Two recent studies on the use of exercise for obesity prevention and treatment found that the time of day individuals exercise may affect the success of weight loss and maintenance. Adults who consistently exercised in the morning were more successful in their weight-loss programs than those who exercised later in the day or those who mixed morning and evening sessions.
Even when individuals follow the same closely supervised exercise program for a set duration with no changes in diet, they do not all burn the same number of calories or lose the same percentage of body weight, according to Erik Willis, PhD, MPH, data analyst at University of North Carolina at Chapel Hill. Willis and colleagues conducted a secondary analysis from a previous randomized trial to determine the cause of this variability. In this trial, variation based on energy expenditure was removed by adjusting the length of exercise sessions so that all participants burned 400 to 600 calories per session. All participants had a weight loss goal of 5% of initial body weight.
The researchers did not recommend a time of day for exercising, but secondary data revealed that exercisers fell into one of three groups: early (more than 50% of sessions between 7 a.m. and noon), late (more than 50% of sessions between 3 p.m. and 7 p.m.) or sporadic (a mix of early and late). The results showed a correlation between the percentage of exercise sessions performed in the morning and increased weight loss: Early exercisers lost about 4% more body weight than late exercisers and about 2% more than the sporadic exercisers.
Additionally, 81% of early exercisers hit the 5% weight-loss goal vs. 54% of sporadic exercisers and 36% of late exercisers.
“All of the groups were losing weight,” Willis, told Endocrine Today. “The difference was the magnitude of weight that they were losing.”
Seth A. Creasy
In a separate study, Seth A. Creasy, PhD, a postdoctoral fellow at the University of Colorado Anschutz Medical Campus, and colleagues found, among other results, that the participants most successful at maintaining their weight loss were those who were highly active in the morning. These morning exercisers “were accumulating approximately 3,500 steps within the first 3 hours of waking up,” Creasy told Endocrine Today.
More to learn
Factors other than time of day for exercising, such as sleep duration and quality and food consumption, may have influenced results, Willis said.
“There is a lot to still look at in the future in an actual randomized control trial,” he said. “We do not know why the early exercisers chose to come in early.”
Additionally, Willis’ analysis counted those who exercised before noon as early exercisers, while Creasy’s trial defined morning as the time period within 3 hours of waking up.
“We cannot say that morning exercise is more effective; however, future studies should seek to understand any different effects based on the timing of exercise,” Creasy said.
Accessibility a necessity
Current recommendations for obesity prevention and treatment encourage individuals to exercise for 225 minutes or more per week for periods of at least 10 minutes at a time.
Although these recommendations can be effective to help individuals lose weight, they are likely to intimidate many who are unused to exercise, Creasy said.
“The problem is that not many people are able to engage in this recommended amount of physical activity,” Creasy said. “One of our focuses as researchers should be identifying strategies to enhance adherence to this recommendation.”
He added that consistency may be at least as important than morning exercise.
“Patients need to make their exercise routine a daily habit,” he said. “I would start them with a recommendation of just 10 minutes a day, 6 to 7 days per week. This would hopefully help with habit formation, and then I would slowly add time to their routine.”
He advises adopting an exercise program one enjoys, rather than one focused solely on weight loss, because such a routine is more likely to become habit.
Willis noted that recommendations have become less restrictive so that more people can attempt to follow them. Individuals who wish to lose weight should not limit themselves to morning exercise; rather, these study results should offer an additional tool to help tailor exercise programs on an individual basis.
“We need to get people moving, and something is better than nothing,” Willis said. “[People should] just get out there and start being active, and not worry about the details.” – by Amanda Alexander
Creasy SA. Daily and weekly patterns of physical activity influence body weight. Presented at: ObesityWeek 2018; Nov. 11-15, 2018; Nashville, Tenn.
Willis EA. Time of day influences of physical activity on body weight. Presented at: ObesityWeek 2018; Nov. 11-15, 2018; Nashville, Tenn.
For more information:
Seth A. Creasy, PhD, can be reached at firstname.lastname@example.org.
Erik Willis, PhD, MPH, can be reached at email@example.com.
Disclosures: Creasy reports his research was funded by the NIH. Willis reports no relevant financial disclosures.