Determining the amount of physical activity needed for long-term weight control

OBJECTIVE: To evaluate prospectively the influence of habitual physical act ivity on body weight of men and women and to develop a model that defines t he role of physical activity on longitudinal weight change. DESIGN AND SETTING: Occupational cohort study conducted for a mean of 5.5y. SUBJECTS: A total of 496 (341 male and 155 female) NASA/Johnson Space Cente r employees who completed the 3 month education component of the employee h ealth-related fitness program and remained involved for a minimum of 2y. MEASUREMENTS: Body weights were measured at baseline (T1) and follow-up (T2 ), and habitual physical activity was obtained from the mean of multiple ra tings of the 11-point (0-10) NASA Activity Scale (NAS) recorded quarterly b etween T1 and T2. Other measures included age, gender, VO2 max obtained fro m maximal treadmill testing, body mass index (BMI), and body fat percentage . RESULTS: Multiple regression demonstrated that mean NAS, T1 weight, aging a nd gender all influence long-term T2 weight. T1 age was significant for the men only. independently, each increase in mean NAS significantly (P < 0.01 ) reduced T2 weight in men (b= - 0.91 kg; 95% CI: - 1.4 to - 0.42 kg) and w omen (b = - 2.14 kg; 95% CI: - 2.93 to - 1.35 kg). Mean NAS had a greater e ffect on T2 weight as T1 weight increased, and the relationship was dose-de pendent. CONCLUSIONS: Habitual physical activity is a significant source of long-ter m weight change. The use of self-reported activity level is helpful in pred icting long-term weight changes and may be used by health care professional s when counseling patients about the value of physical activity for weight control.