Previous research has already suggested that working out in the morning, while quite difficult at times, can be the best way to build a sustainable habit. A new study suggests that men who work out pre-breakfast burn two times more fat.

Finding the time for a workout in our busy lives is not always easy. The morning can be a quick fix to that problem (ensuring that you get the workout in before things get crazy), but this means you need to wake up a bit earlier in the morning — and quite possibly, do physical exercise on an empty stomach. Some people “cheat”, and commute to work by walking, running, or biking, and then have breakfast at work. Professional athletes also often start their routine pre-breakfast.

But is there any benefit to this?

The new study seems to suggest so, at least for men — and it might have something to do with intermittent fasting.

In the study, co-author Javier Gonzalez from the University of Bath in England conducted two experiments on men who were either overweight or obese. In the first study, Gonzalez and colleagues had participants do one cycling workout without breakfast, and then on another day, do the same exercise after a light breakfast. In the second experiment, 30 men trained consistently for 6 weeks — one working out pre-breakfast, the other post-breakfast.

The team found that participants working out without eating in the morning burned two times more fat than the others. This didn’t translate into any weight loss or fitness increase — the after breakfast group was simply more likely to burn carbohydrates than fat.

Insulin is a hormone that helps cells absorb sugar from the bloodstream, and use it for energy later. Insulin and obesity go hand in hand — an overproduction of insulin has been linked to obesity, and increased insulin levels are also a cause of obesity; the causation is not exactly clear, but there is a definite relationship between the two.

Insulin levels drop during the night, as the body relies on stored fat for energy (the basic idea behind intermittent fasting). Ultimately, this study suggests that training consistently before breakfast can help the body learn to use fat for energy and moderate insulin sensitivity. While this might not help you lose more pounds, it might reduce the risk of obesity. But it’s still not entirely clear what the best time of day to work out is.

Pre-workout meals help with muscle recovery, particularly during strength training (and also to cardio training, to a lesser extent). Also, working out on an empty stomach can be a daunting task, particularly early in the morning. In the end, while the study raises some important points about the body’s metabolism during workouts, the best time to work out is the time that works for you.

The study has been published in The Journal of Clinical Endocrinology and Metabolism.