The Gut-Brain Connection: How Your Microbiome Influences Mood, Metabolism & Cravings

Our gut-brain connection is no longer considered a theory - it's one of hte most well-established areas of modern neuroscience and microbiome research. Since the early 2000's, thousands of studies have shown that the trillions of microbes living in each our our guts communicate continuously with our brain, influencing our mood, appetite, metabolism, immune function, and even food cravings. Most people think of the gut as a digestive organ. In practice, it functions more like a command center—continuously communicating with the brain through what we call the gut–brain axis. This communication shapes how you feel after meals, how clearly you think during the day, and how your body regulates appetite, energy, and fat storage.

What's wild is I've felt this for myself..like so many others. Back in the days when I was diagnosed with Crohn's disease, (an autoimmune disease where the body attacks the small intestines) being the determined self that I was, I put myself on the Specific Carbohydrate diet. The principle was that if you stopped feeding the 'bad bacteria' the foods they were eating to stay alive, I would be able to starve them off, they'd die, and then my gut lining would finally begin to heal. Like this time, and many times of my life when I've gotten off of these specific carbohydrates - processed wheat foods, oatmeal, rice, potatoes, legumes, processed sugar - I could literally 'feel' the bad bacteria throwing tantrums within me as I stopped feeding them. They would lash out with my body experiencing headaches, flu-like and detox symptoms, major fatigue, diarrhea and bloating. Those tiny critters would do anything to keep me on their 'crack'.

A few data points help bring this into focus. Roughly 90–95% of serotonin

—a key neurotransmitter involved in mood and well-being—is produced in the gut. The vagus nerve provides a direct, two-way line of communication between the gut and the brain, and emerging research shows that shifts in the microbiome can influence stress reactivity, cognition, and even decision-making around food. In metabolic research, the composition of the microbiome has been linked to insulin sensitivity and weight regulation , helping explain why two people can eat similarly and experience very different outcomes.

In my work, I often see clients who feel “off"—low energy, brain fog, heightened cravings, or a sense that their metabolism has slowed. When we step back and look at the gut, we frequently find the missing piece. The microbiome is not just responding to what you eat; it is actively shaping what your body does with that information.

My Approach: Read the Signals, Then Correct Them

As a functional nutrition practitioner, I approach the gut–brain connection through a root-cause, lab-informed lens. We assess what is happening in the microbiome, how well digestion is functioning, and how the nervous system is influencing these processes.

In my practice, I don’t rely on guesswork when it comes to the gut—I use targeted testing. One of the most valuable tools I use is a comprehensive GI Microbiome Test, which allows us to assess bacterial balance, inflammation, and digestive function at a deeper level. This gives us a precise roadmap to restore the gut and improve the signals being sent to the brain and metabolism.

From there, we build a personalized strategy that integrates nutrition, movement, and

nervous system regulation—what I refer to as my “three doctors.” When these are aligned,

the signals your body sends and receives begin to shift in your favor.

How the Gut Shapes Mood, Cravings, and Metabolism

The microbiome influences mood in a very real, physiological way. When beneficial bacteria are supported, they help regulate neurotransmitter production and reduce inflammatory signalingthat can impair brain function. When the gut is imbalanced, those same pathways can contribute to low mood, irritability, and reduced mental clarity. This is one reason people often notice improved emotional stability when their digestion improves.

Cravings are another area where the gut exerts powerful influence. Certain microbial patterns are associated with increased preference for sugar and refined carbohydrates. This is not simply a behavioral issue—it is a biological feedback loop. When the microbiome is out of balance, it can reinforce patterns that keep it that way. When we improve the environment of the gut, those signals often quiet down, and appetite becomes more stable without forcing restriction.

Inflammation is the third major connection point. A compromised gut lining or imbalanced

microbiome can increase inflammatory signaling, which affects both brain function and

metabolic efficiency. This is where clients report feeling mentally foggy, physically fatigued, and metabolically “stuck.” When we reduce that inflammatory load and improve gut integrity, both cognitive clarity and metabolic responsiveness tend to improve.

Nourishing Your Inner Ecosystem

The foods and nutrients we consume every day act as fuel for this micro biome, which is an ecosystem of beneficial and opportunistic bacteria. Dietary fiber, polyphenols from colorful fruits and vegetables, omega-3 fatty acids, fermented foods, and compounds such as sulforaphane from broccoli microgreens can help create an environment that supports a more diverse and resilient, microbiome. In turn, a healthy ecosystem produces beneficial compounds that help strengthen our gut lining, reduce inflammation, support metabolic health, and send healthier signals throughout the body - most especially to our brain.

What You Can Start Doing Now

If there is one takeaway I want you to leave with, it’s this: the gut responds quickly to consistent, supportive inputs. You don’t need to overhaul everything overnight.

1. Start by slowing down how you eat, chewing more thoroughly, and allowing your body to enter a true “rest and digest” state during meals. Build your plate around whole foods with fiber diversity—different colors, textures, and plant sources—to feed a wider range of beneficial bacteria.

2. Pay attention to how you feel after eating, not just what you ate. That awareness alone begins to change behavior.

3. Just as important is protecting your nervous system. Sleep, stress, and pacing matter.

4. A well-designed nutrition plan or 'diet' cannot override a body that is constantly in a stress response. When you support both the gut and the nervous system together, the communication between them improves—and that is where real change happens. Engaging in stress management techniques literally sends signals to our microbiome. Such techniques include conscious cooking and mindful eating where you're taking your time without distractions, having a therapist to talk to, walking in nature with your feet grounding the earth or getting a massage, acupuncture or stretching.

Final Thought

Your cravings, your mood, and your metabolism are not random. They are responses to

signals—many of which begin in the gut. When you strengthen your microbiome and reduce the noise of inflammation and stress, your body becomes more stable, more efficient, and more aligned with your goals. Taking care of your gut is not just about digestion. It is one of the most powerful ways to support

your brain, your energy, and your long-term health.

Work With Dr. Stefanie Basso

If you’re ready to understand your gut and metabolism at a deeper level, you can begin with a 60-minute Functional Nutrition Strategy Session, where we assess your current symptoms, lifestyle patterns, and potential root causes.

In health,

Dr. Stefanie Basso, PhD, BCFNP