PURPOSE Cross-sectional studies show that individuals who walk more tend to be thinner than those who walk less. This does not mean, however, that the association between higher step counts and lower weight is causal or that encouraging sedentary individuals to increase step counts helps them lose weight. METHODSIn this meta-analysis, we searched 6 electronic databases and contacted pedometer experts to identify pedometer-based walking studies without a dietary intervention that reported weight change as an outcome. We included randomized controlled trials and prospective cohort studies published after January 1, 1995, in either English or Japanese, with 5 or more adult participants and at least 1 cohort enrolled in a pedometer-based walking intervention lasting at least 4 weeks. RESULTSNine studies met the study inclusion criteria. Cohort sample size ranged from 15 to 106, for a total of 307 participants, 73% of whom were women and 27% of whom were men. The duration of the intervention ranged from 4 weeks to 1 year, with a median duration of 16 weeks. The pooled estimate of mean weight change from baseline using a fi xed-effects model and combining data from all 9 cohorts was -1.27 kg (95% confi dence interval, -1.85 to -0.70 kg). Longer intervention duration was associated with greater weight change. On average, participants lost 0.05 kg per week during the interventions.CONCLUSION Pedometer-based walking programs result in a modest amount of weight loss. Longer programs lead to more weight loss than shorter programs. INTRODUCTIONO besity is increasing in prevalence among adults in the United States at an alarming rate. 1 The prevalences of type 2 diabetes 2,3 and other obesity-related chronic illnesses are increasing along with the prevalence of obesity. Both obesity and type 2 diabetes are preventable with diet and exercise modifi cations. 4 Cross-sectional observational studies have shown that people who walk more tend to be thinner than those who walk less. [5][6][7][8][9] In a typical pedometer-based walking intervention, participants are given a pedometer to wear every day, all day, as they go about their usual activities. Pedometers are small, inexpensive devices about the size of a pager that are worn at the waist and that count every step the wearer takes during the day. Participants are also given an assigned or negotiated total daily step-count goal. Pedometer-based walking programs show promise as an adjunct both in dietary weight loss interventions 10 and in preventing weight regain after substantial weight loss. 8,11 Most simple pedometers only provide feedback on total daily steps taken; feedback on intensity, duration, or frequency of walking is not provided. In contrast to walking programs that use time-based walking goals, pedometer-based walking programs make it possible to meet a relatively high step-count goal either by going for 1 long walk or by taking 70 WA L K ING IN T ERV EN T IONS A ND W EIGH T LOS Slots of very short walks spread throughout the day. It is in part the fl ex...