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Background: Little is known about how daily fluctuations in health behaviors relate to chronic disease risk. The goal of this study was to examine whether variability in physical activity, caloric intake, and sleep is related to body composition (body mass index and body fat percentage). Methods: Healthy adults (N = 103; 64% female) were monitored for 7 days to assess physical activity (SenseWear Armband), caloric intake (daily food diaries), and sleep duration and timing (Actiwatch Spectrum). Data were analyzed using correlations (between- and within-subjects correlations) and regression. Results: The results demonstrated that variabilities in physical activity, caloric intake, and sleep were unrelated. Caloric intake and sleep variability were unrelated to body composition. At greater levels of physical activity variability, any level of physical activity was protective for body composition. Conclusions: These results suggest that among healthy adults, variabilities in health behaviors may be independent of each other, and physical activity variability may be more strongly related to body composition among those who are less active.
Hooker, Oswald, and Baron are with the Department of Behavioral Sciences, Rush University Medical Center, Chicago, IL. Hooker is currently at HealthPartners Institute, Minneapolis, MN. Oswald and Reid are with the Feinberg School of Medicine, Northwestern University, Chicago, IL. Baron is currently at the Department of Family & Preventive Medicine, University of Utah, Salt Lake City, UT.