The fitter you are, the faster your body can burn fat for energy

Elizabeth Millard
·3-min read
Photo credit: Brian Barnhart
Photo credit: Brian Barnhart
  • Endurance athletes burn fat faster for energy, and women are better at it than men, according to recent research based on two studies.

  • The reason may be related to the fact that women tend to have a greater reliance on fat as a fuel source, which could give them a metabolic advantage.

  • Long runs tend to deplete your glycogen stores, and if your body is able to burn fat for energy better, it can help minimise the impact.

Here’s more proof that regular exercise makes your body’s processes more efficient: Endurance athletes burn fat faster, and women are better at it than men, according to recent research based on two studies.

The first study, published in the International Journal of Sport Nutrition & Exercise Medicine, looked at 73 women and men who reported different levels of regular physical activity before participating in the study. The people in the study performed cycling trials anywhere between seven and 28 days apart, and researchers tested each person’s resting metabolic rate (the number of calories burned when your body is completely at rest) and peak fat oxidation (a measure of how quickly you break down fatty acids) right before each cycling trial.

Those who exercised regularly before participating in the trials—especially women—burned fat more efficiently while cycling, researchers concluded.

In a second, related paper published in Experimental Physiology, the same researchers dug a little deeper into potential factors for why this might be the case. They took fat and muscle biopsies from the study’s participants and analysed differences in proteins that might be affecting their ability to burn fat.

They found that some proteins in muscle play a major role in breaking stored fat into smaller fatty acids that other proteins then transport into cells—which are then turned into fuel for energy. Those who exercised regularly had more of these proteins.

Neither exploration could pinpoint why women might see a greater effect than men, but it may be related to the fact that women tend to have a greater reliance on fat as a fuel source, which could give them a metabolic advantage, according to lead author Oliver Chrzanowski-Smith, Ph.D., who works in the Department of Health and Social Care for the Isle of Man in the U.K.

He also told Runner’s World that women might have increased fatty acid delivery to skeletal muscle in general, and more estrogen receptors may also play a role in fat oxidation.

For both women and men, the biggest takeaway is that regular activity boosts the body’s ability to use fat as a fuel source; Chrzanowski-Smith said that’s what builds more proteins in skeletal muscle and creates that 'fat as fuel' effect in the body.

Regular training is especially important for endurance athletes, he added, since long rides tend to deplete those crucial glycogen stores, and being better able to burn fat can help minimise that impact.

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