What Your Gut Is Telling Your Brain (and Why You Should Listen)

The Gut–Brain Conversation You Can’t Afford to Ignore

If you’ve ever felt “butterflies in your stomach” before a big meeting or lost your appetite during stress, you’ve experienced your gut and brain talking to each other. But this connection goes beyond just gut feelings- it’s a two-way communication network known as the gut–brain axis, and it shapes everything from your digestion and mood to your immune system and energy levels.

In functional nutrition, we look at this connection as a feedback loop: what happens in your gut affects your brain, and what happens in your brain affects your gut. When that loop is balanced you feel calm, clear, and energized. When it’s not, it can lead to a range of symptoms, and not just in your gut- anxiety, brain fog, fatigue and other systemic issues can all be signs that your gut- brain communication is off.

The Gut–Brain Axis, Simplified

Your gut has its own nervous system known as the enteric nervous system, often called your “second brain.” It communicates with your central nervous system through the Vagus nerve, a highway of signals that carries messages back and forth between your digestive tract and your brain.

Your microbiome, aka the trillions of bacteria living in your intestines, play a key role in this process. They're not just there for digestion- they also produce neurotransmitters such as serotonin and GABA, influence inflammation, and even regulate your stress response.

When your microbiome is diverse and balanced, these signals promote well-being, but when it’s disrupted- from poor diet, antibiotics, stress, lack of sleep, or other factors- communication breaks down. The brain starts getting “distress signals” that can manifest as anxiety, low mood, fatigue, or poor focus.

Functional Nutrition and the Gut–Brain Connection

Traditional nutrition focuses on what you eat. Functional nutrition focuses on how your body uses what you eat — and how your systems interact.

From a functional standpoint, gut health is at the root of:

• Nutrient absorption (fuel for brain and body)

• Inflammation regulation (the foundation of chronic disease prevention)

• Detoxification and hormone balance

• Neurotransmitter production and stress resilience

When your gut isn’t functioning well, these processes slow down, and your brain is the first to notice.

Common Gut-Brain Imbalance Signs

• Bloating, constipation, or irregular digestion

• Cravings for sugar or carbs

• Anxiety, brain fog, or low mood

• Skin breakouts or inflammation

• Fatigue that isn’t fixed by sleep

Each of these symptoms is your body’s way of waving a flag that says, “Something's off in teh signals between my gut and brain."

3 Core Ways the Gut Impacts Your Mental and Physical Health

1. The Microbiome and Mood

About 90% of your serotonin- the “feel-good” neurotransmitter- is made in your gut. When your microbiome is balanced it produces serotonin efficiently, helping you feel calm, focused, and emotionally stable. Dysbiosis (an imbalance of gut bacteria) can lead to lower serotonin levels and increased anxiety or depression.

Functional Nutrition Tip: Feed your microbes what they need: fiber, polyphenols, and fermented foods.

2. Inflammation and the Leaky Gut Connection

A compromised gut lining (often called leaky gut) allows food particles and toxins to enter the bloodstream, triggering inflammation that can affect the brain. This inflammation has been linked to fatigue, brain fog, and even neurodegenerative diseases.

Functional Nutrition Tip: Focus on anti-inflammatory foods like berries, leafy greens, turmeric, ginger, and omega-3 fats.

3. Stress, Cortisol, and Digestion

When you’re under chronic stress, your body prioritizes survival over digestion, slowing down gut motility, changing stomach acid production, and reducing nutrient absorption. That’s why you might feel bloated, constipated, or lose your appetite when stressed.

Functional Nutrition Tip: Practice Vagus-nerve-activating habits daily — deep breathing, cold exposure, humming, or gentle yoga.

Functional Nutrition Strategies to Rebalance the Gut–Brain Axis

A functional nutrition approach doesn’t chase symptoms, it restores balance from the inside out. Here are five foundational strategies I use with clients:

1. Eat with balance and color: Aim for half your plate as plants, ¼ protein, ¼ healthy fats. The fiber and antioxidants feed your microbiome.

2. Diversify your foods: Rotate produce, spices, and fermented foods to build microbial diversity.

3. Hydrate and move: Proper hydration and gentle movement improve digestion and lymphatic flow.

4. Support your nervous system: Try a few minutes of deep breathing or mindful eating before meals to activate “rest and digest.”

5. Address root causes: Consider testing for microbiome health (GI-MAP), food sensitivities, or stress hormones (DUTCH test) for a personalized plan.

   
   

Why You Should Listen to Your Gut

Your gut isn’t just a digestive organ- it’s a key messenger that puts out signals to the rest of your body. When it’s inflamed, imbalanced, or stressed, everything in the body is going to know, but especially your brain, with it's direct lines of communication. Listening early allows you to correct course before symptoms become chronic.