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Researchers say morning exercise may be most effective for weight loss, but consistency at any time of day is key. Thomas Barwick/Getty Images
  • Researchers say exercising between 7–9 a.m. is best for weight management.
  • Morning exercisers had a lower body mass index and waist circumference than those exercising later.
  • Experts say better sleep, mental health, brain health, and physiological health are also important benefits of exercise.

The early bird exercising in the morning is best at catching the weight management worm, according to a new study.

Researchers report that even though epidemiological evidence has been controversial over the optimal timing of physical activity for weight management, their findings suggest that exercising between 7–9 a.m. appears to be the best time of day to garner health benefits.

The researchers said that moving during those hours best enhances the association between daily moderate to vigorous physical activity and obesity prevention.

The study was published today in the journal Obesity.

“Our study provided a novel tool to explore the diurnal pattern of physical activity and to investigate its impact on health outcomes,” said study author Dr.Tongyu Ma, a research assistant professor in the Health Sciences Department of Franklin Pierce University in New Hampshire and the Department of Rehabilitation Sciences at the Hong Kong Polytechnic University in China.

The researchers said previous research has focused on the frequency, intensity, and duration of physical activity, but few studies focused on the diurnal (daytime) pattern of accelerometer-measured physical activity to classify the time of day of human movement.

The researchers noted it’s unclear whether accumulating physical activity at different times of day is equally associated with obesity prevention.

They also said it’s unclear whether meeting the World Health Organization’s (WHO) physical activity guidelines of 150 minutes a week of moderate to vigorous physical activity, with different patterns, is equally beneficial for reducing obesity risk.

The researchers explored whether the diurnal pattern of accelerometer-measured moderate to vigorous physical activity influences the relationship between such human movement and obesity.

The team used data from the 2003–2004 and 2005–2006 cycles of the National Health and Nutrition Examination Survey by the Centers for Disease Control and Prevention (CDC) because accelerometry (the measure of acceleration) was implemented during that time.

The cycles analyzed 5,285 participants, looking at moderate to vigorous physical activity in the morning, midday, and evening with an established algorithm that identifies hidden patterns in unlabeled data sets.

Researchers said the results showed a strong linear association between moderate to vigorous physical activity and obesity prevention in the morning group, whereas a weaker connection was found in the midday and evening groups.

Participants meeting the physical activity guidelines in the morning cluster had a lower body mass index and waist circumference than those in the other clusters.

Self-reported dietary recall also showed morning participants had a healthier diet and less daily energy intake per unit of body weight compared with other clusters.

In addition, the study authors reported morning participants spent a significantly higher amount of time of sedentary behavior than the participants in the other clusters. Despite the longer duration of sedentary time, the lower body mass index and waist circumference outcomes in the morning group remained.

Morning cluster participants were also 10 to 14 years older than people in the two other groups. In addition, the morning cluster had the highest percentage of female participants among the three groups.

Most participants in the morning group were primarily non-Hispanic white, had a college or higher education, and had never used tobacco or alcohol.

“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,” the study authors wrote.

Experts told Medical News Today that the study was promising, but that exercise at any time of the day is still preferred over none at all.

“The association of exercise early in the day and boosting the metabolism has previously been studied, but not as much as the effect on obesity,” said Dr. Mir Ali, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in California, who was not involved in the study.

“I don’t think there is enough data to make a permanent change in recommendations; however, telling patients that early in the day exercise seems to be better for weight loss is reasonable,” Dr. Ali told MNT. “There are many factors that will change the effectiveness of exercise, no matter what time it is done. Age, weight, sleep, and work cycle, etc., are all factors.”

“The important thing with exercise is consistency. The type of exercise does not seem to be as important as being able to consistently perform 150 minutes a week. I recommend to my patients that getting 30 minutes per day of exercise, even walking, at least five days a week is a good goal.

— Dr. Mir Ali, bariatric surgeon

Ali noted that for people trying to lose weight, exercise is important, but weight loss is primarily affected by diet. Changing to a healthier diet is the most important factor in trying to lose weight.

Ryan Glatt, a certified personal trainer, senior brain health coach and director of the FitBrain Program at Pacific Neuroscience Institute in California, said the study is “interesting” but doesn’t cover everything contributing to weight loss.

“There may be other factors that contribute to weight management, such as age, gender, race, and even location,” Glatt told MNT.

“Diet also plays a role and future studies should consider measuring these sociodemographics and other factors to see how they relate to outcomes such as weight loss,” he added.

Glatt added that if morning exercise doesn’t work for some people, that doesn’t mean it can’t work later.

“The recommendations of exercising at least 150 minutes per week at a moderate intensity or greater do not specify time because there is not yet enough research to determine an optimal time to exercise for weight loss,” Glatt said.

There are other benefits as well to exercising any time.

“Even if an optimal time was determined for different populations, weight loss is only one of the many benefits derived from exercise. Better sleep, mental health, brain health, and physiological health are also important benefits of exercise, and time of day may be less important than actual exercise participation.”

— Ryan Glatt, personal trainer

When it comes to exercise, people should find an activity they enjoy, said Dr.Kevin Huffman, a doctor of osteopathic medicine, a licensed fitness specialist, and chief executive officer of On the Rocks Climbing Gym in Elyria, Ohio.

“What truly matters is finding a workout routine that suits your individual lifestyle­ and preference­s,” Dr. Huffman told MNT. “The most effective­ exercise re­gimen is the one you can consistently stick with.”

Huffman added that although morning exercise helps e­stablish a healthy routine and increasing mood and e­nergy levels throughout the­ day, it’s important to know that evening or afternoon workouts can be­ equally effective­ for managing weight.

“The crucial factor is prioritizing regular physical activity and combining it with a balance­d diet to achieve your weight management goals,” Dr. Huffman said.

“Ultimately, the­ ideal time to exe­rcise is wheneve­r it fits into your daily schedule and allows you to maintain a long-term commitme­nt to your health and fitness journey.”