It’s the age-old debate: what time of day is best to exercise?
But now an intriguing new study appears to have answered that question.
Researchers in Spain found that those who exercised (running, cycling, or another activity) at 6 p.m. had lower blood sugar levels than those who exercised in the morning.
The scientists argued that this suggested that late exercisers both had a more active metabolism and were better able to resist hunger pangs.
This meant they would both burn more calories and expend less energy during the day, they suggested.
Researchers in Spain found that those who exercised (running, cycling or another activity) at 6 p.m. had lower blood sugar levels than sedentary people
Normally, muscle cells are less able to absorb blood sugar levels in the evening, research suggests – because insulin drops at this time.
But exercise in the evening increases insulin levels, making it easier for cells to absorb sugar from the bloodstream and burn it for energy.
For the study, researchers followed 186 Spanish adults in their 40s, most of whom were obese, for two weeks.
Each participant wore an accelerometer to track effort and a continuous blood glucose monitor to monitor blood sugar levels.
Training times were split into morning (6:00 AM to 12:00 PM), afternoon (12:00 PM to 6:00 PM) or evening (6:00 PM to 12:00 PM).
Researchers then compared the blood sugar levels of sedentary participants, who did not exercise for a day, with those who had exercised at the different times.
The map above shows the obesity rate by US state in the year 2022, the most recent data available. The data was revealed Thursday by the Centers for Disease Control and Prevention
The U.S. obesity rate is up compared to a decade ago, when no state had an obesity rate above 35 percent. The CDC says it is an “urgent priority” to address the nation’s growing waistline
Dr. Antonio Clavero-Jimeno, an exercise scientist at the University of Granada in Spain, and others wrote in the study: “(Exercise) in the evening appears to have a beneficial effect on (blood sugar levels) in sedentary adults with obesity.”
The study was only conducted in obese and overweight people, making it unclear whether the results also apply to people with a healthy weight.
But it follows in the footsteps of other studies that have suggested evening exercise is best for weight loss.
A study from the University of Sydney, Australia, found that obese people who exercised after 6 p.m. had an approximately 36 percent lower risk of heart disease.
Among those who exercised before then, the benefit was only half as high – or 17 percent less likely to develop the condition.
Another study from Germany, conducted in 2022, involving 5,000 overweight or obese people also found that those who exercised in the evening had a reduction in insulin resistance of up to 25 percent.
A handful of weight loss studies have suggested that exercising in the morning is best for weight loss.
These are based on data showing that those who exercise at this time tend to be thinner than those who exercise in the evening.
But these don’t take into account other factors, such as more health-conscious people starting their day earlier with a workout.
Any amount of exercise at any time of day can cause weight loss in obese people, as long as they don’t eat excess calories, doctors say.
The World Health Organization (WHO) says everyone should exercise at least 150 minutes every week.