A Meta-Analysis of Pedometer-Based Walking Interventions and Weight Loss

Caroline R. Richardson, MD; Tiffany L. Newton, BS; Jobby J. Abraham, MBBS; Ananda Sen, PhD; Masahito Jimbo, MD, PhD, MPH; Ann M. Swartz, PhD

Disclosures

Ann Fam Med. 2008;6(1) 

In This Article

Discussion

The average participant in a pedometer-based walking program without dietary change can expect to lose a modest amount of weight, on the order of 1 kg. Results from the 9 cohorts we examined were remarkably consistent and did not vary by the population targeted or the goal-setting strategies used. These findings are consistent with previous research showing that increasing moderate-intensity physical activity tends to result in a modest amount of weight loss.[27,28,29,30]

The amount of weight loss attributable to pedometer-based walking programs is small but important from a clinical perspective. According to the meta-regression results, the average participant adhering to a pedometer-based walking program can expect to lose about 0.05 kg per week. That translates to a weight loss of about 1 lb every 10 weeks. Over a year, participants can expect to lose about 5 lb. Although a 5-lb weight loss for an overweight participant may represent only 2% to 3% of that person's body weight, if the participant continues with the pedometer program and if the rate of weight loss is sustained over several years, the target of 7% of body weight loss used in the Diabetes Prevention Program study[4] could be achieved.

Such modest amounts of weight loss, no matter how clinically important, may be discouraging to participants whose primary motivation for starting a walking program is to shed pounds. Unrealistic expectations of dramatic weight loss from such a program may result in early dropout. Helping participants set realistic and obtainable goals may be an important part of helping them stick with a walking program. Additionally, encouraging participants who are motivated by weight loss goals to add a dietary component to their walking program may yield more weight loss and thus may increase adherence.[10,31,32]

Average daily step-count increases varied from slightly less than 2,000 steps per day to more than 4,000 steps per day across these studies. For the average person, a 2,000-step walk is approximately equal to a 1-mile walk.[33] The daily increase in physical activity above baseline thus varied across these studies from an increase of 1 mile to slightly more than 2 miles of walking. At an average pace of 3 miles per hour, that represents an additional 20 to 40 minutes of walking a day and is in the range recommended by national guidelines.[34] This increase in physical activity can be expected to result in health benefits that are independent of weight loss. Increasing physical activity reduces the risk of adverse cardiovascular events,[31,35,36,37,38] lowers blood pressure,[23] and helps dieters maintain lean muscle tissue during diet-induced weight loss.[39] Additionally, a pedometer-based walking program can improve glucose tolerance in people with impaired glucose tolerance or type 2 diabetes.[23,40]

Unfortunately, we know very little about the long-term sustainability of weight loss from pedometer-based walking programs. More long-term studies of such programs are needed to better delineate their weight loss outcomes in that time frame.

There are several important limitations to this study. Because the analysis was based on preintervention-postintervention comparisons rather than on a comparison between randomized groups, there are a number of potential threats to validity, and the pooled estimate of approximately a 1.30-kg weight loss may either overestimate or underestimate the effect of the pedometer-based walking intervention. Participants who elect to join a walking program may be particularly motivated to change both their diet and exercise habits. Although none of the study interventions included in the meta-analysis had a dietary component, participants may have decreased their caloric intake on their own; therefore, the real cause of the weight loss might be dietary change rather than increased physical activity. To the extent that the weight loss observed in this review is attributable to participants' self-initiated diet changes, we would be overestimating the impact of the increased energy expenditure due to the pedometer-based walking program on weight loss. It would not take much of a change in dietary intake to cause a 1-kg weight loss. Only a study in which meticulous records of dietary intake are kept for all participants could ensure that the weight loss we observed was not due to changes in diet. Evidence supporting the theory that walking programs can result in weight loss includes the results of 1 study that examined preintervention and postintervention strength and fitness levels.[20] This study showed improved cardiorespiratory fitness and leg strength in addition to weight loss, suggesting that the exercise was of sufficient intensity to have a training effect.

It is more likely, however, that we have underestimated the impact of a pedometer-based walking program on weight loss. To the extent that individuals who did not start a walking program would have continued to slowly gain weight rather than maintain a stable weight, our weight loss estimate is lower than the actual change in weight attributable to the walking program. A large randomized controlled trial with a no-walking-program control arm for comparison would allow us to measure both the decreased weight gain and the weight lost from the walking program. The findings of a dose-response association with interventions that lasted longer resulting in larger amounts of weight loss adds evidence to our conclusion that the weight loss detected in this meta-analysis was in fact caused by the intervention itself.

In this study, we pooled the results from 9 cohorts of overweight or obese and sedentary individuals, all of whom participated in a pedometer-based walking program. All of the studies included in this meta-analysis were published since 2001, and most are preliminary investigations with small numbers of participants. As we learn more about pedometer-based walking programs and how to study them, both the quality of individual studies and the robustness of meta-analytic results will improve.

In conclusion, pedometer-based walking programs without a dietary intervention component do result in a modest amount of weight loss. Pedometer-based walking programs also do increase step counts and thus can be expected to confer health benefits that are associated with both a modest decrease in weight and an increase in physical activity.

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