The Gut Microbiome's Role in Muscle Mass: A Critical Connection

Muscle Mass – It’s not just for show

Muscle mass doesn’t get the respect it deserves. In the 1960s, as the running boom emerged, the benefits of muscle mass to overall health were largely ignored as sports medicine experts, such as Dr. Kenneth Cooper (author of the classic book Aerobics), focused on the (very real) benefits of aerobic exercise. Even now, many people associate large muscles with vanity – that bigger muscles are simply cosmetic rather than functional in their appeal. In reality, muscle mass is a critical marker of overall health. Low levels of muscle mass are strongly related to an increased risk of mortality. 

The Gut Microbiome and Muscle Mass

Muscle mass is directly related to strength and your ability to perform functional movements, such as standing up from a chair. Further, muscle mass, independent of strength, is associated with longer life. Higher amounts of muscle mass indicate a healthier hormonal environment, including a healthier gut microbiome. Specifically, higher levels of short-chain fatty acids, metabolites produced by our gut bacteria, are associated with greater muscle mass. Short-chain fatty acids improve gut function and other diverse positive roles in metabolism, including appetite regulation, insulin sensitivity, and inflammation.

Can you modulate the gut microbiome?

As indicated above, much research backs the relationship between a healthy gut microbiome and greater muscle mass. Does the relationship work both ways, though? Can you improve the health of the gut microbiome by using weight training to add muscle mass? Here, the research is less clear. A 2024 review paper looking at the relationship between resistance exercise and the gut microbiome found no significant changes in the composition or diversity of the gut microflora after training. However, there are some indications that resistance training can reduce overall levels of gut inflammation.

So, don’t count on exercise alone to improve your gut health. What about diet? Can we eat to improve the diversity of our gut microbiome? Happily – the answer is yes!  Eating more fiber (prebiotics) and probiotics (foods containing helpful bacteria, such as yogurt) can enhance the growth of beneficial bacteria in your gut. And consuming pre- and probiotics can also optimize increases in muscle mass! Supplementing with pre- and probiotics has been found to enhance the absorption of ingested protein and measurably increase muscle mass gains above protein ingestion alone.

Further, improved wound healing (which is a sign of effective protein synthesis) has been documented following Inulin (a prebiotic) supplementation. Overall, there is strong evidence to believe a diet consisting of varied fruits, grains, and vegetables (fiber sources) and some fermented foods such as yogurt, sauerkraut, kimchi, etc., will help to optimize your gut health and your ability to gain muscle mass. 

To achieve your best and longest life, a combination of resistance and aerobic exercise, with a varied, high-fiber diet including some fermented foods, looks to be the best recipe. Please feel free to share your stories of resistance training and gut health in the comments below. To staying swole and in good health!

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