When To Exercise For Fat Loss

The Best Time for Exercise to Lose Fat

The morning exercise routine is so ubiquitous that it’s nearly a stereotype. We’re able to picture fit, high-flying executives who manage to close huge business deals, but will never compromise on their morning work out. Research shows that morning work outs are the best way to lose fat, in part due to our natural circadian rhythms.

Not so fast!

But while the morning workout is a regular phenomenon, it needs to be done correctly to maximize fat burning. Research shows that morning workouts are more effective than workouts later in the day, because we are exercising in a “fasted state.” Before we have breakfast, the only energy stores our body has available are those we’ve stored as fat, rather than the last meal we ate. For that reason, the fasted state makes the morning exercise routine far more effective than exercise later in the day for burning fat.

One study examined this by having 28 men eat a diet of 30-50% more calories than they usually take in. Half exercised regularly, and half did not exercise at all. Of those who exercised, half did so in the morning while fasted, while the other half did so after breakfast. Those who fasted were then allowed to eat the same breakfast after they had worked out. Between the two groups, those who exercised after breakfast put on fat, while those who exercised before breakfast – while fasting – put on no fat at all. This is a remarkable finding, especially when you consider that the group who did not exercise at all put on approximately 6 pounds of fat each.

The role of the circadian rhythm

In the morning, our bodies begin to pump cortisol – a stress and wakefulness hormone - to get ourselves awake and ready for the day. Because of this, working to in the morning usually comes with the added boost of being fresh and excited in the morning.

At the same time, our circadian rhythms are highly connected to the natural cycles of sunrise and sunset. This is likely why a study showed that those who took in bright sunlight within two hours of waking had lower body fat percentages than those who didn’t. 

Incredibly, our muscles too work on a sort of circadian rhythm. Research from Northwestern University in Chicago found that our muscle’s ability to utilize oxygen and work efficiently peaked when we were most awake. As well, they noted that our muscles were least likely to utilize oxygen efficiently – and burn calories – later in the day. 

The science is in: working out in the morning, before breakfast is the optimal way to lose fat. Utilizing Rthm can help you keep in shape more easily by helping to coordinate your lifestyle around your personal circadian rhythms.