Researchers unveiled optimal time for engaging in physical exercise to achieve weight loss

According to research, individuals who frequent the gym after work may need to consider modifying their schedules. A study conducted in the United States on 5,285 middle-aged adults revealed that exercising between 7am to 9am was the optimal time for weight loss. Participants in this category exhibited a lower body mass index (BMI) and smaller waist circumference compared to those who exercised at midday or in the evening, despite spending more time sedentary than the latter group.

Scientists posit that morning exercise may be more effective due to the ease of adhering to a consistent schedule and the reduced likelihood of being distracted by phone calls, emails, or meetings. Dr. Rebecca Krukowski, a clinical psychologist at the University of Virginia, expressed enthusiasm for the research, stating that it aligns with the common recommendation of scheduling exercise in the morning before potential distractions arise. However, she acknowledged that other factors, such as having a more predictable schedule or not having caregiving responsibilities, may have contributed to the results.

She added: ‘Predictable schedules could have other advantageous effects on weight that were not measured in this study, such as sleep length and quality or stress levels. ‘In addition, the “morning larks” who consistently rise early enough for morning exercise may be biologically different from their “night owl” counterparts.’

Studies suggest people who get up earlier have circadian rhythms — or ‘body clocks’ — that run earlier, which could improve sleep quality and ensure a consistent schedule, which can all drive weight loss. Scientists found people who were early birds were 10 to 13 years older than those in the other two groups. Most of them also had a college degree and said they had never smoked or used alcohol. They also had healthier diets and ate less than those in the other two groups. For the study, published today in the journal Obesity, scientists looked at data from the official National Health and Nutrition Examination Survey (NHANES) — which assesses the health of about 5,000 adults and children in the US every year.

The data utilized in this study was collected between 2003 and 2006, during which participants wore fitness trackers, also known as accelerometers, on their hip for seven consecutive days to monitor their exercise routines. Although the National Health and Nutrition Examination Survey (NHANES) still employs fitness trackers, they are now worn on wrists, which renders comparisons with more recent years less dependable.

The study involved the use of data from the trackers to categorize participants into three groups based on their exercise routines: morning (7am to 9am), midday (11am to 1pm), and evening (5pm to 8pm). The scientists then analyzed the data on the participants’ body mass index (BMI) and waist circumference in each group to determine which group was least likely to be obese.

The results indicated that the morning group had the lowest BMI at 25.9 kg/m2, which is slightly above the healthy range of 18.5 to 24.9 kg/m2. The midday and evening groups had similar BMI values of 27.6 and 27.2 kg/m2, respectively, which are within the overweight range. Waist circumference was also lowest in the morning group at 36 inches (91.5 centimeters), while the evening and midday groups had waist circumferences of 37.4 inches (95cm) and 37.7 inches (95.8cm), respectively.

Dr. Tongyu Ma, an exercise physiologist at Franklin Pierce University in New Hampshire, commented that “our findings propose that the diurnal pattern of moderate to vigorous physical activity could be another important dimension to describe the complexity of human movement.”

Although researchers have varying opinions on the optimal time of day to exercise for weight loss, several studies suggest that morning exercise is the most effective. For instance, a 12-week study conducted on 100 adults from Skidmore College, New York, published last year, suggested that women interested in losing fat were better off exercising in the morning. Similarly, a paper from Sweden’s Karolinska Institute published earlier this year found that exercising in the morning was best for weight loss, as mice had a higher fat metabolism when exercising early in the day.