学龄儿童运动能量消耗与人体成分的关系

目的　探讨学龄期儿童运动能量消耗（AEE）与人体成分之间的关系。方法　以上海市杨浦区二联小学三、四年级62名学生为研究对象,使用代谢车测定运动能量消耗,利用生物电阻抗法测定人体成分,包括体质量、体质量指数、体脂率、脂肪含量、去脂体质量、脂肪含量指数、去脂体质量指数、肥胖度和AEE,比较超重肥胖组与非超重肥胖组儿童各指标的差异,并探讨其关系。结果　男生超重肥胖组和非超重肥胖组的运动时间［（9.70±1.91）min 比（10.00±1.97）min;t=0.336,P=0.739］、总AEE［（198.74±53.33）kJ 比 （171.54±41.75）kJ;t=-1.422,P=0.165］、AEE相对值［（0.46±0.09）kJ/(min·kg）比（0.51±0.04）kJ/(min·kg); t=2.043,P=0.051］差异均无统计学意义,超重肥胖组AEE绝对值高于非超重肥胖男生组［（20.06±3.14）kJ/min比（16.93±1.85）kJ/min;t=-2.910,P=0.007］。女生超重肥胖组与非超重肥胖组相比运动时间更短［（7.35±3.05）min 比 （9.98±1.82）min;t=2.509,P=0.027］、AEE相对值更小［（0.41±0.09）kJ/(min·kg）比 （0.51±0.07）kJ/(min·kg）;t=3.244,P=0.003］,但两组总AEE［（129.29±71.13）kJ 比 （161.50±35.38）kJ;t=1.351,P=0.203］、AEE绝对值［（16.82±3.26）kJ/min 比 （16.17±2.00）kJ/min; t=-0.676,P=0.504］差异均无统计学意义。控制年龄和性别因素后,男生AEE绝对值与体质量指数（P=0.015）、肥胖度(P=0.010)、脂肪含量(P=0.047)、去脂体质量(P=0.010）和去脂体质量指数(P=0.003)呈显著正相关,女生AEE绝对值与体成分各指标无相关性。AEE相对值与体质量指数（男：P=0.000,女：P=0.000）、肥胖度（男：P=0.002,女：P=0.000）、体脂率（男：P=0.000,女：P=0.001）、脂肪含量（男：P=0.000,女：P=0.000）、去脂体质量（男：P=0.002,女：P=0.022）和脂肪含量指数（男：P=0.000,女：P=0.000）呈显著负相关。结论　肥胖儿童AEE与体成分有关,肥胖程度越高,AEE相对值越少。儿童的体型、体成分与能量代谢存在着复杂的联系。     

Long-term changes in energy expenditure and body composition after massive weight loss induced by gastric bypass surgery

BACKGROUND: Little is known about the determinants of individual variability in body weight and fat loss after gastric bypass surgery or about the effects of massive weight loss induced by this surgery on energy requirements. OBJECTIVES: The objectives were to determine changes in energy expenditure and body composition with weight loss induced by gastric bypass surgery and to identify presurgery predictors of weight loss. DESIGN: Thirty extremely obese women and men with a mean (+/- SD) age of 39.0 +/- 9.6 y and a body mass index (BMI; in kg/m(2)) of 50.1 +/- 9.3 were tested longitudinally under weight-stable conditions before surgery and after weight loss and stabilization (14 +/- 2 mo). Total energy expenditure (TEE), resting energy expenditure (REE), body composition, and fasting leptin were measured. RESULTS: Subjects lost 53.2 +/- 22.2 kg body weight and had significant decreases in REE (-2.4 +/- 1.0 MJ/d; P < 0.001) and TEE (-3.6 +/- 2.5 MJ/d; P < 0.001). Changes in REE were predicted by changes in fat-free mass and fat mass. The average physical activity level (TEE/REE) was 1.61 at both baseline and follow-up (P = 0.98). Weight loss was predicted by baseline fat mass and BMI but not by any energy expenditure variable or leptin. Measured REE at follow-up was not significantly different from predicted REE. CONCLUSIONS: TEE and REE decreased by 25% on average after massive weight loss induced by gastric bypass surgery. REE changes were predicted by loss of body tissue; thus, there was no significant long-term change in energy efficiency that would independently promote weight regain.     

Relation between energy expenditure and body composition in man: specific energy expenditure in vivo of fat and fat-free tissue

The relationship between energy expenditure and body composition, in terms of fat and fat-free masses, has previously been described by a variety of predictive regression equations with parameters devoid of physiological content. We present here results obtained by calculating the specific energy expenditure, ie, the energy expenditure per unit of mass, of fat and fat-free tissue on the basis of measurements of the total energy expenditure (EE), the masses of fat (FM), and fat-free (FFM) tissue using the following simple model: EE = k1.FM + k2.FFM where k1 and k2 are the specific energy expenditures of fat and fat-free tissue, respectively. The results of observations on 104 women at rest yielded values for k1 and k2 of 0.31 and 1.35 watts/kg of fat and fat-free mass, respectively, with standard errors of estimate of 0.074 and 0.052 watts/kg, respectively. Analysis of several series of measurements, from other sources and on smaller samples of subjects, yielded similar values at rest but with larger standard errors of estimate. Data from subjects performing varying amounts of work in 24-h measurements showed, as expected, larger values for both tissues. The results explain to a very large extent the well-established relation between resting metabolic rate and body weight, ie, a linear relation with a non-zero intercept. The results also offer a clear-cut explanation for the well known difference in energy expenditure between men and women with the same body weight.     

Energy expenditure,body composition,and biochemical indicators in healthy community women

A cross-sectional study was conducted on the associations between energy expenditure (EE), body composition (lean mass, fat mass, body mass index), and biochemical indicators (leptin, glucagon, insulin, cortisol, and triglycerides) among 17 sedentary African-American and Caucasian women living in the community (age, 40.7±6.0 years; body mass index, 32.8±9.0 kg/m²). Measurements included total, resting, and sleeping EE (via whole-room indirect calorimetery), body composition (via air-displacement plethysmography), body mass index, and biochemical indicators (leptin, glucagon, cortisol, insulin, and triglycerides). Analysis of associations between EE and body composition showed that EE increased with increasing body size, with lean mass explaining 79%, 71%, and 73% of the variability in total, resting, and sleeping EE, respectively. Analysis of associations between body composition and the biochemical indicators showed that leptin, glucagon, and insulin were positively correlated with increasing body size, whereas cortisol was negatively correlated with increasing body size. Analysis of associations between EE and biochemical indicators prior to controlling for body size showed that leptin was positively correlated with EE, and that the correlation between leptin and sleeping EE was significantly greater than the correlation between leptin and resting EE. After controlling for body size, the correlations between leptin and EE were no longer significant, and the partial correlation between leptin and sleeping EE was no longer significantly different from the partial correlation between leptin and resting EE. Glucagon was positively correlated with EE, but not after controlling for body composition. Future research should incorporate the use of sleeping EE in addition to resting EE, since clearly, for some biochemicals such as leptin and glucagon, this distinction is important. Methodological improvements may provide better insight into the effects of obesity modulating hormones.     

Total and regional body composition and energy expenditure in multiple symmetric lipomatosis

AIMS: The aim of the present study was to investigate possible alterations in body composition and resting energy expenditure (REE) in type 1 multiple symmetric lipomatosis (MSL). SUBJECTS AND METHODS: Thirteen men aged from 40 to 78 years affected by type I MSL were compared with 13 healthy control subjects. Fat mass (FM) and fat-free mass (FFM) were determined by DEXA using both standard analysis and specifically for the lipomatous region. REE was measured by indirect calorimetry. RESULTS: FM was higher in MSL subjects at proximal arm level, but significantly lower at distal leg level than in controls (left 1.63+/-0.55 vs. 2.26+/-0.49 kg, P<0.05; right 1.63+/-0.53 vs. 2.40+/-0.54 kg, P<0.01). Arm FFM was similar in the two groups, while distal leg FFM was significantly lower in MSL cases (left: 7.8+/-1.3 vs. 8.7+/-0.8 kg, P<0.05; right: 8.0+/-1.5 vs. 9.2+/-0.9 kg, P<0.05). FFM strongly correlated with REE (r:0.86;P<0.001). REE, expressed as an absolute value and adjusted for FFM (1830+/-215 vs. 1675+/-120 kcal, P<0.05) was higher in MSL patients. CONCLUSION: In conclusion, MSL patients had a marked FFM and FM atrophy in the lower segments of the legs and an altered energy expenditure (hypermetabolism).     

Characteristics of body composition and resting energy expenditure in lean young women

The number of lean young women has been increasing. Fear of being fat may induce unnecessary attempts to reduce body weight, which can cause several types of illness. Many investigations have demonstrated dysfunction of the hypothalamus and metabolic differences in patients with anorexia nervosa. However, it is unclear whether there are any differences in physical characteristics between women with lower body weight and no illness compared to those of normal body weight. In this study, we investigated the differences in body composition, biochemical parameters, and resting energy expenditure (REE) between young women with low and normal body mass index (BMI). Twenty lean women (BMI<18.5 kg/m(2)) and 20 normal women (18.5≤BMI<25 kg/m(2)) were recruited for this study. Body composition, biochemical parameters, and REE (REEm: measurement of REE) were measured, and the REE (REEe: estimation of REE) was estimated by using a prediction model. Marked differences were found in body composition. All of the values of blood analysis were in the normal ranges in both groups. REEm (kcal/d and kcal/kg BW/d) was significantly lower in lean than in normal women, but there were no significant differences in the REEm to fat free mass (FFM) ratio between the two groups. In addition, there was good agreement between REEm and REEe obtained from the specific metabolic rates of four tissue organs. These data indicate that the lean women without any illness have normal values of biochemical parameters and energy metabolism compared to women with normal BMI.     

Energy expenditure, body composition, and biochemical indicators in healthy community women

A cross-sectional study was conducted on the associations between energy expenditure (EE), body composition (lean mass, fat mass, body mass index), and biochemical indicators (leptin, glucagon, insulin, cortisol, and triglycerides) among 17 sedentary African-American and Caucasian women living in the community (age, 40.7+/-6.0 years; body mass index, 32.8+/-9.0 kg/m2). Measurements included total, resting, and sleeping EE (via whole-room indirect calorimetery), body composition (via air-displacement plethysmography), body mass index, and biochemical indicators (leptin, glucagon, cortisol, insulin, and triglycerides). Analysis of associations between EE and body composition showed that EE increased with increasing body size, with lean mass explaining 79%, 71%, and 73% of the variability in total, resting, and sleeping EE, respectively. Analysis of associations between body composition and the biochemical indicators showed that leptin, glucagon, and insulin were positively correlated with increasing body size, whereas cortisol was negatively correlated with increasing body size. Analysis of associations between EE and biochemical indicators prior to controlling for body size showed that leptin was positively correlated with EE, and that the correlation between leptin and sleeping EE was significantly greater than the correlation between leptin and resting EE. After controlling for body size, the correlations between leptin and EE were no longer significant, and the partial correlation between leptin and sleeping EE was no longer significantly different from the partial correlation between leptin and resting EE. Glucagon was positively correlated with EE, but not after controlling for body composition. Future research should incorporate the use of sleeping EE in addition to resting EE, since clearly, for some biochemicals such as leptin and glucagon, this distinction is important. Methodological improvements may provide better insight into the effects of obesity modulating hormones.     

Total energy expenditure and physical activity level in healthy young Swedish children 9 or 14 months of age

OBJECTIVES: To measure total energy expenditure (TEE) and total body water (TBW) in healthy Swedish children 9 or 14 months of age. To compare their TEE with current recommendations for energy intake. To define their body composition and relate this to energy expenditure. DESIGN:: Children were investigated at 9 or 14 months. The following variables were measured: TEE and TBW (by the doubly labelled water method), weight and length. Total body fat (TBF), sleeping metabolic rate, activity energy expenditure and physical activity level (PAL) were calculated. SUBJECTS: Thirty infants 9 months of age and 29 children 14 months of age. RESULTS:: TEE was 323+/-38, 322+/-29, 313+/-23 and 331+/-28 kJ/kg/day in 9-month-old girls, 9-month-old boys, 14-month-old girls and 14-month-old boys, respectively. At 9 months of age girls and boys contained 29.6+/-4.8 and 29.7+/-4.5% TBF, respectively. At 14 months the corresponding figures were 29.1+/-4.3 and 28.2+/-4.3%. There was a significant negative relationship between PAL and %TBF (r=-0.81, P<0.001, n=59). CONCLUSIONS: Measured TEE plus calculated energy cost of growth confirm previous estimates that the physiological energy requirements of children 9 and 14 months of age are 15-20% lower than current recommendations for energy intake. One possible interpretation of the relationship between PAL and %TBF is that children with a high TBF content are less physically active than children with less TBF. However, this relationship needs further studies.     

Eight-year longitudinal changes in body composition in healthy Swiss adults

OBJECTIVE: Significant changes in body composition occur during lifetime. This longitudinal study (8.0 +/- 0.8 yrs) in a cohort of healthy sedentary and physically active men (n = 78) and women (n = 53), aged 20 to 74 yr describes: 1) the longitudinal changes in weight and body composition and 2) their associations with age and physical activity. Method: Fat-free mass (FFM) and body fat (BF) were assessed by bioelectrical impedance analysis (BIA). Subjects who regularly performed >3 hours per week of endurance type physical activity were classified as "Active". Others were classified as "Sedentary". Subjects were also separated by age (<45 yr vs > or =45 yr). RESULTS: FFM increased by 1.7 +/- 2.8 kg in men <45 yr who gained 4.0 +/- 5.0 kg of body weight and was maintained (0.5 +/- 1.6 kg) in women <45 y who gained 1.6 +/- 3.0 kg of weight. A weight gain of 1.2 +/- 3.3 kg in men > or =45 yr was accompanied by stable FFM (-0.1 +/- 2.3 kg), and of 1.0 +/- 3.2 kg was accompanied by a loss of FFM in women > or =45 yr. In active men > or =45 yr, maintenance of FFM was associated with smaller weight gains than in sedentary; sedentary men > or =45 yr decreased FFM with larger weight gains than active subjects. Sedentary women <45 yr were able to gain FFM; the active women maintained, but did not gain FFM with smaller weight gains than in sedentary women. FFM decreased in >/=45 yr women despite of small weight gains. CONCLUSION: Weight change is clearly associated with a change in FFM. Weight gain is necessary to offset age-related FFM loss between 20 and 74 yrs. In active men, a FFM increase was associated with less weight gain than sedentary men. Future studies should evaluate the threshold of weight change and the level of physical activity necessary to prevent age-related losses of FFM.     

Long-term effect of physical activity on energy balance and body composition.

We studied the effect of an increase in physical activity on energy balance and body composition without interfering with energy intake (EI). Sixteen women and sixteen men, aged 28-41 years, body mass index 19.4-26.4 kg/m2, not participating in any sport before the start of the experiment, prepared to run a half-marathon competition after 44 weeks. Measurements of body composition, EI and energy expenditure (EE) were performed before (0 weeks), and 8, 20, and 40 weeks after the start of training. Body composition was measured with hydrodensitometry and isotope dilution, and EI with a 7 d dietary record. EE was measured overnight in a respiration chamber (sleeping metabolic rate (SMR)) and in a number of subjects over 2-week intervals with doubly-labelled water (average daily metabolic rate (ADMR)). ADMR showed an average increase of 30% in both sexes from the start of training onwards while SMR tended to decrease. EI showed a tendency to drop from week 20 to week 40 in the men and a tendency to increase from week 20 to week 40 in the women. Body mass (BM) did not change in both sexes until the observation at 40 weeks when the median value of the change in men was -1.0 kg (P < 0.01; Wilcoxon signed-rank) while the corresponding change of -0.9 kg in the women was not statistically significant. Body composition changes were most pronounced in men as well. Based on changes in BM, body volume and total body water, men lost 3.8 kg fat mass (FM) (P < 0.001; Wilcoxon signed-rank) and gained 1.6 kg protein mass (P < 0.01; Wilcoxon signed-rank) while the corresponding changes in women were 2.0 kg (P < 0.05; Wilcoxon signed-rank) and 1.2 kg (P < 0.05; Wilcoxon signed-rank). In men the loss of FM was positively correlated with the initial percentage body fat (Pearson r 0.92, P < 0.001). In conclusion, body fat can be reduced by physical activity although women tend to compensate for the increased EE with an increased EI, resulting in a smaller effect on BM and FM compared with men.     

Validation study of energy expenditure and intake during calorie restriction using doubly labeled water and changes in body composition

BACKGROUND: Clinical trials involving calorie restriction (CR) require an assessment of adherence to a prescribed CR with the use of an objective measure of energy intake (EI). OBJECTIVE: The objective was to validate the use of energy expenditure (EE) measured by doubly labeled water (DLW), in conjunction with precise measures of body composition, to calculate an individual's EI during 30% CR. DESIGN: Ten participants underwent 30% CR for 3 wk. During the last week (7 d), 24-h EE was measured in a respiratory chamber and simultaneously by DLW (EEDLW). EI was calculated from 7-d EE measured by DLW and from changes in energy stores (ES) (weight and body composition). Calculated EI was then compared with the actual EI measured in the chamber by using the following equations: calculated EI (kcal/d) = EEDLW + DeltaES, where DeltaESFM/FFM (kcal/d) = (9.3 x DeltaFM, g/d) + (1.1 x DeltaFFM, g/d), FM is fat mass, and FFM is fat-free mass. RESULTS: We found close agreement (R = 0.88) between EE measured in the metabolic chamber and EEDLW during CR. Using the measured respiratory quotient, we found that the mean (+/-SD) EE(DLW) was 1934 +/- 377 kcal/d and EE measured in the metabolic chamber was 1906 +/- 327 kcal/d, ie, a 1.3 +/- 8.9% overestimation. EI calculated from EEDLW and from changes in ES was 8.7 +/- 36.7% higher than the actual EI provided during the chamber stay (1596 +/- 656 kcal/d). CONCLUSIONS: DLW methods can accurately estimate 24-h EE during CR. Although the mean difference between actual and calculated EIs for the group was small, we conclude that the interindividual variability was too large to provide an assessment of CR adherence on an individual basis.     

Plasma leptin association with body composition and energy expenditure in sickle cell disease

OBJECTIVE: To examine the association between fasting plasma leptin concentrations and the hypercatabolic state observed in sickle cell disease (SCD). METHODS: Plasma leptin concentration and resting energy expenditure (REE) were measured in 37 SCD patients (10 men, 12 boys 14 to 18 years-old, seven women, and eight girls 14 to 18 year-old) and in 37 age, gender and fat mass (FM) matched controls. Body composition was measured hydrostatically, REE by whole room-indirect calorimeter, and plasma leptin using an RIA kit. RESULTS: Plasma leptin concentration and leptin normalized for body fat (ng/dL*kg FM(-1)) were significantly lower in SCD patients than in non-SCD controls (4.00+/-3.23 vs. 9.94+/-14.69, p=0.021 and 0.406+/-0.260 vs. 0.643+/-0.561, p=0.024, respectively). A positive linear association between log plasma leptin and FM was observed in both males and females, adjusting for age and SCD status. The strength of this association was greater in females compared with males (slope=0.699 and 0.382 log ng/mL per 10 kg FM, respectively; p=0.013). SCD patients on average demonstrated a higher REE, adjusting for FFM (p<0.0001). Log plasma leptin and FM were not statistically significant predictors of REE after adjustment for FFM and SCD. CONCLUSIONS: Once corrected for body composition, mean plasma leptin concentration was significantly lower among female SCD patients than among non-SCD matched controls. Although REE was higher in SCD patients, there is no simple association between leptin and REE in SCD.     

Relation between body composition and age in healthy Japanese subjects.

OBJECTIVE: To describe the relation between body composition and age measured by dual-energy X-ray absorptiometry (DXA) in healthy Japanese adults. DESIGN: Cross-sectional study. SUBJECTS AND MEASUREMENTS: The subjects were 2411 healthy Japanese adults (males 625, females 1786, age 20--79 y) who attended the Fukuoka Health Promotion Center, Fukuoka, Japan for health check-up. Body composition was determined by DXA (QDR-2000, Hologic) for the whole body and three anatomical regions of arms, legs and trunk. RESULTS: The mean values of body mass index (BMI) and percentage fat mass (%FM) were 23.2+/-3.1 (s.d.) kg/m(2) and 21.8+/-6.8% for males and 22.1+/-3.3 kg/m(2) and 32.0+/-7.5% for females, respectively. For males, curvilinear relations with the peaks in their forties or fifties were seen for the variables associated adiposity, ie BMI, waist and hip circumference, waist-hip ratio, total or regional fat mass (FM), %FM and ratio of trunk FM to leg FM. For females, most of these variables increased linearly in older subjects. Lean mass (LM), bone mineral content (BMC) and bone mineral density (BMD) of the whole body and appendicular LM were relatively constant until the forties and then decreased in both sexes. The rates of decrease in the total or appendicular LM were larger for males than for females, whereas those in BMC or BMD were larger for females than for males. CONCLUSIONS: This study presents the first detailed data on body composition in Japanese, which may be useful when comparing with populations of different racial and ethnic backgrounds and studying ill subjects.     

Longitudinal changes in body composition, physical capacities and energy expenditure in boys and girls during the onset of puberty

BACKGROUND: The onset of puberty is a period of rapid anatomical and physiological alterations expected to induce changes in metabolic rate and energy requirements of children. AIM OF THE STUDY: To evaluate the changes in anthropometrical features, body composition, physical capacities, and energy expenditure (EE) of boys and girls during the period of onset of puberty. METHODS: Sixteen children (8 boys and 8 girls were recruited in the same school-class and studied both at 10.4 and 12.8 years of age. Body composition was assessed by bioimpedance analysis. Peak oxygen uptake (peak VO2) was measured using an automated on-line system during exercising on a cycle ergometer. Energy expenditure (EE) was determined by whole-body indirect calorimetry over a 24-h period after a 12-h period of adaptation to the calorimeters. Volunteers followed the same activity programme that included four 15-min periods of exercise. RESULTS: During the onset of puberty, boys and girls gained 4.7 +/- 2.1 kg x y(-1) (P < 0.0003) fat-free mass (FFM), whereas fat mass gain was 1.0 +/- 1.2 kg x y(-1) (P < 0.05) in girls and 0.20 +/- 0.66 kg x y(-1) in boys (NS). Peak VO2 adjusted for differences in FFM was not significantly affected by gender or pubertal stage. However, adjusted external mechanical power performed at peak VO2 was higher in pubertal than in prepubertal children, by 40% (P < 0.0001) and 22% (P < 0.003) in boys and girls, respectively. It was also 17% (P < 0.0002) higher in pubertal boys than in pubertal girls. Daily and sleeping EE increased by 38% and 32% in boys and girls, respectively, during the 2.4-y period (P< 0.0001). Adjusted EEs were also significantly higher in pubertal than in prepubertal boys (P< 0.05 and P< 0.003), but not in girls. The main significant determinants of daily EE were FFM (r2 = 0.866, P < 0.0001), peak VO2 (r2 = 0.017, P < 0.04), and age (r2 = 0.014, P < 0.05). Tanner's stage was an additional determinant of sleeping EE (r2 = 0.025, P < 0.006). CONCLUSIONS: The increases in physical capacities and EE during the onset of puberty indicated clear gender differences, which could be explained mainly by alterations of body composition in boys and girls, and by changes in hormonal status in boys. They also stressed the significant increase in energy requirements of children, especially boys, at an early stage of puberty.     

Regional changes in body composition by time of year in healthy postmenopausal women.

We examined regional changes in fat, lean, and bone tissue for greater than 1 y in 125 postmenopausal women. Duplicate whole-body scans were performed at 6-mo intervals. Period 1 was June or July to December or January and period 2 was December or January to the following June or July. Lean and bone tissue mass in the arms, legs, trunk, and whole body increased in period 1 and decreased in period 2 [eg, lean tissue in legs increased 1.84 +/- 0.41% (mean +/- SE) in period 1 and decreased 2.84 +/- 0.39% in period 2, P less than 0.001]. In each region except the arms, fat tissue decreased in period 1 and increased in period 2. Quadriceps muscle strength was correlated with lean tissue mass of the legs [rp (controlled for height) = 0.24, P V 0.02] and physical activity was correlated with quadriceps strength. Overall, body weight did not change significantly (0.17 +/- 0.41% increase, P greater than 0.20); however, there was a net loss of 1.08 +/- 0.39% (P less than 0.01) in lean tissue in the legs and a net increase of 3.43 +/- 1.12% (P less than 0.01) in fat tissue in the trunk.     

Body movement and physical activity energy expenditure in children and adolescents: how to adjust for differences in body size and age

BACKGROUND: Physical activity data in children and adolescents who differ in body size and age are influenced by whether physical activity is expressed in terms of body movement or energy expenditure. OBJECTIVE: We examined whether physical activity expressed as body movement (ie, accelerometer counts) differs from physical activity energy expenditure (PAEE) as a function of body size and age. DESIGN: This was a cross-sectional study in children [n = 26; (+/-SD) age: 9.6 +/- 0.3 y] and adolescents (n = 25; age: 17.6 +/- 1.5 y) in which body movement and total energy expenditure (TEE) were simultaneously measured with the use of accelerometry and the doubly labeled water method, respectively. PAEE was expressed as 1) unadjusted PAEE [TEE minus resting energy expenditure (REE); in MJ/d], 2) PAEE adjusted for body weight (BW) (PAEE. kg(-1). d(-1)), 3) PAEE adjusted for fat-free mass (FFM) (PAEE. kg FFM(-1). d(-1)), and 4) the physical activity level (PAL = TEE/REE). RESULTS: Body movement was significantly higher (P = 0.03) in children than in adolescents. Similarly, when PAEE was normalized for differences in BW or FFM, it was significantly higher in children than in adolescents (P = 0.03). In contrast, unadjusted PAEE and PAL were significantly higher in adolescents (P < 0.01). CONCLUSIONS: PAEE should be normalized for BW or FFM for comparison of physical activity between children and adolescents who differ in body size and age. Adjusting PAEE for FFM removes the confounding effect of sex, and therefore FFM may be the most appropriate body-composition variable for normalization of PAEE. Unadjusted PAEE and PAL depend on body size.     

Improvements in body composition, glucose tolerance, and insulin action induced by increasing energy expenditure or decreasing energy intake

Increases in exercise energy expenditure without compensatory changes in food intake (EX) and restriction of calorie intake (CR) both decrease body weight and fat mass, which, in turn, improve glucoregulatory function. However, EX may provide greater benefits than can be provided through CR. Therefore, our study hypothesis was that weight loss through EX reduces visceral abdominal fat and improves glucoregulation to a greater extent than does similar weight loss through CR. Forty-eight sedentary 50- to 60-y-old men and women, most of whom were overweight, underwent 12 mo of EX, CR, or a healthy lifestyle control period. Body composition was assessed by dual-energy x-ray absorptiometry and by magnetic resonance imaging. Indices of glucoregulatory function were determined by oral glucose tolerance test and were measured > or =48 h after the last exercise bout in the EX group. Body weight, total fat mass, and visceral fat volume decreased similarly in the EX and CR groups but did not change in the HL group. Likewise, insulin sensitivity index and the oral glucose tolerance test glucose and insulin areas under the curve improved similarly in the EX and CR groups and remained unchanged in the HL group. In conclusion, weight losses induced by exercise and by CR are effective means for improving glucose tolerance and insulin action in nonobese, healthy, middle-aged men and women; however, it does not appear that exercise training-induced weight loss results in greater improvements than those that result from CR.