Does Having a Healthy Gut Make You More Fit?

Key takeaways: New research presented at the annual meeting of the American Physiological Society suggests a link between gut health and overall fitness levels, but the connection between the two was only observed in men. One of the scientists involved in the research, along with doctors and sports nutritionists, weighs in.

You probably think of fitness level as the result of careful training and genetics, but new research suggests that there’s something else that could influence how in shape you are: your gut microbiome.

The findings, presented at the annual meeting of the American Physiological Society, which takes place from April 23 to April 26 in Minneapolis, Minnesota, make a case for focusing on your gut health during training to support performance. But does having a balanced microbiome automatically mean you’re more fit? We asked experts to find out.

How the Researchers Discovered a Link Between the Gut and Fitness

The researchers had 27 participants do a cycling test while analyzing their VO2 max, or the maximum amount of oxygen your body can use during hard exercise, and maximal metabolic steady state, which measures the level of heavy exercise they could sustain.

The participants also provided a fecal sample within 48 hours of the test to analyze their gut microbiome. While the gut microbiome is the community of microorganisms—including bacteria, fungi, and viruses—that live in the digestive tract and influence health, a diverse gut microbiome (more on what that means below) is typically seen as a marker of a healthy gut.

After comparing the data, the researchers found that good alpha diversity—the overall abundance and quality of microbes in a person’s microbiome—was linked to higher fitness. However, that link was only observed in men, not women.

The findings represent the “first step toward understanding this topic and to begin to establish the relationship between microbiome diversity and aerobic performance parameters in humans,” says Kristina V. Binder, a researcher on the study and graduate student in the Department of Human Physiology at the University of Oregon.

It’s crucial to note that the findings don’t prove that a diverse gut microbiome makes you more fit, but that a link between higher fitness and a varied microbiome may be evident.

Does Having a Healthy Gut Equal Better Fitness?

No. Having a healthy, diverse gut microbiome doesn’t magically make you more fit. But it could play a supportive role, along with targeted training, according to Dr. Caitlyn Mooney, an assistant professor in the department of sports medicine at Vanderbilt University Medical Center.

If that news bums you out, you’ll be happy to learn that having a healthy gut is still beneficial to your well-being. “We do have evidence that the gut microbiome is more diverse and healthy with regular exercise,” Mooney says. “Regular exercise is known to benefit nearly every organ system in the body.”

The gut microbiome also influences energy metabolism, blood sugar, and inflammation in the body, says Albert Matheny, a sports nutritionist, personal trainer, and co-founder of SoHo Strength Lab, a private training practice in Manhattan, New York. “All of those can impact performance,” he says.

“Certain gut bacteria produce short-chain fatty acids, which improve our metabolic efficiency,” Mooney says. The gut microbiome may also influence the function of mitochondria (the powerhouse of cells) and pathways in the body that influence how oxygen is used, she says.

But Mooney says the relationship between the gut microbiome and fitness likely goes two ways. “Regular exercise itself is a driver of healthy guts and healthy guts may allow us to be more fit,” she says. “Additionally, a healthy gastrointestinal tract allows efficient fueling for well-trained athletes.”

Why Did a Healthy Gut Only Seem to Benefit Men’s Fitness?

Binder stresses that the findings are “preliminary,” adding that more data is needed. Mooney agrees. “I would also be cautious interpreting sex-based differences from a single small study,” she says.

However, there are a few theories of what could be behind this. “We think that fluctuating female sex hormones across the menstrual cycle could be playing a role, or the larger muscle mass generally seen in men could mean a greater interaction—or signal—for the microbiome to change,” Binder says.

Still, Binder says that she and her fellow researchers “don’t really know” what’s behind this—but they plan to study it more. “Women should be able to reap the same benefits in microbiome diversity as men with exercise,” she says. “It just may take a little longer, or they may need to adjust their intensity. We cannot really speculate on the best way to go about this yet.”

How Can You Diversify Your Gut Microbiome?

Again, the role of gut microbiome diversity and fitness is still being explored. But a diverse gut microbiome is already linked to good health.

To diversify your gut microbiome, Matheny suggests eating a wide variety of whole foods, including fiber, fermented foods, fruits and berries, and avoiding overly processed products. Regular exercise and avoiding unnecessary antibiotic use can help, too, Mooney says.

To enhance your performance, Mooney recommends continuing with your workouts. “Training will remain the primary driver,” Mooney says. “Gut microbiome supports your ability to train consistently, recover well, and adapt, but is not a shortcut for training and recovery.”

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