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It turns out that to lose weight more effectively, you should exercise between 7 and 9 a.m. A team of researchers from the University of Virginia reached this conclusion after analyzing data from a large-scale study involving 5,285 middle-aged Americans.
The scientists found that early risers who engage in morning workouts have a lower body mass index (BMI) and smaller waist circumference compared to those who exercise at noon or in the evening.
According to the researchers, morning workouts are optimal because it’s easier to stick to a schedule at that time. In the evening, people are more likely to get distracted by phone calls, emails, or meetings.
As noted by clinical psychologist Rebecca Krukowski, the lead author of the study, the effectiveness of weight loss also depends on whether you are a morning person or a night owl. Those who are used to waking up at dawn activate their circadian rhythms (biological clock) earlier, which positively impacts sleep quality and, consequently, weight loss.
What the Researchers Discovered
The scientists utilized data from the National Health and Nutrition Examination Survey (NHANES), which annually assesses the health of about 5,000 adults and children in the U.S. Their focus was on the results of a three-year study examining the impact of exercise on weight loss. During this extensive testing, each participant wore a fitness tracker (or accelerometer) on their hip.
The volunteers were divided into three groups based on their exercise times: morning (7:00-9:00), daytime (11:00-1:00), and evening (5:00-8:00). The first group included 642 individuals, the second had 2,400, and the third consisted of 2,187.
The researchers found that the morning group participants were 10 to 13 years older than those in the other two groups. Most of them had higher education, did not smoke, and did not consume alcohol. They also followed a healthier diet and ate less than the other participants.
The team collected data on BMI and waist circumference for each group and then drew conclusions about the relationship between weight loss and the time of day dedicated to exercise.
The morning group had the lowest BMI at 25.9 kg/m², which is slightly above the healthy range of 18.5-24.9 kg/m².
Participants in the daytime and evening groups showed similar results, with a BMI of 27.6 in the daytime group and 27.2 in the evening group. This indicates that they were overweight, as reported by the Daily Mail.
The average waist circumference for participants in the morning group was also the smallest at 91.5 centimeters. In contrast, the evening group had a waist circumference of 95 centimeters, while the daytime group measured 95.8 centimeters.
What Other Scientists Think
The study’s results were published in the journal Obesity. They confirmed and expanded upon findings from other research teams, as this is not the first attempt to establish a link between weight loss and the timing of exercise.
For instance, a 12-week study last year involving 100 adult volunteers from Skidmore College (U.S.) showed that women interested in losing weight should ideally exercise in the morning.
Another study conducted this year by researchers at the Karolinska Institute (Sweden) aligns with these conclusions. The authors of this study also claimed that morning workouts are best for combating excess weight. Interestingly, in this case, the researchers learned this not from humans but from mice, as the highest metabolism was observed in those animals that “exercised” in the early part of the day.
