- The results of a new study released this week suggest that late-afternoon and nighttime exercise can be beneficial for glucose regulation.
- Exercises of moderate to high intensity were reported to decrease liver fat and insulin resistance.
- Researchers observed no correlation between morning and daytime activity and insulin resistance.
Recent studies have shown that working out in the late afternoon or evening can help regulate blood sugar levels more than any other time of day.
Results from the study showed that exercising between the hours of midday and midnight reduced insulin resistance more than exercise performed earlier in the day. The findings were published online on November 1 in the journal Diabetology.
According to Healthline, the study’s lead author, Jeroen van der Velde, PhD, of the Department of Clinical Epidemiology at Leiden University Medical Center, said, “Our aim was to investigate associations of timing of physical activity and breaks in sedentary time with liver fat content and insulin resistance in a middle-aged population.”
Men and women between the ages of 45 and 65 who were either overweight or obese (defined as a body mass index (BMI) of 27 or higher) were included in the analysis of data from the Netherlands Epidemiology of Obesity (NEO) study.
They recruited over 6,700 persons by inviting all residents of one Dutch municipality aged 45–65 with a body mass index (BMI) indicative of the broader population as a control group.
Blood samples were collected from all subjects during the physical examination to determine fasting glucose and insulin levels.
In addition to answering questions about their habits, some participants were randomly selected to undergo an MRI scan to assess the amount of fat in their livers.
To track their activity levels and heart rates for four days and nights, 955 people were selected at random and given a single device.
The study split the day into three segments, from 6 a.m. to 12 p.m., from 1 p.m. to 6 p.m., and from 6 p.m. to midnight, to see when time of day saw the highest levels of MVPA.
Researchers were able to estimate the time spent at different exercise intensities by using these observations to calculate the total energy expended during physical activity.
The final sample size was 775 participants who had all their information filled out.
Evening exercise reduced insulin resistance by 25%
Exercise in the afternoon was associated with an 18% reduction in insulin resistance, and exercise in the evening was associated with a 25% reduction, according to the study’s authors.
They also discovered that moderate to strenuous exercise helped decrease liver fat and insulin resistance.
On the other hand, van der Velde and colleagues showed no statistically significant distinction between morning activity and day-to-day exercise in terms of insulin resistance.
Large difference was surprising
van der Velde said he wasn’t surprised by the results, given that earlier research in individuals with diabetes found the most positive benefits on glucose control were when high-intensity exercise was undertaken in the afternoon rather than the morning.
But we looked at regular moderate-to-vigorous physical exercise in our study,” he said. High-intensity exercise is part of a healthy lifestyle, but brisk walking and cycling are more common.
There were still significant disparities in insulin resistance of up to 25% between those who were most active in the evening and those who were equally active throughout the day, as he and his team had previously documented.
A discrepancy of this magnitude surprised van der Velde.
What is insulin resistance?
As explained by Dr. Ricardo Correa, head of the Endocrinology, Diabetes, and Metabolism Fellowship Program at the University of Arizona College of Medicine, insulin resistance happens when cells stop reacting to insulin.
So, “whenever insulin comes,” the receptor triggers a sequence that allows glucose to enter the cell, as he explained.
When the receptor is destroyed, “it can’t initiate the cascade so glucose cannot come in,” he explained. And that, as the saying goes, will keep all the glucose outside the cell.
If glucose isn’t able to enter the cells, high blood sugar levels persist, and diabetes type 2 develops.
The danger of insulin resistance is higher for persons who are overweight or obese, Correa said.
Type 2 diabetes is characterised by insulin resistance, he explained.
Benefits of exercise timing beginning to be understood
“We are only just beginning to understand the potential health benefits of timing of physical activity,” van der Velde stated.
He stressed that he took a group-level approach to analysing insulin resistance variations.
“Therefore, in order to translate our findings into individual guidance, there are a number of factors we need to understand,” he went on.
He also raised the question of whether shifting daily activity later in the day or to the evening would have the desired effect of enhancing insulin sensitivity.
Furthermore, as van der Velde pointed out, “we do not know if everyone will benefit from modifying their time of activities.”
Those who “meet the description of a morning person” would, he speculated, reap greater rewards from exercising first thing in the morning. For the time being, I believe that we should wait for future investigations to translate our findings into clinical messages.
Why exercise helps insulin resistance
As Correa described it, exercise provides an alternative route that bypasses insulin signalling. He explained that since “the two ways that glucose can enter the cell are through the insulin receptor or through exercise,” it follows that exercise can aid in blood sugar control, which in turn can help enhance insulin sensitivity.
‘So whenever we conduct exercise, we enable entry of glucose into the cells because glucose offers energy in exercise, so that’s a way the body needs to receive energy,’ he stated.
Exercise at any time is beneficial
Than claim that one time of day is superior to another is “a little bit contentious,” as Correa puts it, “since exercise anytime of day is good.”
He noted that the sample size employed in the study was somewhat tiny.
He advised taking the information “with a grain of salt.” Since the patient’s availability is taken into account while making workout recommendations. We shouldn’t advise people to only work out in the afternoon because some of them are offered first thing in the morning.
The bottom line
Reducing insulin resistance in overweight or obese persons has been linked to exercising in the evening, according to recent studies.
However, this does not mean that the only time of day to exercise is in the evening, as exercise is helpful at any time of day, according to experts.
In addition, they note that it is still unclear whether or not everyone would reap the same benefits from exercising in the evening and that additional study is required to draw definitive conclusions.