Conclusions Meta- analysis of data from prospect i ve cohort studies showed small , inconsistent and non-significant associations between sedentary behavior and body weight
Background The cumulative effect of too much sedentary behavior may contribute to  weight gain and obesity .
Objective The aim of this study was to conduct a systematic review and meta- analysis of prospect i ve cohorts and r and omized controlled studies to determine the association between sedentary  behavior  and body weight and obesity in adults .
American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults.
Overweight and obesity affects more than 66 % of the adult population and is associated with a variety of chronic diseases . Weight reduction reduces health risks associated with chronic diseases and is therefore encouraged by major health agencies . Guidelines of the National Heart , Lung , and Blood Institute ( NHLBI ) encourage a 10 % reduction in weight , although considerable literature indicates reduction in health risk with 3 % to 5 % reduction in weight . Physical activity ( PA ) is recommended as a component of weight management for prevention of weight gain , for weight loss , and for prevention of weight regain after weight loss . In 2001 , the American College of Sports Medicine ( ACSM ) published a Position St and that recommended a minimum of 150 min wk(-1 ) of moderate-intensity PA for overweight and obese adults to improve health ; however , 200 - 300 min wk(-1 ) was recommended for long-term weight loss . More recent evidence has supported this recommendation and has indicated more PA may be necessary to prevent weight regain after weight loss . To this end , we have reexamined the evidence from 1999 to determine whether there is a level at which PA is effective for prevention of weight gain , for weight loss , and prevention of weight regain . Evidence supports moderate-intensity PA between 150 and 250 min wk(-1 ) to be effective to prevent weight gain .  Moderate-intensity PA between 150 and 250 min wk(-1 ) will provide only modest weight loss . Greater amounts of PA ( > 250 min wk(-1 ) ) have been associated with clinical ly significant weight loss .  Moderate-intensity PA between 150 and 250 min wk(-1 ) will improve weight loss in studies that use moderate diet restriction but not severe diet restriction . Cross-sectional and prospect i ve studies indicate that after weight loss , weight maintenance is improved with PA > 250 min wk(-1 ) . However , no evidence from well- design ed r and omized controlled trials exists to judge the effectiveness of PA for prevention of weight regain after weight loss .  Resistance training does not enhance weight loss but may increase fat-free mass and increase loss of fat mass and is associated with reductions in health risk . Existing evidence indicates that endurance PA or resistance training without weight loss improves health risk . There is inadequate evidence to determine whether PA prevents or attenuates detrimental changes in chronic disease risk during weight gain
Conclusions Meta- analysis of data from prospect i ve cohort studies showed small , inconsistent and non-significant associations between sedentary behavior and body weight
Background The cumulative effect of too much sedentary behavior may contribute to  weight gain and obesity .
Objective The aim of this study was to conduct a systematic review and meta- analysis of prospect i ve cohorts and r and omized controlled studies to determine the association between sedentary  behavior  and body weight and obesity in adults .