What is the best time of day to exercise? If you want to lose weight or prevent weight gain, early morning moderate-to-vigorous physical activity (MVPA) ― between 7:00 AM and 9:00 AM ― may be the best time, according to a new study in Obesity.1
“The optimal time of the day to engage in MVPA for weight management is controversial,” wrote Tongyu Ma, lead author of the study. To study the timing of exercise, researchers examined data from 5285 participants of the National Health and Nutrition Examination Survey (NHANES), which included their exercise, eating, and lifestyle habits.
The daily exercise habits were broken into 3 categories: morning (n=642), midday (2456), and evening (2187). Among those who met the physical activity guidelines (≥ 150 minutes), the adjusted means for body BMI (kg/m2) were 25.9 (95% CI, 25.2–26.6), 27.6 (95% CI, 27.1–28.1), and 27.2 (95% CI, 26.8–27.7) in the morning, midday, and evening groups, respectively. Measurement of waist circumference (cm) were also lower in the morning exercise group: 91.5 (95% CI: 89.4–93.6), 95.8 (95% CI: 94.7–96.9), and 95.0 (95% CI: 93.9–96.1), respectively.
The researchers found that “people who did moderate to vigorous exercise in the morning had a lower BMI than people who exercised at midday or in the evening.” Overall, participants in the morning cluster were older (age 59.9, 49.9, 46.1, respectively) and female (57.8%, 47.3%, 45.4%, respectively). Self-reported dietary recall found that people in the morning group had a healthier diet and less daily energy intake per unit of body weight compared with the other two groups. Interestingly, the wearable accelerometry data “showed that participants in the morning cluster accumulated less physical activity but more sedentary behavior than did those in the midday and evening clusters.”
“Our findings substantiated the role of morning MVPA in weight management. However, owing to the observational nature of our data, it remains inconclusive whether morning MVPA is more effective than evening MVPA in reducing obesity,” the authors said. However, the current analysis seems to be supported by earlier studies. In a study by Willis et al,2 they “found a greater reduction in body mass and fat mass among participants who attended more than 50% of their training sessions in the morning compared with those who attended more than 50% of their training sessions between [3:00 PM and 7:00 PM].” Another study by Creasy et al,3 “found that a high amount of MVPA in the morning was a key feature of the physical activity pattern among successful weight loss maintainers, further supporting the important role of morning MVPA in weight management.”
Another interesting finding of the study is that “participants in the morning cluster spent a significantly higher amount of time on sedentary behavior than participants in the other clusters. However, despite the longer duration of sedentary time and the statistical adjustment for sedentary time, the favorable BMI and WC outcomes in the morning cluster persisted,” the authors wrote.
This study has limitations. The cross-sectional design of the study does not demonstrate temporal precedence. “Therefore, the causal relationship between the diurnal pattern of MVPA and obesity cannot be established. It is possible that the differences in BMI and WC cause the diurnal pattern of MVPA rather than the diurnal pattern causes changes of BMI and WC,” the authors report.
This article originally appeared on Clinical Advisor
1. Ma T, Bennett T, Lee CD, Wicklow M. The diurnal pattern of moderate-to-vigorous physical activity and obesity: a cross-sectional analysis. Obesity. 2023;31(10):2638-2647. doi:10.1002/oby.23851
2. Willis EA, Creasy SA, Honas JJ, Melanson EL, Donnelly JE. The effects of exercise session timing on weight loss and components of energy balance: Midwest Exercise Trial 2. Int J Obes (Lond). 2020;44(1): 114-124. doi:10.1038/s41366-019-0409-x
3. Creasy SA, Hibbing PR, Cotton E, et al. Temporal patterns of physical activity in successful weight loss maintainers. Int J Obes (Lond). 2021; 45(9): 2074-2082. doi:10.1038/s41366-021-00877-4