Physical activity, total and regional obesity: dose-response considerations

Purpose: This review was undertaken to determine whether exercise-induced w eight loss was associated with corresponding reductions in total, abdominal , and visceral fat in a dose-response manner. Methods: A literature search (MEDLINE, 1966-2000) was performed using appropriate keywords to identify s tudies that consider the influence of exercise-induced weight loss on total and/or abdominal fat. The reference lists of those studies identified were cross-referenced for additional studies. Results: Total fat. Review of ava ilable evidence suggested that studies evaluating the utility of physical a ctivity as a means of obesity reduction could be subdivided into two catego ries based on study duration. Shea-term studies (less than or equal to 16 w k, N = 20) were characterized by exercise programs that increased energy ex penditure by values double (2200 vs 1100 kcal.wk(-1)) that of long-term stu dies (greater than or equal to 26 wk, N = 11). Accordingly, short-term stud ies report reductions in body weight (-0.18 vs -0.06 kg.wk(-1)) and total f at (-0.21 vs -0.06 kg.wk(-1)) that are threefold higher than those reported in long-term studies. Moreover, with respect to dose-response issues, the evidence from short-term studies suggest that exercise-induced weight loss is positively related to reductions in total fat in a dose-response manner. No such relationship was observed when the results from long-term studies were examined. Abdominal fat. Limited evidence suggests that exercise-induc ed weight loss is associated with reductions in abdominal obesity as measur ed by waist circumference or imaging methods; however, at present there is insufficient evidence to determine a dose-response relationship between phy sical activity, and abdominal or visceral fat. Conclusion: In response to w ell-controlled, short-term trials, increasing physical activity expressed a s energy expended per week is positively related to reductions in total adi posity in a dose-response manner. Although physical activity is associated with reduction in abdominal and visceral fat, there is insufficient evidenc e to determine a dose-response relationship.