Meta-analysis: Effect of exercise, with or without dieting, on the body composition of overweight subjects
ABSTRACT To determine if physical training conserves fat-free mass (FFM) in overweight men or women during weight loss.
Journals published between 1966 and 1993 were searched by MEDLINE and by handsearch to obtain all reports on human subjects in which the effect of exercise on body composition was studied in at least two concurrent treatment groups, of which at least one group did, and one group did not, undergo an exercise programme designed to promote fat loss. The relation between loss of weight, and loss of FFM, was examined by linear regression analysis among exercising and non-exercising groups of men or women.
Twenty-eight publications reported results on 226 sedentary men in 13 groups, 233 exercising men in 14 groups, 199 sedentary women in 23 groups, and 258 exercising women in 28 groups.
Aerobic exercise without dietary restriction among men caused a weight loss of 3 kg in 30 weeks compared with sedentary controls, and 1.4 kg in 12 weeks among women, but there was little effect on FFM. Resistance exercise had little effect on weight loss, but increased FFM by about 2 kg in men and 1 kg in women. Regression analysis shows that for a weight loss of 10 kg by diet alone the expected loss of FFM is 2.9 kg in men and 2.2 kg in women. When similar weight loss is achieved by exercise combined with dietary restriction the expected loss of FFM is reduced to 1.7 kg in men, and women. It is probable that the FFM conserved by exercise during weight loss contains more water and potassium than average FFM. The subjects studied were not severely obese.
Aerobic exercise causes a modest loss in weight without dieting. Exercise provides some conservation of FFM during weight loss by dieting, probably in part by maintaining glycogen and water.
Full-textDOI: · Available from: C. Summerbell, Apr 08, 2015
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ABSTRACT: Globally, obesity is affecting an increasing proportion of children. Physical activity plays an important role in the prevention of becoming overweight and obese in childhood and adolescence, and reducing the risk of obesity in adulthood. Puberty and the following adolescent period are acknowledged as particularly vulnerable times for the development of obesity due to sexual maturation and, in many individuals, a concomitant reduction in physical activity. In many Western settings, a large proportion of children and adolescents do not meet recommended physical activity guidelines and, typically, those who are more physically active have lower levels of body fat than those who are less active. Active behaviours have been displaced by more sedentary pursuits which have contributed to reductions in physical activity energy expenditure. Without appropriate activity engagement there is an increased likelihood that children will live less healthy lives than their parents. Owing to the high risk of overweight adolescents becoming obese adults, the engagement of children and adolescents in physical activity and sport is a fundamental goal of obesity prevention.British Journal of Sports Medicine 09/2011; 45(11):866-70. DOI:10.1136/bjsports-2011-090199 · 5.03 Impact Factor
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ABSTRACT: The purpose of this study was to compare the amount of exercise prescribed with the amount completed between two different modes of training intervention and between the sexes. Thirty-two men (mean age = 39.1 years, body mass index = 32.9 kg x m(-2)) and women (mean age = 39.6 years, body mass index = 32.1 kg x m(-2)) were prescribed traditional resistance training or light-resistance circuit training for 16 weeks. Lean mass and fat mass were determined by dual-energy X-ray absorptiometry at weeks 1 and 16. A completion index was calculated to provide a measure of the extent to which participants completed exercise training relative to the amount of exercise prescribed. The absolute amount of exercise completed by the circuit training group was significantly greater than the amount prescribed (P < 0.0001). The resistance training group consistently under-completed relative to the amount prescribed, but the difference was not significant. The completion index for the circuit training group (26 +/- 21.7%) was significantly different from that of the resistance training group (-7.4 +/- 3.0%). The completion index was not significantly different between men and women in either group. These data suggest that overweight and obese individuals participating in light-resistance circuit training complete more exercise than is prescribed. Men and women do not differ in the extent to which they over- or under-complete prescribed exercise.Journal of Sports Sciences 04/2010; 28(6):633-40. DOI:10.1080/02640411003602027 · 2.10 Impact Factor
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ABSTRACT: Exercise expends energy, but without dietary intervention, exercise does not appear to produce substantial weight loss. The present study examined whether overweight, sedentary individuals increase their energy intake after moderate intensity exercise, particularly in the presence of negative mood. A repeated measures design was used where overweight, sedentary individuals (N=65) completed, in counterbalanced order, two conditions: 3 min of exercise (Active) and 3 min of sedentary activity (Sedentary) during one session. Snack foods were presented 10 min after each activity. Mixed-effects regression modeling revealed no significant effect of Active versus Sedentary condition on energy intake. However, moderational analyses revealed that change in negative mood interacted with condition to predict energy intake, such that participants who reported increased negative mood during exercise consumed more calories in the Active compared to the Sedentary condition. That a short bout of exercise resulted in mood deterioration and increased energy intake for some overweight, sedentary individuals is concerning. Further research examining behavioral and physiological mechanisms of mood deterioration and caloric overcompensation following exercise in overweight, sedentary individuals is warranted.Eating behaviors 02/2009; 10(1):29-35. DOI:10.1016/j.eatbeh.2008.10.009