This Is the Best Time of Day to Exercise If You Have Obesity, New Research Says

The study—published on April 10 in the journal Diabetes Care—included data from nearly 30,000 people with obesity, 10% of whom also had type 2 diabetes. The research team found that participants who got most of their aerobic exercise between 6 p.m. and midnight had the lowest risk of heart disease and premature death.

"While we need to do further research to establish causal links, this study suggests that the timing of physical activity could be an important part of the recommendations for future obesity and type 2 diabetes management, and preventive healthcare in general," study author Emmanuel Stamatakis, PhD, professor of physical activity, lifestyle, and population health at the University of Sydney, said in a press release.

Though working out at night could provide more health benefits for people with obesity and type 2 diabetes, experts emphasized that exercise is a good idea whenever you can fit it in.

"Yes, in a perfect world, maybe evening is best," Matthew Freeby, MD, endocrinologist and director of the Gonda Diabetes Center at UCLA Health, told Health. "But if we can't get it in the evening, there are still benefits even at other times of the day."

According to experts, here's how exercise timing can impact health outcomes for people with obesity and type 2 diabetes and what to know before switching up your exercise routine.

Other research has previously found a connection between evening exercise and added health benefits for people with type 2 diabetes. But the researchers behind this new report wanted to further explore this idea, specifically learning more about how the timing of a workout might affect people's health in the long term.

The team relied on data from 29,836 people enrolled in the U.K. Biobank database. They all had obesity, and about 3,000 also had type 2 diabetes. The average age of the participants was about 62 years, and about 53% were women.

For a week, participants continuously wore a wrist accelerometer so researchers could accurately track each person's moderate-to-vigorous physical activity (MVPA). This includes a range of movements that get a person's heart rate up, from gardening or brisk walking to cycling or running.

Using this data, the study authors looked at how often participants worked out and put them into three different categories based on whether they got most of their MVPA in the morning, afternoon, or evening.

After tracking participants' health for nearly eight years, researchers found that those who got most of their MVPA at night had the lowest risk of all-cause mortality, cardiovascular disease, and microvascular disease, a type of heart disease that affects the smaller, branched-off arteries.

These findings were reflected in the subset of participants who had both obesity and type 2 diabetes as well—in fact, evening exercise in this group was even more so associated with lower mortality and cardiovascular morbidity, the study authors said.

Though nighttime MVPA was associated with the greatest health benefits, working out at any time of day was still linked to a lower risk of these adverse events in comparison to no aerobic exercise at all.

The study was observational, meaning it may have been prone to bias, and it did not prove that working out at night causes lower chances of all-cause mortality, cardiovascular disease, or microvascular diseases.

Experts don't know why exactly working out at night was associated with these benefits. But the authors suggested that nighttime physical activity may lead to lower glucose levels in the morning, which may provide metabolic benefits.

The study authors said more research should be done to further uncover the relationship between nighttime exercise and reduced risk of mortality and heart disease, specifically whether the former can lead to the latter.

Should You to Change Your Workout Schedule?

Generally speaking, adults should get 150 minutes of MVPA throughout the week, in addition to two days of muscle strengthening exercise. This can break down to five 30-minute workouts, Freeby said.

So if someone with type 2 diabetes or obesity is able to get that exercise in between 6 p.m. and midnight, they may want to consider trying it.

However, that schedule may not be realistic for everyone—there are a myriad of reasons why someone may find it hard to exercise, said Emily Nosova, MD, assistant professor of endocrinology at Mount Sinai.

"I always tell [patients], 'I'm not expecting you to run marathons or even invest in a gym membership since that's expensive,'" she told Health.

Instead, smaller sessions of physical activity at any time of day can still be beneficial.

"The vast majority of my patients have sedentary jobs; that's the reality of our current culture and lifestyle," Nosova said. "If there's any way to get up once an hour and walk around or climb the stairs, then you should absolutely [do that]."

To that end, it's important not to make any blanket recommendations that might discourage people from getting in movement when they can, Freeby added. For people with obesity, it's not nighttime exercise or bust.

"Logistically speaking, everyone is busy," he said. "Exercise has benefits regardless of when you do it. If it's only going to happen in the morning? Go ahead. Lunchtime? Also great. It really does come down to the individual patient doing it when possible."

If someone is looking to fit more physical activity into their routine—whether at night or during the day—there are a few things to be mindful of as you plan your start, experts said.

"For someone who's out of practice, I would recommend starting with some amount of supervision, like a personal trainer or a friend who can help monitor vital signs like blood pressure and heart rate," Nosova said.

This is especially true for people with overweight, obesity, or type 2 diabetes, she added, since they may have other conditions, such as hypertension, that can be affected by exercise. People should always take a pause if they're noticing dizziness, heart palpitations, or simply don't feel like they can continue, said Freeby.

And it's also a good idea to talk to your healthcare providers when you're starting any new exercise routine so they can go over any specific warning signs to look out for, he said.