Weight Loss Maintainers Ritualize a Time of Day for Exercise

Anyone who religiously goes to the gym at the same time of day—or does cardio on a particular outdoor route with day-in, day-out "temporal consistency"—knows that people who exercise in the morning, afternoon, or evening become creatures of habit. Like clockwork, you'll see the same "early risers" flocking to their local gym in the predawn hours, while a completely different group of "night owls" only seem to hit the gym after sundown. Most often, people's work schedules and personal chronobiology dictate what time of day "huffing and puffing" fits in and feels right.

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According to a new study (Schumacher et al., 2019), identifying a specific time of day (e.g., early morning, lunch break, after work, etc.) when you can consistently squeeze in some moderate-to-vigorous physical activity—and routinizing this "exercise time" into an automatic habit—is linked to better weight-loss maintenance. These findings by researchers affiliated with Brown University were published today in the journal Obesity.

When I first read the title of the news release for this study, "Timing of Exercise May Be Key to Successful Weight Loss," I incorrectly expected the research to show that the time of day someone worked out influenced his or her ability to lose weight successfully. The study's full title, "Relationship of Consistency in Timing of Exercise Performance and Exercise Levels Among Successful Weight Loss Maintainers," reflects the research findings more accurately. The focus of this research isn't really about how the timing of exercise influences successful weight loss, but rather on how forming consistent "same-time-of-day" exercise habits is associated with people sticking to a regular weekly workout routine and successfully maintaining previous weight loss.

What were the general findings? "In a study of 375 adults who successfully maintained weight loss and who engage in moderate-to-vigorous physical activity (MVPA), most reported consistency in the time of day that they exercised," the authors said.

Although daybreak was the most popular time for people in this study to seek exercise, so-called "weight loss maintainers" who preferred to work out in the afternoon or evenings (as part of a consistent daily habit) also experienced success in maintaining their weight loss.

Notably, over two-thirds (68 percent) of the people in this study who successfully maintained weight loss performed MVPA at the same time of day throughout the week. Additionally, these people were more likely to achieve the recommended moderate-to-vigorous physical activity guidelines (≥ 150 minutes) each week.

As the authors explain, "Temporal consistency was associated with greater MVPA, regardless of the specific time of day of routine MVPA performance. Consistency in exercise timing and other cues might help explain characteristic high physical levels among successful maintainers."

Of course, these findings are correlative; consistency in the timing of daily exercise performance is not some magic bullet that guarantees someone will instantly become a "successful weight-loss maintainer." There are multiple factors (e.g., caloric intake, diet quality, sleep habits, medication side effects, depression) that influence someone's ability to lose weight and keep it off. When it comes to successful weight loss maintenance, exercise is just one piece of a bigger—and very complex—puzzle.

"Our findings warrant future experimental research to determine whether promoting consistency in the time of day that planned and structured physical activity is performed can help individuals achieve and sustain higher levels of physical activity," senior author Dale Bond said in a statement. Bond is a professor of psychiatry and human behavior (research) at Brown's Alpert Medical School. First author Leah Schumacher added, "It will also be important to determine whether there is a specific time of day that is more advantageous for individuals who have initial low physical activity levels to develop a physical activity habit."

For more on the ins and outs of how aerobic exercise at different times of day can affect metabolism and sleep quality see "Morning and Evening Exercise May Burn Calories Differently" and "Easy-to-Moderate Exercise Before Bedtime Promotes Deep Sleep."