Working out in the morning is a consistent way to to build an exercise habit, or at least ensure it gets in before the day gets crazy. Although the idea isn’t palatable for everyone, new research suggests pre-breakfast workouts could enhance one of exercise’s important health benefits.

A study released Friday in The Journal of Clinical Endocrinology and Metabolism shows that when men exercised pre-breakfast, they burned twice the amount of fat than men who waited until after breakfast. That fat didn’t translate to extra weight loss, which backs up earlier research suggesting that fasted workouts may not actually affect weight loss. However, the team reports that pre-breakfast exercise could help regulate “key aspects of metabolic health” in men who are overweight and obese.

Those “key aspects” included reducing excessive amounts of insulin, a hormone that helps cells absorb sugar from the bloodstream, where it can then be used for energy later on. Some research has linked overproduction of insulin to obesity in the past, but it’s also a harmful consequence of obesity. Ultimately, these authors suggest that pre-breakfast workouts could help moderate insulin sensitivity, which could help people with obesity get things under control

Working out in the morning, before breakfast, could maximize exercise's effects on metabolic health. Pxhere

Study co-author Javier Gonzalez, Ph.D., an associate professor of human physiology at the University of Bath in England, tells Inverse that his study participants seemed to handle the pre-breakfast workouts well. They didn’t find their empty-stomach workouts any harder physically, and he suggests that it’s a fairly seamless way to integrate workouts into a morning routine.

“I think a lot of athletes already use this strategy, and many people do this when they actively commute to work and then have breakfast at work,” Gonzalez says. “We think these are exciting findings and could be used already by some people to maximize the health benefits of exercise.”

In this study, Gonzalez and his team conducted two experiments on men who fit the bill as overweight or obese. The first study was short-term: The men all either did one cycling workout without breakfast, and then, on a different day, did another workout after a breakfast of cornflakes and toast). In the long-term experiment, 30 men consistently trained for six weeks. One group ate pre-workout breakfasts and the other group didn’t.

At the end of each experiment, Gonzalez and the team found that both groups of men lost about the same amount of weight and saw comparable increases in fitness. But the differences between the groups showed themselves deep inside their bodies, particularly in their responsiveness to insulin.

During the six weeks of training, the men who didn’t eat before they exercised reduced their levels of insulinemia after meals, which is when there’s too much circulating insulin. In turn, their sensitivity to the insulin that was there increased.

"Many people do this when they actively commute to work and then have breakfast at work."

Additionally, they found that the men who exercised before breakfast used twice as much fat for energy, as opposed to carbohydrates during their workouts. Ultimately, the study’s authors believe the key factor behind the fat burning aspect comes down to the effects of fasting overnight. As insulin levels drop at night, the body is forced to rely on stored fat as a source of energy, which is the key idea behind intermittent fasting.

This study provides backing to the idea that training consistently before breakfast, like these men did, can help the body learn to use fat for energy. But it also suggests that it can help them keep insulin levels in check as well.

However, there are some good reasons that a pre-breakfast workout may not work for all situations. Some work has suggested that pre-workout meals can aid recovery. Going hungry may not be best for certain kinds of workouts, like strength workouts, which place far different energy requirements on muscles than low-intensity cardio does.

But, ultimately, it depends on what your goals for exercise are. Working out before breakfast, according to this study, appears to have clear health-enhancing effects that could help counteract some of obesity’s long, lasting, and dark health effects that aren’t as apparent on the surface.

Partial Abstract:

Results: Results: Acute Study - exercise before versus after breakfast consumption increased net intramuscular lipid utilization in type I (net change: -3.44±2.63% versus 1.44±4.18% area lipid staining, p < 0.01) and type II fibres (-1.89±2.48% versus 1.83±1.92% area lipid staining, p < 0.05). Training Study - postprandial glycemia was not differentially affected by 6-weeks of exercise training performed before versus after carbohydrate intake (p>0.05). However, postprandial insulinemia was reduced with exercise training performed before, but not after carbohydrate ingestion (p=0.03). This resulted in increased oral glucose insulin sensitivity (25±38 vs -21±32 mL×min-1×m-2 87 ; p=0.01), associated with increased lipid utilization during exercise (r=0.50, p=0.02). Regular exercise before nutrient provision also augmented remodelling of skeletal muscle phospholipids and protein content of the glucose transport protein GLUT4 (p<0.05).

Conclusions: Experiments investigating exercise training and metabolic health should consider nutrient-exercise timing, and exercise performed before versus after nutrient intake (i.e., in the fasted state) may exert beneficial effects on lipid utilisation and reduce postprandial insulinemia.