A New Study Found That This Is the Best Time of Day to Exercise if You Want To Burn Fat

Plus, the workout that will burn the most fat in that time frame.

When it comes to boosting metabolism and burning fat, does the time of day you exercise matter? Yes, as it turns out: According to a new study, late-morning exercise may be more effective.

For the study, researchers examined mice that exercised in an early active phase (equivalent to morning exercise in humans) and early rest phase (equivalent to evening exercise in humans). They found the early active group had a greater increase in metabolism compared to the early rest group.

While experts can't explain exactly why this is, they have some strong theories. Here's why exercising in the late morning can be so effective for burning fat.

Why Late Morning Exercise Burns More Fat

Increased energy

When you work out in the morning, your body's energy reserve is still intact and you have enough energy to exercise at maximum effort and get the most out of your workout.

This helps you burn more calories in the process and lose more fat, John Gardner, a NASM-certified personal trainer and the CEO and cofounder behind Kickoff, explains. Not only that, but you can also challenge yourself to lift heavier weights, do more reps and really push yourself to get better results, helping you burn more calories and build more muscle.

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Higher cortisol levels

Another huge advantage is that the body has a higher level of cortisol and growth hormone in the morning which aids in boosting metabolism.

When working out in the morning, you use your energy from fat reserves as your carb reserves are almost used up, which helps reduce fat and aid in weight loss, especially when exercising on an empty stomach and using fasted cardio. In fact, this can burn up to 20 percent more body fat, Gardner states.

Encourages the development of healthier habits

Working out in the morning can help someone create better habits and requires enhanced planning to create that habit, Michael Hamlin, NSCA, CSCS, explains. By working out in the morning when we're fresh, there's a better chance that an exercise habit can be formed, which will allow us to burn more body fat over longer periods of time.

Exercises To Boost Metabolism and Burn Fat

Now you know what time to exercise to burn fat, but which exercises work best? One of the best high-impact workouts to burn calories even after you've exercised is high-intensity interval training (HIIT).

“When it comes to HIIT workouts, my go-to is usually a Tabata workout which follows a four-minute workout of 20 seconds on-10 seconds off for 8 rounds,” says Gardner. “During these 20 seconds, a person gives their maximum effort and rests for 10 seconds, which really helps spike the heart rate. You can do 4 or 5 sets of Tabata workouts, get your heartbeat pumping and really break a sweat.”

The best thing about this workout is that it is intense, and effective and boosts metabolism and fat burning for up to 48 hours post-workout. This is a great way to not only boost endurance and overall fitness levels, but to continue burning calories and fats even after your workout, Gardner adds.

To get the most out of each workout, Gardner suggests the following:

  • Make sure you're reaching at least 80 percent of your maximum heart rate during interval training.

  • Limit rest periods between sets to keep your heart rate up. It is best to rest for 30-60 seconds before you get your heart rate pumping again.

  • Use compound exercises

  • Continue to challenge yourself

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In terms of the last tip, Gardner emphasizes the importance of not getting "used" to any exercise. “You need to constantly switch it up, challenge yourself and increase weights or variations to your workouts that require more physical strength. This can be by adding weights, using more muscle groups, or adding more resistance," he says.

Next up: The Actual Exercise Is Only Part of the Equation—Here's What to Eat for Your Strongest Workout Ever