Working Out Later in the Day May Better Help Control Blood Sugar

• Getting exercise in during the afternoon or evening hours may help control blood sugar levels, according to new research.
• People who are afternoon or evening exercisers had reduced insulin resistance, compared to people who get other physical activity throughout the day.
• Morning exercise routines did not have an effect on insulin resistance.

Working out in the afternoon or evening may help decrease insulin resistance—and in turn, control blood sugar levels—compared to getting other movement throughout the day, new research shows.

The study, published last week in the journal Diabetologia, set out to further explore the connection between physical activity and metabolic health—specifically the timing of that physical activity and breaks taken during sedentary behavior.

“The timing of different things that we do with our day, like eating or exercise, are starting to be recognized as important factors in our overall health,” Katie Page, MD, one of the directors of the diabetes and obesity research institute at Keck Medicine of the University of Southern California, who was not involved in the new research, told Health. “It’s not just the time that we eat, but it’s the time that we exercise and when we’re physically active that can also play a role.”

What To Do When Your Blood Sugar Is High

Decreased Insulin Resistance and Evening Exercise

For the study, researchers from the Netherlands used data from the Netherlands Epidemiology of Obesity (NEO) study, which was designed to investigate obesity-related diseases. All invited participants—recruited between 2008 and 2012—lived in the Netherlands, and were men and women between the ages of 45 and 65 years old.

More than 6,600 participants were invited to participate in the study. Some had a self-reported Body-Mass Index (BMI) of 27 kg/m² or higher, a range which includes people who are overweight or have obesity; others had a range of BMIs to represent the general Netherlands population.

Participants underwent a physical exams, blood draws, questionnaires, and MRI scans; some were also given an accelerometer and heart rate monitor to track activity levels.

A total of 775 participants had complete data sets for researchers to analyze. The final group was made up of 42% men and 58% women with an average age of 56 and a BMI of 26.2 kg/m².

After adjusting for variables (age, sex, ethnicity), researchers found an association between insulin resistance and the timing of a person's moderate-to-vigorous physical activity (MVPA). For those who got most of their activity in during the afternoon and evening hours (from 12 p.m. to 12 a.m., or between noon and midnight), insulin resistance was reduced by 18% and 25%, respectively, compared to getting even amounts of exercise or movement throughout the day.

Exercising during the morning hours, however, did not to have any effect on insulin resistance.

The total amount of a person's physical activity energy expenditure (PAEE)—and specifically their MVPA—also had an effect on their liver fat content and insulin resistance. People who got more movement overall, regardless of how much time they spent sedentary or how many sedentary breaks they took, had reduced liver fat content and reduced insulin resistance.

Though previous studies had shown that afternoon and evening exercise was beneficial for those with type 2 diabetes, the extent to which evening exercise specifically was beneficial surprised researchers.

“We still observed differences up to 25% in insulin resistance between those mostly active in the evening [versus] the group of participants with an even distribution of [MVPA] throughout the day,” lead study author Jeroen van der Velde, PhD, a postdoctoral researcher at Leiden University Medical Center, told Health in a statement.

Importance of Keeping Insulin Resistance Low

Insulin is a hormone made by the pancreas. It helps glucose, or blood sugar, enter the cells in your body, where it's used for energy. Insulin resistance, then, happens when the cells in your body don't respond well to insulin and can't easily take in glucose.

If insulin resistance stays high, the pancreas has to work overtime to make more insulin to help glucose to enter the body’s cells. This can increase the risk for prediabetes or type 2 diabetes, conditions in which the body has higher-than-normal blood sugar levels.

Physical activity, however, allows the body to better use blood sugar, and can play a role in reducing insulin resistance.

“The glucose that's usually circulating in the bloodstream moves into the muscle and gets used up by the muscle when you're exercising, so it actually improves the efficiency of the insulin and allows the glucose to enter into the muscle where it's used as an energy source,” said Dr. Page. “[It] improves the ability of insulin to do its job.” 

How 2 Minutes of Walking After a Meal Can Help Control Blood Sugar Levels

Not Enough Evidence to Recommend Specific Workout Times

Though study findings suggest that people who are insulin resistant may benefit from afternoon or evening workouts, researchers say that it's still too early to know if the results can be generalized to other age groups and countries.

"Our results should be generalizable to the general Dutch middle-aged population that is at risk for type 2 diabetes," said van der Velde.

The study was also on the smaller side, with data from less than 1,000 people, and involved the researchers just observing participants.

“This was an observational study—basically, they just were watching with these accelerometers how much people were exercising. But it wasn't a randomized control trial, which is what you would need to actually prove a causal role,” said Dr. Page. “But I think it really highlights the importance of looking at this further.”

Still, for those who do share some similarities with those participants in the trial, it’s very possible that exercising in the afternoons and evenings could have a positive effect on blood sugar levels. Previous research has also shown that getting a small amount of movement after eating a meal—even as little two minutes—can also help control blood sugar levels.

According to van der Velde, similar meal times in the US and the Netherlands may also lend to similar outcomes. Many people in the Netherlands eat their largest meal of the day in the evening—similar to people in the US typically eating large dinners. Those larger evening meals may somehow be connected to the study results, van der Velde told Health.  

Any Exercise at Any Time Is Beneficial

Researchers and other experts agree that the timing of exercise is less important than getting extra movement in general. That means, according to van der Velde, that morning people likely don't need to completely revamp their routines.

"Maybe people that can be characterized as [morning people] actually will benefit more from physical activity earlier in the day," said van der Velde. "If the morning is the only time of the day it is possible [to exercise], definitely do so."

The type of exercise—though any kind is beneficial as long as you enjoy it—may be less complicated than you may think.

“[MVPA] does include high intensity exercise, but is mostly comprised of brisk walking and cycling (the latter especially in the Netherlands),” said van der Velde.

The main takeaway: While some people may benefit from evening workouts, it's difficult to know whether everyone will. In that case, people getting exercise in the way that's accessible to them is most important.

“Incorporating exercise whenever it works for that person’s schedule is the key,” said Dr. Page. “It may be more effective at certain time points for certain people, but I think trying to just work with your own schedule is probably, in an individual case, the most important thing.”