VO-2 (vigorous)-was not statistically different in obese and nonobese children (88 +- 69 vs. 52 +- 35 min and 20 +- 21 vs. 16 +- 13 min, respectively; p = NS). TEE was significantly higher in the obese group than in the nonobese group (9.46 +- 1.40 vs. 7.51 +- 1.67 MJ/day; p lt 0.01). The energy expenditure for physical activity (plus thermogenesis) was significantly higher in the obese children (3.98 +- 1.30 vs. 2.94 +- 1.39 MJ/day; p lt 0.05). The proportion of TEE daily devoted to physical activity (plus thermogenesis) was not significantly different in the two groups, as shown by the ratio between TEE and the postabsorptive metabolic rate (PMR): 1.72 +- 0.25 obese vs 1.61 +- 0.28 non-obese. In conclusion, in free-living conditions obese children have a higher TEE than do nonobese children, despite the greater time devoted to sedentary activities. The higher energy cost to perform weight-bearing activities as well as the higher absolute PMR of obese children help explain this apparent paradox
Energy expenditure during walking and running in obese and nonobese prepubertal children.
No full textWe measured body composition and energy expenditure during walking and running on a treadmill in 40 prepubertal children: 23 obese children (9.3 +/- 1.1 years of age; 46 +/- 10 kg (mean +/- SD)) and 17 nonobese matched control children (9.2 +/- 0.6 years of age; 30 +/- 5 kg). Energy expenditure was assessed by indirect calorimetry with a standard open-circuit method. At the same speed of exercise, the energy expenditure was significantly (p <0.01) greater in obese than in control children, in both boys and girls. Expressed per kilogram of body weight or per kilogram of fat-free mass, the energy expenditure was comparable in the two groups. Obese children had a significantly (p <0.01) larger pulmonary ventilatory response to exercise than did control children. Heart rate was comparable in boys and girls combined but significantly higher (p <0.05) in obese subjects, if boys and girls were analyzed separately. These data indicate that walking and running are energetically more expensive for obese children than for children of normal body weight. The knowledge of these energy costs could be useful in devising a physical activity program to be used in the treatment of obese children
- …
