Objective: Weight loss is effective for improving cardiometabolic health in overweight and obese individuals, but can also result in areal bone mineral density (aBMD) losses and increased fractures. aBMD losses during weight loss may be attenuated by exercise. Our objective was to compare aBMD changes in overweight and obese adults undertaking weight loss alone, and in combination with exercise.
Methods: The Cochrane Central Register of Controlled Trials, PubMed, Web of Science, EMBASE and Scopus databases were searched for eligible articles until June 2020. Random effects meta-analyses determined mean difference (95% confidence intervals) in percentage aBMD change between groups.
Results: Nine randomised controlled trials (n=821) were included in the systematic review and six were included the meta-analysis (n=359). There were no significant differences between the weight loss alone and weight loss plus exercise groups for percentage changes in aBMD at the femoral neck (net difference: -0.72% [95%CI: -1.71, 0.26], P=0.15), lumbar spine (0.37% [95%CI: -0.32, 1.05], P=0.29) and whole-body (-0.27% [95%CI: -0.65, 0.12], P=0.17). Subgroup analyses revealed no differences in aBMD changes at any skeletal site in studies that used resistance exercise, aerobic exercise, or combined aerobic and resistance exercise during weight loss (all P>0.05). There were also no differences in aBMD changes in studies that were <6 versus >6 months in duration, or in studies that included individuals aged <60 versus >60 years.
Conclusion: This meta-analysis suggests that exercise does not attenuate aBMD losses during weight loss. However, very few included studies prescribed well-designed exercise interventions performed at sufficient intensities and for sufficient durations to maintain or improve aBMD. Additional long-term randomised controlled trials utilising targeted, osteogenic exercise interventions during weight loss, particularly in overweight and obese populations at risk for falls and fracture, are warranted.