Taking a walk after dinner can help manage blood sugar levels. Engaging in physical activity in the evening can be particularly beneficial for those with obesity, aiding in blood sugar regulation and offering protection for heart health.
Key Points to Note
- Evening physical activity significantly lowers the risk of heart disease and mortality in people with obesity, more so than morning or afternoon exercise.
- Engaging in exercise at any time of the day is better for reducing these risks than being inactive.
- Nighttime exercise may help regulate blood sugar levels due to lower insulin sensitivity during that time.
Performing the majority of moderate-to-vigorous physical activity in the evening has been associated with improved health outcomes for individuals with obesity, as suggested by an Australian study published on April 10 in Diabetes Care.
The study found that aerobic exercise sessions lasting at least three minutes and conducted primarily in the evening (between 6 p.m. and midnight) led to the most significant reductions in mortality and cardiovascular disease. Angelo Sabag, PhD, a lecturer in exercise physiology at the Sydney School of Health Sciences, highlighted that evening exercise showed the most pronounced benefits in reducing death rates and heart disease.
“But the key message from our study is that physical activity at any time is associated with a reduced risk of cardiovascular disease and mortality in adults with obesity,” he said. Overall, these findings highlight the importance of physical activity for heart health and mortality, says Dr. Sabag.
Morning, Afternoon and Evening Exercisers Monitored for 8 Years
To investigate the relationship between exercise timing and the risk of heart disease and death from any cause, researchers analyzed data from nearly 30,000 adults with obesity aged 40 and older, drawn from the UK Biobank. The average age of participants was 62, and about 10 percent (2,995 individuals) had been diagnosed with type 2 diabetes. Participants with preexisting heart disease, cancer, or both were excluded from the study.
Participants’ physical activity levels and timing were tracked using accelerometers worn 24 hours a day for a week at the study’s outset. This device captured all forms of movement, including routine activities like walking during the workday or household chores, as well as structured exercises such as running or walking.
Based on the timing of their moderate to vigorous physical activity, participants were categorized into three groups: morning, afternoon, or evening. Moderate activities included brisk walking, dancing, and gardening, while vigorous activities encompassed jogging, running, fast cycling, fast swimming, and walking briskly up a hill.
The researchers then linked this activity data with health information from the National Health Services and National Records of Scotland, tracking participants’ health over an average follow-up period of 7.9 years. During this time, there were 1,425 deaths, 3,980 cardiovascular events, and 2,162 instances of microvascular dysfunction, such as decreased nerve, kidney, or eye function (neuropathy, nephropathy, or retinopathy).
To isolate the impact of exercise timing on health outcomes, the researchers controlled for various factors, including demographics, smoking, alcohol consumption, diet, and sleep patterns.
Those Who Exercised in the Evening Showed Lowered Risk of Death
When participants were compared to a control group with no bouts of moderate to vigorous physical activity, researchers uncovered several key findings:
- Individuals who performed most of their aerobic physical activity between 6 p.m. and midnight exhibited the lowest risk of premature death and death from heart disease.
- Evening activity was associated with a 61 percent lower risk of dying from any cause, whereas afternoon activity was linked to a 40 percent lower risk, and morning activity to a 33 percent lower risk.
- For heart disease mortality, evening activity correlated with a 36 percent lower risk, afternoon activity with a 16 percent lower risk, and morning activity with a 17 percent lower risk.
- Evening exercise was also linked to a reduced risk of microvascular complications, such as neuropathy, nephropathy, and retinopathy, with risks decreasing by 24 percent for evening activity, 16 percent for afternoon activity, and 21 percent for morning activity.
- Additionally, the frequency of evening physical activity appeared to be more crucial than the total amount of daily physical activity.
These findings highlight the significant benefits of evening exercise, particularly in reducing mortality and improving cardiovascular and microvascular health outcomes among individuals with obesity.
While further research is necessary to establish a causal link between the timing of physical activity and decreased health risks, this study suggests that the timing of exercise could play a crucial role in future recommendations for managing obesity and type 2 diabetes, as well as in preventive healthcare overall, says Sabag.
Exercising Later May Compensate for Lowered Sensitivity to Insulin
Matthew Kampert, DO, a physician specializing in sports medicine and endocrinology, and the director of exercise medicine at the Endocrinology and Metabolism Institute at Cleveland Clinic in Ohio, explains that these findings align well with prior research. Previous studies have demonstrated that insulin sensitivity follows a circadian rhythm, suggesting that the body’s response to insulin varies at different times of the day.
“Some believe that this decreased insulin sensitivity during evening hours was developed to protect against hypoglycemia (low blood sugar) throughout the night, when people would typically not consume food,” said Dr. Kampert, who was not involved in the study.
According to Sabag, individuals who cannot produce additional insulin to compensate, such as many people living with obesity included in the study, may find that engaging in physical activity later in the day helps mitigate some of the insulin resistance that typically occurs in the evening.
Exercise lowers blood sugar through two primary mechanisms:
- Physical activity enhances insulin sensitivity, enabling muscle cells to effectively utilize insulin to absorb glucose (sugar) both during and after exercise.
- Muscle contractions during exercise allow cells to uptake glucose and convert it into energy independently of insulin availability.
“While this interpretation provides some insight into potential mechanisms, further research is required to gain a more comprehensive understanding of such processes,” said Sabag.
Could Some of the Benefits Be Caused by What People Weren’t Doing at Night?
Evidence suggests that late-night eating and snacking often involve more processed foods. Could part of the risk reduction be attributed to the types of foods that evening exercisers are avoiding?
Although the study was designed to have control for many factors, it is much more challenging to control for dietary factors, Sabag explained. Researchers had to depend on self-reported food recall and diaries from the diet of the participants. “Nonetheless, we controlled for fruit and vegetable consumption and diet quality index, and the results remained consistent,” he said.
Should You Start Exercising in the Evening?
This study managed to establish only an association, not causation, Kampert stressed. “It is most important to meet recommended guidelines for exercise first, before worrying about what time of day is ideal,” he said.
The guidelines for physical activity recommend engaging in 150 minutes of moderate-intensity exercise per week, along with two days of muscle-strengthening activities such as resistance training or weightlifting.
“Despite all the existing knowledge around the health benefits of exercise, only 1 in 4 adults are meeting current physical activity recommendations,” said Kampert.
Sabag agrees, as this study shows that physical activity at any time of day helped better the final output compared to those who weren’t engaging in any physical activity. “Health professionals and guidelines should encourage individuals to incorporate or structure their physical activity into a routine that is sustainable in the long term in order to yield greatest health improvements,” he said.
According to him, individuals with flexible schedules and metabolic conditions like obesity, metabolic syndrome, or diabetes may benefit from scheduling physical activity in the evening. This timing could potentially improve glucose regulation and lower the risks of cardiovascular and overall mortality.
Does Exercising in the Evening Interfere With Sleep?
“Some reports show that exercise, particularly of high intensity, may interfere with sleep duration and quality, however the jury is still out,” Sabag stated.
Traditionally, it was advised to avoid exercising a few hours before bedtime. However, recent research indicates that evening physical activity does not disrupt sleep. A meta-analysis of 23 studies further confirmed that late-day exercise generally does not lead to sleep disturbances, although it is advisable to avoid vigorous exercise within one hour of bedtime.
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