Diet & Exercise

This 2-hour window is the best time of day to work out for weight loss, study finds

If you have a choice, certain parts of the day offer different benefits when it comes to exercise.

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Sporty woman getting ready to work out.

If you're new to working out, you may be trying to figure out the best time to exercise so it works for your schedule and so you get the most health benefits. The truth is the best time to work out is whenever you're most likely to actually do it.

That said, research does show that certain times of day may offer health benefits over others.

The best time of day to workout

When TODAY.com interviewed several experts on the subject, they all pretty much agreed: Exercising in the morning is the best time of day to work out for logistical, effectiveness and health reasons.

A recent studied published in the journal Obesity found that exercising between 7 a.m. and 9 a.m. could help with weight loss. Based on data from 5,200 people 20 years old and over, researchers found that moderate to rigorous exercise in the morning was associated with a lower body mass index than exercising midday or in the afternoon.

That said, a few factors could be playing a role in the findings. For example, morning exercisers were more likely to have never consumed tobacco or alcohol, to consistently work out at the same time every day and to consume fewer calories, than midday or afternoon exercisers.

Lead researcher Tongyu Ma, research assistant professor at The Hong Kong Polytechnic University, told NBC News that his "cautious suggestion" from the study is that exercising early in the morning before eating can lead to more weight loss than exercising in other times of day.

But Cameron Mitchell, Ph.D., assistant professor of kinesiology at The University of British Columbia in Vancouver, Canada, who was not involved with the new research, told NBC News that he could not conclude working out in the morning leads to "optimal health" based on the study results.

Ross Andersen, Ph.D., professor of exercise physiology, medicine and nutrition at McGill University in Montreal, who was also not involved in the study, told NBC News he agreed, adding that people who exercise in the morning probably also practice other behaviors that help lower their weight and boost their health.

In fact, a study published in February 2023 found midday and afternoon exercise was linked with a lower risk of premature death, particularly for certain people.

The benefits of morning exercise

It pays to be a morning type: People who naturally woke up earlier in the day managed to squeeze in about 30 minutes more of physical activity a day for men and about 20 minutes more for women, compared to night owls, researchers in Finland found.

Women who exercised between 6 a.m. and 8 a.m. had greater reductions in their belly fat and blood pressure, and they achieved stronger leg muscles, compared to those who worked out in the early evening, researchers reported in 2022 in Frontiers in Physiology.

The exact mechanisms “remain elusive,” the authors wrote, but “morning exercise is increasingly recognized to benefit exercise adherence and weight management in overweight (and) obese individuals.”

Mitchell also said that early research shows that exercising in the morning could prompt the body's molecular clock, which controls when certain molecules perform certain functions, to reset itself, boosting metabolic health and weight loss.

Then, there’s the practical side: If you exercise in the morning, you get it over with right away, and there’s less chance of something interfering with your workout — like a last-minute project that forces you to stay late at work — and you have a momentum, Daniel Pink, author of “When: The Scientific Secrets of Perfect Timing,” previously told TODAY.com. Those early sessions can help you lose weight, form a habit or start the day with a mood boost, he added.

People who exercise in the morning feel very good about accomplishing that first thing, Jack Raglin, Ph.D., exercise psychologist and professor at Indiana University School of Public Health-Bloomington, previously told TODAY.com.

“You’ve gotten it out of the way and you’ve got the whole day ahead of you and you can check that off your list,” Raglin noted. Even if it’s tough to pull yourself out bed, you may be pleasantly surprised how good you feel once it’s done.

There’s also the positive impact a morning workout can have on your body. It releases endorphins, which help you feel great.

You may even want to consider exercising before breakfast: People who worked out on an empty stomach after fasting overnight burned double the amount of fat compared to those who exercised after eating the first meal of the day, a 2019 study found.

They were also able to better control their blood-sugar levels and adjusted easily to their before-breakfast workout sessions.

Such workouts on an empty stomach are not for everyone, including those with diabetes who are on insulin treatment and could increase their risk of hypoglycemia, Javier Gonzalez, Ph.D., study co-author and a senior lecturer in the department for health at the University of Bath, previously told TODAY.com.

Healthy people who are simply worried they won’t have the energy to get their heart pumping before their morning bagel can try drinking some strong black coffee before their workout to help the exercise feel a little easier, he advised.

The case for afternoon exercise

Exercise during the midday and afternoon — defined as the hours between 11 a.m. and 5 p.m. — was linked with a lower disk of premature death from all causes and heart disease compared to working out mostly in the morning or evening, researchers reported in Nature Communications in February 2023.

These benefits were particularly seen among older adults, men, people who were less physically active or those with pre-existing heart disease.

The exact reasons are a mystery, but the authors offered some possible explanations.

It may be due to how the body responds to activity based on its internal clock or circadian rhythm, including faster recovery of systolic blood pressure after exercise in the late afternoon than in the early morning.

Or perhaps eating and light exposure during the day boosted the benefits of afternoon workouts.

Another possibility is that afternoon exercisers engaged in a more comprehensive workouts that included both cardio and weights than their morning or evening counterparts, leading to greater health benefits.

The study shows the timing of moderate-to-vigorous intensity physical activity could "maximize the health benefits" of daily exercise, the authors wrote.

The findings were based on data from more than 92,000 people who wore an activity tracker and signed up to be part of the UK Biobank, a database with health information from half a million adults living in the U.K.

There are benefits to evening workouts, too

If you still prefer workouts later in the day, they can have their own unique benefits, too. Evening exercise — between 6:30 p.m. and 8:30 p.m. — “greatly” increased upper body muscle strength, power and endurance, and enhanced overall mood for women, according to the study published in Frontiers in Physiology. For men, the p.m. workouts lowered systolic blood pressure and fatigue, and stimulated fat oxidation compared to early morning exercise.

If you want to enjoy your workout more and find it less of a struggle, the late afternoon or early evening may be better. You’re warmed up, leading to a better performance.

“I tend to feel pretty creaky in the morning, but later in the day, I don’t feel creaky at all,” Pink said.

Plus, you can get the stresses of the working hours out and make the exercise session a ritual to end your day beneficially, Raglin noted.

This story first appeared on TODAY.com. More from TODAY:

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