July 13

What You Didn’t Know About Women and Running


In the world of women's health and women's fitness, there are numerous physiological differences between men and women that continue to intrigue researchers. One such captivating discovery is that women tend to utilize more fat for fuel during exercise compared to men. Does that statement surprise you? The reason behind it might. This intriguing phenomenon is attributed to several factors, including the composition of muscle fibers and the influence of hormonal cycles in women. 

As we discuss why women are more efficient at using fat stores as fuel than man, we want to thank our friends at Gnarly Nutrition for providing us with this knowledge. If you haven't checked out some of Gnarly's nutrition resources yet, you absolutely should! They're chockful of knowledge and have some of the best supplements on the market. 

Now, let's dive in! Why are women more efficient at using fat stores than men?

The Dominance of Type 1 Muscle Fibers in Women

Research has revealed that women possess a higher proportion of type 1 (aka slow-twitch fibers) muscle fibers compared to men. These slow-twitch muscle fibers have a high resistance to fatigue, making them great for endurance activities. Type 1 muscle fibers have slower twitch speeds and are fairly fatigue resistant, which makes them great for endurance activities! We also know that fat is how our bodies store energy "for a rainy day." That's a simplified version of what fat does, but you get the gist. As a result, the function of type 1 muscle fibers — endurance activity — is compatible with the long-term nature of fat as energy. So, these muscle fibers are better adapted to utilize fat as a fuel source.

Conversely, fast twitch muscle fibers (type 2) muscle fibers have higher twitch speeds and are more prone to fatigue. These fast twitch fibers rely on readily available glycogen, a form of carbohydrate energy that the body can easily use. If glycogen isn't available, these muscle fibers are at a severe disadvantage. But not type 1 fibers! Nope, those perseverant muscles excel at extracting energy from fat stores, so they can work longer. These distinct types of muscle fibers, with their respective characteristics, play a significant role in determining performance and abilities in various physical activities.

With a higher proportion of type 1 muscle fibers compared to men, women consequently may possess a physiological advantage in endurance activities such as long-distance running, cycling, or swimming. This distinction showcases the unique capabilities of the female body when it comes to fuel utilization during exercise. The ability of type 1 muscle fibers to efficiently utilize fat as a fuel source contributes to their endurance and sustainability in activities that require prolonged effort. This physiological advantage in endurance-related activities is attributed to the higher prevalence of slow-twitch muscle fibers in women.

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The Influence of Hormonal Cycles

Another intriguing aspect of fat utilization in women is its variation throughout the menstrual cycle. Hormonal fluctuations impact how women store and use fat, leading to changes in energy metabolism. During the first half of the menstrual cycle, estrogen levels rise, promoting the use of fat as a fuel source. This shift is believed to enhance endurance capabilities during this phase. However, during the second half of the cycle, progesterone levels increase, potentially altering fat metabolism and making it less favorable for endurance activities. Understanding these hormonal influences can assist women in tailoring their exercise routines to optimize performance and energy expenditure during different phases of their cycle.

Fat Isn't Bad

Eighties diet culture had it all wrong. Let's be honest, the vast majority of diet culture is ill informed or only shows part of the picture. Sensible people know that a whole foods, balanced diet is the best way to nourish your body, and fat needs to be part of that nutrition. To support optimal fat utilization, it is crucial for women (and men) to maintain an adequate fat intake in their diet. Approximately 20% of daily caloric intake should be derived from healthy fat sources. Fat intake plays a significant role in the absorption of fat-soluble vitamins, including Vitamins A, D, E, and K. These vitamins are essential for various bodily functions and maintaining overall health. Therefore, ensuring sufficient fat intake is not only important for exercise performance but also for the overall well-being of women.

What's Next?

We are curious to hear of new research regarding the way different energy stores are used by women and men in exercise. Understanding how our bodies differ can help us all key-in our training and nutrition. For now, women can relish in this fun, biological victory over men while honing their training regimens to be nourishing at all stages.

It's critical that women maintain adequate fat intake to supporting the absorption of fat-soluble vitamins and overall health. Further, tailoring training programs to complement the hormonal cycle can help women feel energized all cycle long. If you've always wondered why you have spells of being more energized and others where it's much harder to exercise, start tracking your cycle and read about the role that hormones play in our metabolism, energy, and more. It's not only eye-opening, it's liberating! By recognizing and leveraging these unique aspects of the female physiology, women can enhance their exercise performance and make informed decisions regarding their training regimens.


Fitness, gnarly, Gnarly Nutrition, Nutrition, running, Training

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