Is Your Gut Holding You Back from Exercising? The Surprising Link Between Microbiome and Motivation

Struggling to Stay Motivated to Exercise? Your Gut Might Be to Blame

You’ve set your fitness goals. You know the benefits. But somehow, getting motivated to work out still feels like a battle.

What if the answer isn’t just about willpower?

A groundbreaking 2022 study published in Nature suggests that gut bacteria may play a critical role in motivating physical activity—at least in mice, and possibly in humans too.

The Study: Why Do Some Mice Love to Run While Others Don't?

In this study, researchers observed that some mice naturally ran more on their exercise wheels, while others barely moved. To understand why, they turned to machine learning to analyze a wide range of variables:

• Genetic differences

• Bloodstream metabolites

• Gut microbiome composition

The surprising result? Genetics explained very little. Instead, the composition of gut bacteria emerged as the primary factor influencing the mice’s desire to exercise.

Antibiotics Slashed Running Activity by 50%

When researchers administered broad-spectrum antibiotics to mice—effectively wiping out their gut microbiome—their voluntary running distance dropped by more than 50%. This wasn’t just a temporary slump; something fundamental had changed in their motivation system.

To find out what, the scientists examined gene expression in the striatum, a part of the brain linked to reward and motivation. They discovered that the antibiotic-treated mice showed significantly lower dopamine signaling compared to controls.

In other words, without gut bacteria, the mice didn’t get the same feel-good dopamine hit from running—and so they stopped doing it.

The Key Microbes: Eubacterium rectale and Coprococcus eutactus

Over several years of follow-up experiments, two specific bacterial species stood out:

• Eubacterium rectale

• Coprococcus eutactus

Both are known producers of fatty acid amides (FAAs), a type of signaling molecule. These FAAs interact with endocannabinoid receptors in the gut.

This interaction sets off a fascinating gut-brain cascade:

1. Activation of endocannabinoid receptors leads to…

2. Suppression of monoamine oxidase (MAO), the enzyme that breaks down dopamine.

3. Less MAO = more dopamine in the brain.

4. More dopamine = stronger motivation to keep exercising.

Essentially, these gut microbes create conditions that amplify the brain's reward response to physical activity.

Could This Apply to Humans Too?

That’s the million-dollar question—and studies in humans are already underway. While we don’t yet have definitive proof, preliminary data suggest similar mechanisms could be at play.

If confirmed, this would mean that manipulating the gut microbiome—through diet, prebiotics, probiotics, or even fecal transplants—could help improve exercise motivation in people struggling to get moving.

Bottom Line: It’s Not Just in Your Head—It Might Be in Your Gut

This research flips the traditional idea of motivation on its head. Instead of blaming laziness or lack of discipline, we may need to consider whether your gut bacteria are sabotaging your desire to move.

Of course, more research in humans is needed. But the early data are promising—and they point toward a future where microbiome science could help unlock not just better physical health, but the motivation to pursue it.

References

1. Dohnalová, L., Lundgren, P., Carty, J.R.E. et al. A microbiome-dependent gut–brain pathway regulates motivation for exercise. Nature. 2022;612:739–747. https://doi.org/10.1038/s41586-022-05525-z

2. Volkow ND, Wang GJ, Fowler JS, Telang F. Overlapping neuronal circuits in addiction and obesity: evidence of systems pathology. Philos Trans R Soc Lond B Biol Sci. 2008;363(1507):3191–3200.

3. De Vadder F, Grasset E, Holm LM, et al. Gut microbiota regulates maturation of the adult enteric nervous system via enteric serotonin networks. Proc Natl Acad Sci U S A. 2018;115(25):6458–6463.