It’s the age-old debate: what time of day is best to exercise? Should you go to the gym in the early hours of the morning when you are half asleep or after a long day at work when you are exhausted?
An intriguing new study seems to have settled the question.
Researchers from the University of Sydney have shown that people who exercise at night have a lower risk of developing heart disease and death than those who exercise in the morning.
The study found that obese people who exercised after 6 p.m. had a 61% lower risk of death and a 36% lower risk of developing heart disease than obese people who did not exercise at all.
But obese people who exercised in the morning got about half the benefit—they were only 33 percent less likely to die and 17 percent less likely to develop heart disease.
Evening exercise won out as the most effective method for longevity in this study
“Exercise is by no means the only solution to the obesity crisis, but this research suggests that people who can schedule their activity around certain times of the day may be best able to offset some of these health risks,” the author of study Dr Matthew Ahmadi from the University of Sydney said.
Researchers from the University of Sydney analyzed the exercise and outcomes of nearly 30,000 obese people with an average age of 62 over eight years. At the beginning of the study, they tracked the individual’s physical activity for a week using a 24-hour fitness tracker.
Their physical activity was not limited to exercise, but also included things like walking and cleaning the house.
Participants were sorted into four categories based on when their main activity occurred: morning, afternoon, and evening. Morning athletes trained from 6 am to noon. Afternoon athletes trained from noon to 6 p.m. Evening athletes trained from 6 pm to midnight.
After eight years, the scientists analyzed the data, making sure to account for differences in age, gender, smoking habits and food intake. They also excluded individuals with pre-existing heart disease and cancer.
The researchers used an accelerometer, which is like a Fitbit, to determine the participants’ activity level
Evening exercisers had the best results compared to the other groups. Afternoon exercise was also found to be less effective than evening exercise, with a 40 percent lower risk of death and a 16 percent lower risk of developing cardiovascular disease.
“This study suggests that physical activity time may be an important part of recommendations for future management of obesity and type 2 diabetes and preventive health care in general,” Professor Emmanuel Stamatakis, study author and director of the Mackenzie Wearables Research Center at Charles The Perkins Center said.
The study authors provide several theories as to why this might be the case.
First, blood sugar levels are often higher at the end of the day. If you exercise when your blood sugar is relatively high, your muscles can pull the excess sugar from your bloodstream and use it as fuel, giving you more energy and helping to increase your calorie burn.
This, over time, can help you maintain more weight and have better health outcomes.
The graph above shows estimates of the global incidence of diabetes.
Next, there is some evidence that exercising at night can help lower blood pressure at night, which can reduce the risk of heart disease.
Previous research by Japanese and Dutch researchers found that exercising in the afternoon and evening can better stabilize blood sugar and reduce the risk of insulin sensitivity; precursor to diabetes.
Meanwhile, other studies show that exercising in the evening can have a stress-relieving effect and reduce emotional eating behaviors.
In 2022, the WHO estimated that there are 890 million adults living with obesity.
Being overweight is linked to numerous lifestyle diseases such as heart disease, diabetes, cancer and more. There were 537 million adults living with diabetes in 2021, according to the International Diabetes Federation.
Eating habits, genetics, and medical conditions can all contribute to someone’s likelihood of developing obesity. But doctors routinely recommend regular exercise as one of the best ways to fight obesity.
