The National Weight Control Registry (NWCR) was established in 1993 to examine characteristics of successful weight-loss maintainers. This group consistently self-reports high levels of physical activity. The aims of this study were to obtain objective assessments of physical activity in NWCR subjects and compare this to physical activity in both normal-weight and overweight controls. Individuals from the NWCR (n = 26) were compared to a never obese normal-weight control group matched to the NWCR group's current BMI (n = 30), and an overweight control group matched to the NWCR group's self-reported pre-weight-loss BMI (n = 34). Objective assessment of physical activity was obtained for a 1-week period using a triaxial accelerometer. Bouts of moderate-to-vigorous physical activity (MVPA) 10min in duration, as well as nonbout MVPA (bouts of MVPA 1-9min in duration) were summed and characterized. NWCR subjects spent significantly (P = 0.004) more time per day in sustained bouts of MVPA than overweight controls (41.5 35.1min/day vs. 19.2 18.6min/day) and marginally (P = 0.080) more than normal controls (25.8 23.4). There were no significant differences between the three groups in the amount of nonbout MVPA. These results provide further evidence that physical activity is important for long-term maintenance of weight loss and suggest that sustained volitional activity (i.e., 10min in duration) may play an important role. Interventions targeting increases in structured exercise may be needed to improve long-term weight-loss maintenance. © 2011 The Obesity Society.