Associations between chronotype, weight loss, and adherence to caloric intake and physical activity goals during a behavioral weight loss intervention

Later chronotype (a later sleep/wake time pattern) has been associated with greater caloric intake, lower levels of physical activity, and higher body mass index (BMI); however, less is known regarding whether chronotype predicts changes in weight and weight-related behaviors during a weight loss program. These associations were examined in in 321 non-shift-working adults with obesity (M +/- SD age = 49.91 +/- 10.75 years; BMI = 35.86 +/- 4.07 kg/m(2); 84.7% women, 75.7% White) enrolled in a 16-week behavioral weight loss program. It was hypothesized that, after adjusting for age and gender, later chronotype at baseline (assessed via Munich Chronotype Questionnaire [MCTQ]) would predict less weight loss and that this association would be mediated by adherence to caloric intake and physical activity goals. Exploratory analyses examined associations between other MCTQ sleep variables (i.e., social jetlag, sleep duration, sleep loss) and weight loss. Participants lost an average (mean +/- SD) of 6.33 +/- 4.91% of their baseline weight during the intervention. Greater caloric intake and physical activity goal adherence were associated with greater weight loss, ps < 0.001. Later chronotype predicted lower physical activity goal adherence, p = 0.023; however, there were not significant associations between chronotype and caloric intake goal adherence or weight loss, ps > 0.05. Further, adherence to caloric intake and physical activity goals did not significantly mediate the effect of chronotype on weight loss. Finally, weight change was not predicted by any other MCTQ sleep variables, ps > 0.05. Taken together, results suggest that behavioral weight loss interventions may be similarly beneficial for individuals regardless of chronotype.