A Large New Study Reveals the Ideal Two-Hour Workout Window for Weight Loss
Is there a best time of day to work out if you want to lose weight? It's something researchers have been trying to figure out for years, and a large new study points not just to a time of day, but a specific window of time: Between 7 and 9 a.m.
The study, which was published in the journal Obesity, monitored the exercise habits of over 5,000 participants. Researchers found that when the study participants exercised between the hours of 7 and 9 a.m., they were more likely to have a lower waist circumference and less likely to be obese than those who worked out midday or at night.
But why is this specific window so significant? Parade talked with doctors who specialize in weight loss. Here's what they had to say.
How To Think About the 7 to 9 AM Exercise Window
Both doctors are a bit stumped when it comes to that specific window of time, but Dr. Michael Glickman, MD, a double board-certified family medicine and obesity medicine physician, says exercising in the morning is known to have several advantages. "For many people, their appetite is naturally lowest in the morning which means they can exercise on an empty stomach," he says. "There is mounting evidence that exercising in a fasted state will cause a shift in fuel utilization that favors fat oxidation. This effect may be present for up to 24 hours after the workout—perhaps resulting in additional fat loss when compared to exercise in the fed state."
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Another benefit to morning exercise, he says, is that it may better align with our innate circadian rhythm. Cortisol, for example, is a stress hormone that is naturally highest in the morning and gradually declines throughout the day. "Since exercise itself is a form of acute stress, it triggers additional cortisol release. Given the link between chronically elevated cortisol and weight gain, perhaps afternoon or evening exercisers are at a slight disadvantage," Dr. Glickman says.
Furthermore, many people feel their best in the morning when their energy, alertness and motivation are at their peak, he adds. "Perhaps morning exercisers are able to engage in a higher quality workout than their peers who exercise later in the day after some physical and mental fatigue has set in."
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Dr. Mark Drucker, MD, a doctor with Beyond Slim who specializes in weight loss, adds that exercise has a thermogenic effect, meaning increases metabolism or basal metabolic rate (BMR) both during exercise and for a residual period after exercise. "Getting your exercise first thing in the morning gives you more hours following the exercise to take advantage of this residual thermogenic effect," he explains.
Some people have a metabolism that is a little slower to get going in the morning, he adds, and getting your exercise first thing in the morning will help get your sleep metabolism revved up. "It is also possible and likely that people wishing to lose weight who exercise first thing in the morning are more mindful at the beginning of the day of their weight loss goals," Dr. Drucker says. "This may help them eat more healthily both first thing in the morning and throughout the day."
Related: This Morning Habit Will Help You Lose Weight Faster
The Bottom Line
Is exercising in the morning going to help you lose weight? According to the results of this study, probably. But Dr. Drucker emphasizes that for those interested in weight loss, weight management or just getting and staying healthy, any time of day that works for you is a great time of day to exercise.
"For those of you particularly interested in weight loss and weight management consider getting your exercise first thing in the morning as this recent study showed there is a consistent advantage to getting your exercise early in the day," he says. "If it is convenient and works with your schedule to get your exercise early, then by all means, see if you can make that happen."
If it’s not convenient for you, though, don't stress. "You will still get plenty of benefits from exercise any time of day."
Next up: 15 Best Workouts for Weight Loss, According to Trainers
Sources
Dr. Michael Glickman, MD, double board-certified family medicine and obesity medicine physician
Dr. Mark Drucker, MD, a doctor with Beyond Slim
