Morning workouts might be better for weight loss, study finds

Is morning the best time of day to exercise? Research published Tuesday in the journal Obesity finds that early morning activity – between 7 a.m. and 9 a.m. – could help with weight loss.

“My cautious suggestion from this study is that if we choose to exercise early in the morning, before eating, we can potentially lose more weight than exercising at other times of the day.” , said lead researcher Tongyu Ma, research assistant professor. at the Hong Kong Polytechnic University.

Ma and his team used two years of data from the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey, which included the exercise, diet and lifestyle habits of more than 5 200 adults aged at least 20 years old. People in the study wore accelerators to measure their activity levels.

The data showed that people who exercised moderately to vigorously in the morning had a lower body mass index than people who exercised at midday or in the evening, although Ma said this could be due to a number of factors other than the timing of exercise.

On average, people who did moderate to vigorous exercise in the morning were more than ten years older than those who exercised later in the day.

Even if some young adults exercised in the morning, older age could explain these results, Ma said. The observed benefits “may not be due to activity habits, but rather to their age and to their different response to exercise.

Other factors besides the timing of exercise may also play a role: people who exercised in the morning were predominantly white and female, had a college degree, and had never used tobacco or tobacco. alcohol. They were also more likely to work out at the same time each day. Compared to those who exercised later, people who did so in the morning consumed fewer calories and, interestingly, spent more time sedentary than people in the other groups.

Ma cautioned that only a clinical trial, which the new study did not, can truly determine whether morning exercise is best. In a clinical trial, researchers could assign people of the same age and with the same lifestyle and eating habits a time of day to exercise, then directly compare the results.

“The results are interesting for science, but are not safe enough to be used to recommend morning exercise for optimal health,” said Cameron Mitchell, assistant professor of kinesiology at the University of British Columbia in Vancouver, in Canada, which did not participate. with the new research.

Ross Andersen, a professor of exercise physiology, medicine and nutrition at McGill University in Montreal, who was also not involved in the study, said it was difficult to attribute the observed benefits only for exercise. People who exercised in the morning probably also practiced a number of other healthy behaviors that contributed to their lower weight and better health, he said.

Why morning might be best

Over the past decade, numerous studies have explored what time of day people should aim to exercise to reap the greatest benefit — and the latest study likely won’t have the last word.

But there are several reasons in favor of exercising in the morning.

Andersen said he always encourages his patients to train early. While there are some physiological reasons why scientists think this might be beneficial, there is also a logical reason.

“It’s easy to put off self-care and say, ‘I’m just going to skip my exercise today because I’m too busy and something needs to be cut,'” he said. But if exercise is the first thing a person does in the morning, they may be more likely to do it every day, he added.

The body’s molecular clock may also explain why morning exercise might help with weight loss. In every cell of the body, especially in muscle, there is a molecular clock that triggers certain bodily functions, including those related to how fat is metabolized in the body, at different times of the day, Mitchell said.

Some early evidence has shown that exercise can reset this clock, returning it to its normal rhythms, which could be beneficial for metabolic health. But it’s not yet clear whether exercising at certain times of the day would have a greater impact.

Another possible explanation is that exercising in the morning, especially before eating, can also help the body burn fat.

Since people fast when they sleep, exercising before breakfast can help the body burn fat instead of carbohydrates, Ma explained. The benefits of exercise also last for hours after breakfast. end of training.

“Our metabolism not only returns to baseline after an intense workout, it stays a little higher. If people are walking most of the day with a higher metabolic rate, that’s a good thing,” Anderson said.

For those who train early, experts say, that’s not the only change they need to make if weight loss is the goal. A healthy diet is essential.

“It’s a holistic lifestyle approach,” Mitchell said, adding that exercise is a key part of the approach, especially since it helps people maintain muscle mass while losing weight. the fat.

If morning exercise doesn’t fit into a person’s schedule, Andersen said not to worry.

“The best time of day for people to exercise is when they enjoy doing it,” he said. “I wouldn’t dictate that people exercise in the morning if they really don’t like exercising in the morning, but if they are indifferent, I would recommend morning for them to do it.”Follow BNC HEALTH on Twitter & Facebook.