***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background —The prevalence of obesity in both adults and children is increasing rapidly . Obesity in children is independently associated with arterial endothelial dysfunction and wall thickening , key early events in atherogenesis that precede plaque formation . Methods and Results —To evaluate the reversibility of obesity-related arterial dysfunction and carotid intima-media thickening by dietary and /or exercise intervention programs , 82 overweight children ( body mass index , 25±3 ) , 9 to 12 years of age , were r and omly assigned to dietary modification only or diet plus a supervised structured exercise program for 6 weeks and subsequently for 1 year . The prospect ively defined primary end points were ultrasound-derived arterial endothelial function ( endothelium-dependent dilation ) of the brachial artery and intima-media thickness of common carotid artery . At 6 weeks , both interventions were associated with decreased waist-hip ratio ( P < 0.02 ) and cholesterol level ( P < 0.05 ) as well as improved arterial endothelial function . Diet and exercise together were associated with a significantly greater improvement in endothelial function  than diet alone ( P = 0.01 ) . At 1 year , there was significantly less thickening of the carotid wall ( P < 0.001 ) as well as persistent improvements in body fat content and lipid profiles in the group continuing an exercise program . Vascular function was significantly better in those children continuing exercise ( n=22 ) compared with children who withdrew from the exercise program ( n=19 ) ( P < 0.05 ) . Conclusions —Obesity-related vascular dysfunction in otherwise healthy young children is partially reversible with diet alone or particularly diet combined with exercise training at 6 weeks , with sustained improvements at 1 year in those persisting with diet plus regular exercise BACKGROUND The proportion of overweight adolescents has increased , but the behavioral risk factors for overweight youth are not well understood . OBJECTIVE To examine how diet , physical activity , and sedentary behaviors relate to overweight status in adolescents . DESIGN AND SETTING Baseline data from the Patient-Centered Assessment and Counseling for Exercise Plus Nutrition Project , a r and omized controlled trial of adolescents to determine the effects of a clinic-based intervention on physical activity and dietary behaviors . PARTICIPANTS A total of 878 adolescents aged 11 to 15 years , 42 % of whom were from minority background s. MAIN OUTCOME MEASURE Centers for Disease Control and Prevention body mass index-for-age percentiles divided into 2 categories : normal weight ( < 85th percentile ) and at risk for overweight plus overweight ( AR + O ) ( > or=85th percentile ) . RESULTS Overall , 45.7 % of the sample was classified as AR + O with a body mass index for age at the 85th percentile or higher . More girls from minority background s ( 54.8 % ) were AR + O compared with non-Hispanic white girls ( 42 % ) ( chi(2)(1 ) = 7.6 ; P = .006 ) . Bivariate analyses indicated that girls and boys in the AR + O group did fewer minutes per day of vigorous physical activity , consumed fewer total kilojoules per day , and had fewer total grams of fiber per day than those in the normal-weight group . Boys in the AR + O group also did fewer minutes per day of moderate physical activity and watched more minutes per day of television on nonschool days than normal-weight boys . Final multivariate models indicated that independent of socioeconomic status ( as assessed by household education level ) , girls had a greater risk of being AR + O if they were Hispanic or from another minority background ( odds ratio [ OR ] = 1.65 ; 95 % confidence interval [ CI ] , 1.09 - 2.49 ) and a reduced risk of being AR + O as minutes per day of vigorous physical activity increased ( OR = 0.93 ; 95 % CI , 0.89 - 0.97 ) . A low level of vigorous physical activity was the only significant risk factor for boys being AR + O ( OR = 0.92 ; 95 % CI , 0.89 - 0.95 ) . Analyses based on meeting behavioral guidelines supported these findings and showed that failing to meet the 60 min/d moderate to vigorous physical activity guideline was associated with overweight status for both girls and boys . In addition , boys who failed to meet sedentary behavior and dietary fiber guidelines were more likely to be overweight . CONCLUSIONS Of the 7 dietary and physical activity variables examined in this cross-sectional study , insufficient vigorous physical activity was the only risk factor for higher body mass index for adolescent boys and girls . Prospect i ve studies are needed to clarify the relative importance of dietary and physical activity behaviors on overweight in adolescence Thirty obese women were r and omly assigned to either 40 % [ severe energy restriction ( SER ) ] or 70 % [ moderate energy restriction ( MER ) ] of their maintenance energy requirements and to no exercise , aerobic exercise ( walking ) , or aerobic exercise plus circuit weight training .  Body composition by hydrostatic weighing and energy expenditure by indirect calorimetry were measured at 0 , 3 , and 6 mo . In addition , we developed a deficit-efficiency factor ( DEF ) , calculated as body energy loss/dietary energy deficit , to attempt to quantify the effectiveness of the weight-reduction interventions . Subjects in the SER group lost more weight ( mean + /- SE : 15.1 + /- 1.4 vs 10.8 + /- 1.0 kg ) , fat ( 11.7 + /- 1.1 vs 8.3 + /- 0.6 kg ) , and fat-free mass ( 2.8 + /- 0.3 vs 1.8 + /- 0.3 kg ) than the MER group ( P < or = 0.05 ) . However , the overall DEF was greatest in the MER group ( 0.80 + /- 0.07 ) compared with the SER group ( 0.52 + /- 0.05 ; P < or = 0.01 ) . Exercise had no significant effect . This study demonstrates that MER may offer an advantage over SER because it produces a greater energy loss relative to energy deficit BACKGROUND Little is known about how the intensity of exercise influences cardiovascular fitness and body composition , especially in obese adolescents . OBJECTIVE Our goal was to determine the effects of physical training intensity on the cardiovascular fitness , percentage of body fat ( % BF ) , and visceral adipose tissue ( VAT ) of obese adolescents . DESIGN Obese 13 - 16-y-olds ( n = 80 ) were assigned to 1 ) biweekly lifestyle education ( LSE ) , 2 ) LSE + moderate-intensity physical training , or 3 ) LSE + high-intensity physical training . The intervention lasted 8 mo . Physical training was offered 5 d/wk , and the target energy expenditure for all subjects in physical training groups was 1047 kJ ( 250 kcal)/session . Cardiovascular fitness was measured with a multistage treadmill test , % BF with dual-energy X-ray absorptiometry , and VAT with magnetic resonance imaging . RESULTS The increase in cardiovascular fitness in the high-intensity physical training group , but not in the moderate-intensity group , was significantly greater than that in the LSE alone group ( P = 0.009 ) ; no other comparisons of the 3 groups were significant . Compared with the LSE alone group , a group composed of subjects in both physical training groups combined who attended training sessions > or=2 d/wk showed favorable changes in cardiovascular fitness ( P < 0.001 ) , % BF ( P = 0.001 ) , and VAT ( P = 0.029 ) . We found no evidence that the high-intensity physical training was more effective than the moderate-intensity physical training in enhancing body composition . CONCLUSIONS The cardiovascular fitness of obese adolescents was significantly improved by physical training , especially high-intensity physical training . The physical training also reduced both visceral and total-body adiposity , but there was no clear effect of the intensity of physical training BACKGROUND No studies have been reported in children that assess correlates of body-composition changes in response to a physical training intervention . OBJECTIVE The hypothesis studied was that variation in diet and physical activity would explain a significant portion of the interindividual variation in the response of body composition to physical training . DESIGN The participants were 71 obese children aged 7 - 11 y ( 22 boys , 49 girls ; 31 whites , 40 blacks ) .  Body composition was measured by dual-energy X-ray absorptiometry , physical activity by a 7-d recall interview , and diet by two , 2-d recalls . The children underwent 4 mo of physical training . RESULTS The mean attendance was 4 d/wk , the mean ( + /-SD ) heart rate for the 40-min sessions was 157 + /- 7 beats/min , and the mean energy expenditure was 946 + /- 201 kJ/session . On average , the percentage body fat decreased significantly in the total group , and total mass , fat-free soft tissue , bone mineral content , and bone mineral density increased , but there was a good deal of individual variability . Multiple regression models indicated that in general , more frequent attendance , being a boy , lower energy intake , and more vigorous activity were associated with healthier body-composition changes with physical training . Ethnicity was not retained as a correlate of the change of any component of body composition . CONCLUSIONS In obese children , age , vigorous activity , diet , and baseline percentage body fat together accounted for 25 % of the variance in the change in percentage body fat with physical training BACKGROUND Little is known about the effects of physical training on plasma leptin concentrations in children . OBJECTIVE We sought to determine the effects of 4-mo periods with and without physical training on leptin in obese children and to explore the determinants of leptin at baseline and in response to physical training . DESIGN Participants were 34 obese 7 - 11-y-old children r and omly assigned to engage in physical training during either the first or second 4 mo of the 8-mo study . RESULTS Total body composition , visceral adiposity , and insulin were all positively correlated with leptin at baseline ( P < or = 0.05 ) ; however , only fat mass was retained in the final stepwise regression ( P = 0.0001 , R2 = 0.57 ) . Leptin decreased during the 4-mo periods of physical training and increased in the 4 mo after cessation of physical training ( P < 0.001 for the time by group interaction ) . Decreases in leptin were greatest in children with higher pretraining leptin concentrations , those whose total mass increased least , and those whose insulin concentrations decreased most ( P < or = 0.05 ) ; only pretraining leptin concentration ( P = 0.009 ) and change in total mass ( P = 0.0002 ) were retained in the final regression ( R2 = 0.53 ) . CONCLUSIONS In obese children , leptin concentration decreased during 4 mo of physical training and increased during a subsequent 4-mo period without physical training , fat mass was highly correlated with baseline leptin , and greater reductions in leptin during 4 mo of physical training were seen in children with higher pretraining leptin and in those whose total mass increased least Exercise has been found to be effective for prevention of weight gain and maintenance of a stable weight in adults . The objective of this study was to evaluate the effect of a school-based aerobic exercise program on the obesity indexes of preschool children . Subjects were 292 second-year elementary school pupils from 2 kindergartens in Hat Yai municipality , Songkhla province , southern Thail and . A specially design ed exercise program , including a 15-min walk before beginning the morning class and a 20-min aerobic dance session after the afternoon nap , 3 times a week , was conducted for 29.6 wk . Weight , height , and triceps skinfold thickness were measured 4 times . At the end of the study , the prevalence of obesity , using 95th percentile National Center for Health Statistics triceps-skinfold-thickness cutoffs , of both the exercise and control groups decreased . That of the exercise group decreased from 12.2 % at baseline to 8.8 % ( Wilcoxon signed-rank test , P = 0.058 ) , whereas that of the control group decreased from 11.7 % to 9.7 % ( Wilcoxon signed-rank test , P = 0.179 ) . A sex difference in the response of body mass index ( BMI ) to exercise was observed . Girls in the exercise group had a lower likelihood of having an increasing BMI slope than the control girls did ( odds ratio : 0.32 ; 95 % CI : 0.18 , 0.56 ) . In conclusion , our study suggests that a 29.6-wk school-based exercise program can prevent BMI gain in girls and may induce a remission of obesity in preschool-age children INTRODUCTION The purpose of this study was to test the hypothesis that physical training ( PT ) , especially high-intensity PT , would have a favorable effect on components of the insulin resistance syndrome ( IRS ) in obese adolescents . METHODS Obese 13- to 16-yr-olds ( N = 80 ) were r and omly assigned to one of the following 8-month interventions ; 1 ) lifestyle education (LSE)-alone every 2 wk , 2 ) LSE+moderate-intensity PT , and 3 ) L 
    Output:
    
Conclusions : Based on the small number of short-term r and omized trials currently available , an aerobic exercise prescription of 155–180 min/weeks at moderate-to-high intensity is effective for reducing body fat in overweight children/adolescents , but effects on body weight and central obesity are inconclusive .