Activity monitors may increase physical activity in overweight and obese adults, but effect on weight is unclear

Resident Focus - Volume 13, Issue 1

Reference: Obesity (Silver Spring) 2016 Oct;24(10):2078
Level 2 [mid-level] evidence

Fitness trackers are one of the latest fitness trends to hit the market. Many employers (including my university-based health system) are starting health initiatives which utilize fitness trackers to promote employee wellness. Activity self-monitoring and feedback are thought to increase motivation to be more physically active. It is not yet clear if trackers make a meaningful and objective difference in improving health outcomes, especially in certain populations where increased physical activity could lead to better health. In overweight and obese adults, do fitness trackers actually help to increase physical activity?

This systematic review examined 14 randomized trials including 1,157 overweight or obese adults aged 27-59 years, with median age of 44 years. The activity monitors used in each trial varied - 10 trials used pedometers, 3 trials used a web-based tracking system, and 1 trial used an accelerometer. Seven trials compared the use of behavioral physical activity intervention (BPAI) alone to BPAI plus an activity monitor. These trials evaluated total minutes of moderate-to-vigorous physical activity (MVPA), number of brisk walking minutes per week, and number of kilocalories expended per week as primary outcomes. The remaining 7 trials compared BPAI plus an activity monitor to a wait list group or usual care. Outcomes evaluated in these trials included number of steps per day and total minutes of MVPA. Trial durations ranged from 6 weeks to 1 year. Methodological limitations included quasi-randomization in 1 trial (work crews were randomized, rather than individual participants), unclear randomization (7 trials) and unclear allocation concealment (10 trials).

Compared to BPAI alone, BPAI plus activity monitor was associated with significantly increased brisk walking minutes per week in analysis of 2 trials with 54 women. There was also an increase in physical exercise kilocalories per week in analysis of 2 trials with 110 patients. There was no significant difference in total MVPA in analysis of 3 trials with 110 patients or change in body weight in analysis of 3 trials with 139 patients. Compared to usual care or wait list, BPAI plus activity monitor was associated with significant increases in both steps per day (in analysis of 4 trials with 417 patients) and total MVPA (in analysis of 3 trials with 651 patients). These trials did not report data for change in body weight.

This systematic review and meta-analysis is the first to analyze data regarding BPAI and use of activity monitors specifically for overweight and obese adults. Activity monitors in conjunction with behavioral physical activity interventions may increase physical activity in this population but their effect on patient-oriented outcomes, such as weight loss, is uncertain.

For more information, see the Physical activity for weight loss topic in Dynamed Plus. DynaMed users, see the Physical activity for weight loss topic in Dynamed Classic.

AMANDA L. RUSSELL, MD began her medical training at Eastern Virginia Medical School in Norfolk, Va., and is currently a third-year family medicine resident at the University of Virginia. Her interests include women’s health and geriatric medicine, with a particular interest in caring for the underserved. She has accepted a position at a federally-qualified community health center, which she will start this summer following her graduation from residency.

Faculty contributions by Katharine C. DeGeorge, MD, MS.

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