Jamie Scheider
Assistant Editor

But what about how the timing of exercise affects our health? Can it really make that much of a difference whether you’re an early riser or a night owl at the gym? Luckily, a new study from the Journal of Clinical Endocrinology and Metabolism may have an answer. 

During this study, researchers analyzed whether working out before eating breakfast had any effect on health, specifically how fat becomes stored in muscles. This six-week experiment included 30 men who identify as obese or overweight and were split into three groups: a group who ate breakfast before working out, a group who ate breakfast after working out, and a control group who made no changes to their daily eating or exercise habits. What they found was that the group of men who worked out before breakfast burned double the amount of fat as the group who exercised after breakfast. This increase in fat burning is super important, but not for the reason you might think—both of the exercise groups in this six-week experiment lost the same amount of weight.

Lead author of the study Javier Gonzalez, Ph.D., explains, “Importantly, whilst this didn’t have any effect on weight loss, it did dramatically improve their overall health.”

Meaning, the fasted workout did show significant health benefits in terms of balancing blood sugar, which is crucial for mitigating health concerns like diabetes and heart disease. The reason these men were able to burn more fat during their workout is that their bodies were better able to respond to insulin. Their muscles even showed an increase in key proteins even though the men had training sessions and meals identical to the other two groups. 

“The group who exercised before breakfast increased their ability to respond to insulin,” Gonzales notes, “which is all the more remarkable given that both exercise groups lost a similar amount of weight, and both gained a similar amount of fitness. The only difference was the timing of the food intake.” 

“This work suggests that performing exercise in the overnight-fasted state can increase the health benefits of exercise for individuals, without changing the intensity, duration or perception of their effort,” co-author of the study Gareth Wallis, Ph.D., adds. Perhaps to truly experience the blood-sugar-balancing benefits of intermittent fasting, we need to take both our eating habits and workouts into account.

The next phase for this fasted workout research? Focusing on females. These scientists propose future studies that will measure whether a fasted workout could have similar effects for women. “We now need to explore the longer-term effects of this type of exercise and whether women benefit in the same way as men,” Wallis says. 

While exercise alone is beneficial for your health (no matter what age you start at!), it’s the time of day you decide to hit the gym that could significantly affect your blood sugar levels. If you’re not used to working out on an empty stomach, just be sure to bring a clean protein bar to avoid any hunger-induced rage after your gym session. Being hungry is a real issue, people.

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