***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: Increasing the precision of measurements of total energy expenditure in population -based epidemiological studies is important for accurately quantifying the relationship between this exposure and disease . Current question naire-based methods can not accurately quantify total energy expenditure , although they may provide an estimate of the frequency of vigorous activities . Heart rate monitoring with individual calibration has been advocated as a method for assessing energy expenditure in field studies and has been compared with the ' gold st and ard ' techniques of doubly-labelled water and indirect calorimetry . However the method has previously only been used on small and selected population s. This study was , therefore , established to test the feasibility of using heart rate monitoring in a population -based study of adults . A total of 167 individuals aged 30 - 40 years were r and omly selected and underwent 4 d heart-rate monitoring . Only three individuals could not complete the protocol . The mean physical activity level ( PAL ) measured over 4 d was 1.89 ( SD 0.40 ) in men and 1.76 ( sd 0.31 ) in women . There was no difference between mean PAL on weekend days compared with weekdays ( mean paired difference 0.0008 , 95 % CI -0.06 + 0.06 ) . The estimate of mean PAL was not correlated with BMI , percentage body fat or the waist : hip ratio . It was , however , correlated with cardio-respiratory fitness as measured by VO2(max ) per kg ( Spearman rank correlation coefficient 0.50 in men and 0.42 in women ) . The pattern of energy expenditure was assessed by calculating the percentage of daytime hours in which PAL was greater than five times basal energy expenditure . This measure was strongly correlated with the mean PAL in both men ( Spearman correlation coefficient 0.77 ) and women ( 0.71 ) . We conclude that heart-rate monitoring is a feasible method for assessing the pattern and total level of energy expenditure in medium-sized epidemiological studies . It may also prove useful as the reference technique for calibrating question naires to estimate energy expenditure in larger scale studies This report describes the proposed intervention and outcome measurement procedures for the Pathways study . Pathways is a multicenter school-based study aim ed at reducing the alanning increase in the prevalence of obesity in American Indian children . It is design ed as a r and omized clinical trial , involving approximately 2,00 third grade children in 40 schools in seven diferent American Indian communities . During a 3-year feasibility phase , which was just completed , the major components of the intervention ( school food service , classroom curriculum , physical education program , and family involvement ) were developed and pilot-tested . The measurement instruments for body composition ; physical activity ; dietary intake ; and knowledge , attitudes , and behavior were also developed and vali date d. Comprehensive process evaluation procedures also were defined . As of this writing , thefull-scale intervention program is being initiated and is scheduled to be completed in the spring of 200 . The primary aim of the Pathways intervention is to reduce average percent body fat in intervention-school children  by at least 3 % compared with control-school children by the end of the 3-year intervention . This goal is to be achieved primarily by an increase in physical activity and a reduction in the perceni of dietary fat intake . The program does not seek to reduce dietary energy intake . Rather , it is based on the assumption that a healthier ; lower-fat diet , combined with an increase in energy expenditure by increased physical activity , will result in fewer excess calories deposited as body fat OBJECTIVE : Since the prevalence of adult obesity is increasing in the United States , we examined the effect of changing common habits ( exercise , TV viewing , smoking and eating habits ) on four year change in body weight . DESIGN : A prospect i ve cohort study of US male health professionals with follow-up from 1988–1992 . Participants were 19 478 men aged 40–75 in 1986 , who were free of cancer , coronary heart disease , stroke and diabetes . METHODS : Multiple regression was used to determine the association between four year change in body weight ( from 1988–1992 ) and common habits , after adjusting for baseline age , hypertension and hypercholesterolemia . RESULTS : For middle aged men , vigorous activity was associated with weight reduction and TV/VCR viewing and eating between meals with weight gain . Quitting smoking and a history of voluntary weight loss prior to the study period were consistently related to weight increase . Recently being on a diet was more strongly associated with weight loss among older men . Over the four year follow-up period , middle-aged men who increased their exercise  , decreased  TV viewing  and stopped eating between meals  , lost an average weight of −1.4 kg ( 95 % confidence interval (CI)−1.6 – −1.1 kg ) , compared to a weight gain of 1.4 kg among the overall population . The prevalence of obesity  among middle-aged men was lowest among those who maintained a relatively high level of vigorous physical activity , compared to those who were relatively sedentary . CONCLUSION : These data suggest that improvement in the mix of health habits , particularly increasing vigorous activity , as well as decreasing TV use and changing eating habits , results in weight maintenance or a modest weight loss over four years Directly measured food intake in 31 overweight female smokers to test whether ( a ) calorie and carbohydrate intakes increase after smoking cessation and ( b ) double-blind d-fenfluramine ( 30 mg ) , a serotonin-releasing drug , suppresses weight gain , overeating , and dysphoric mood associated with stopping smoking . Placebo-treated patients grew dysphoric after smoking withdrawal and ate 300 kcal/day more from 2 to 28 days after , showing a 3.5-lb weight gain . Fat and protein intakes did not change , but carbohydrate intake increased ( 30 % to 40 % ) . D-fenfluramine prevented postcessation dysphoria . Although drug-treated patients ate more carbohydrate snacks just after quitting , they returned to baseline by 4 weeks , showing a 1.8-lb weight loss . Agents that enhance brain serotonin-mediated neurotransmission may help prevent weight gain , overeating , and dysphoric mood after smoking withdrawal OBJECTIVE This study examined the psychological consequences of a modest weight loss in a sample of healthy women aged 44 to 50 . METHOD Five hundred and thirty-five women , with body mass indices ( BMI s ) ranging from 20 to 34 , were r and omly assigned either to an intensive behavioral lifestyle intervention or to a no-treatment control group . Women in the lifestyle intervention received weight loss goals of 5 to 15 lb , depending on baseline BMI , and attended 20 weekly group meetings during which they received information on lowering dietary fat intake and increasing physical activity levels . Psychological measures administered at baseline and at a 6-month examination assessed perceived stress , mood , dietary restraint , and binge eating behaviors . RESULTS Intervention subjects showed significant decreases in depressive symptoms over time , relative to control subjects , and this effect was observed for normal-weight , as well as heavier , subjects . Binge eating scores for all subjects declined significantly over time , with heavier subjects in the intervention showing the greatest decrease in scores . DISCUSSION The current study found no evidence of negative psychological sequelae of participation in a behavioral lifestyle change program , regardless of weight status . Results further suggest that participation in these types of programs may exert a positive influence on the psychological status of both normal-weight and heavier women OBJECTIVE : To determine whether habitual leisure time physical activity and body mass change of working-aged men and women are associated . DESIGN : Prospect i ve 10 y follow-up study . SUBJECTS : A regionally representative cohort of 19–63 y old men ( n=2564 ) and women ( n=2695 ) in three municipalities in Finl and . MEASUREMENTS : The main outcome measures were average body mass change during the 10 y of follow-up and the clinical ly significant body mass gain defined as a body mass gain of 5 kg or more during the follow-up and a body mass index of 26 or higher at the end of the follow-up .  Leisure time physical activity  was determined from self-administered question naires . RESULTS : After adjustment for the potential confounders , the logistic regression analysis showed that the men and women with no regular weekly activity at the end of the follow-up had an odds ratio of 2.59 ( 95 % confidence interval , 1.69–3.97 ) and 2.67 ( 1.65–4.31 ) , respectively for clinical ly significant body mass gain in comparison with the most active groups . The men who had decreased their activity during the 10 y follow-up had an odds ratio of 1.96 ( 1.39–2.75 ) , and the men who were physically inactive all the time had an odds ratio of 1.62 ( 1.18–2.20 ) for clinical ly significant body mass gain when compared with the subjects who were active all the time . Among the women the odds ratios for clinical ly significant body mass gain after adjustment for potential confounders were 2.49 ( 1.72–3.60 ) and 1.61 ( 1.17–2.21 ) , respectively . CONCLUSION : These findings are consistent with the hypothesis that regular physical activity prevents body mass gain and physical inactivity is a risk factor for body mass gain and obesity among adults OBJECTIVE : To describe the design , methods , and first year results of the Pound of Prevention ( POP ) study , a r and omized trial examining whether weight gain with age can be prevented using low intensity intervention . DESIGN : Participants were r and omized to either ( 1 ) no-contact control , ( 2 ) education through monthly newsletters and semiannual classes on nutrition and exercise , and ( 3 ) education plus a lottery incentive for participation . SUBJECTS : Two hundred and twenty-eight men , 594 high-income women , and 404 low-income women . Entry requirements were age 20–45 y , healthy , and willing to participate for three years . MEASUREMENTS : At baseline and one year later , participants were weighed and completed question naires about behaviors and attitudes related to weight and weight control . RESULTS : Mean body mass indices at baseline were 28.1 , 26.1 , and 28.2 for men , high-income women and low-income women , respectively . After one year , participants in the intervention conditions reported significantly increased frequency of weight monitoring , but no change in other targeted behaviors . One year weight changes in the control , education , and education plus lottery groups were 1.94 lb , 0.72 lb , and 0.21 lb in men ; 1.38 lb , 1.03 lb , and 0.51 lb in high-income women ; and 1.30 lb , 2.11 lb , and 3.23 lb in low-income women . CONCLUSIONS : These one-year results suggest that the intervention may be having a greater impact on high than low-income participants Recent findings indicate that nearly 50 % of black American women are obese and that adolescence is a critical period for the development of their obesity . This study investigated the efficacy of a behavioral weight control program in 36 black female adolescents with a mean age of 14.0 years , weight of 95.0 kg , and height of 163.2 cm . All subjects participated in the same 16-week program but had different levels of parent participation : ( 1 ) child alone with no parent participation ; ( 2 ) mother and child treated in the same session ; and ( 3 ) mother and child treated in separate but concurrent session . At the end of the 16-week program , children in the three conditions lost 1.6 , 3.7 , and 3.1 kg , respectively . Differences among conditions were not statistically significant ; however , a secondary analysis revealed that the greater the number of sessions attended by mothers , the greater their daughters ' weight losses . Weight reduction was associated with significant improvements in body composition , serum total cholesterol concentrations , and psychological status . Results are discussed in terms of the need to improve the maintenance of weight loss in adolescents and to explore possible differences between black and white females in their preferred body types The effects of 12 weeks of home-based exercise training on peak oxygen consumption ( VO2 max ) in healthy sedentary middle-aged men , mean age 49 + /- 6 years , were evaluated . Twenty-one men trained at low intensity , 23 trained at high intensity and 20 were control subjects .  Individually prescribed low- and high-intensity training was performed 5 times per week within a range of 42 to 60 % and 63 to 81 % of baseline VO2 max , corresponding to average heart rates of 102 to 122 and 128 to 148 beats/min , respectively . Caloric expenditure per training session approximated 350 kcal in both groups ; adherence was at least 90 % in both groups . VO2 max increased 8 % in patients who trained at low intensity , 17 % in those who trained at high intensity ( both p less than 0.001 ) , and not at all in control subjects . Low-intensity exercise training at home significantly augments functional capacity in healthy sedentary middle-aged men The effectiveness of the  adolescent obesity intervention SHAPEDOWN was evaluated for 15 months through a r and omized experimental design study . Test groups ( no. = 37 ) participating in the intervention were compared with a no-treatment control group ( no. = 29 ) at four sites in northern California . The program employs a variety of cognitive , behavioral , and affective techniques adapted to make successive small modifications in diet , exercise , communication , and affect that are sustainable . Very-low-calorie or restrictive diets are avoided in the program . Parents are 
    Output:
    
Where diet and physical activity were described , positive effects were usually obtained , but all were measured by self-report .
Effects on weight were mixed but follow-up was generally short .
Smaller effects on weight gain were found among low-income participants , students and smokers .
Many participants in the community-based studies were overweight or obese .
Study dropout was higher among thinner and lower-income subjects .
CONCLUSION : Interventions to prevent weight gain exhibited various degrees of effectiveness .
Future interventions might be more effective if they were explicitly based on methods of behaviour change that have been shown to work in other context s. Effective interventions would be more easily replicated if they were explicitly described .
Effectiveness might be more precisely demonstrated if more objective measures of physical activity and diet were used , and if the follow-up was over a longer period