Your Nervous System Controls Your Gut, Hormones, and Weight — Here's How to Fix It

Mark Hyman, MD

Dr. Mark Hyman is leading a health revolution—one focused on using food as medicine to support longevity, energy, mental clarity, happiness, and so much more. Mark Hyman, MD is a practicing family physician and an internationally recognized leader, speaker, educator, and advocate in the field of Functional Medicine. He is the founder and director of The UltraWellness Center, Founder and Senior Advisor for the Cleveland Clinic Center for Functional Medicine, a sixteen-time New York Times best-selling author, and Board President for Clinical Affairs for The Institute for Functional Medicine. He is the founder and chairman of the Food Fix Campaign, dedicated to transforming our food and agriculture system through policy.

He is a co-founder and the Chief Medical Officer of Function Health. He is the host of one of the leading health podcasts, The Dr. Hyman Show with 150+ million downloads. Dr. Hyman is a regular medical contributor to several television shows and networks, including CBS This Morning, Today, Good Morning America, The View, Fox, and CNN.

Connect with Mark

Podcast Facebook Twitter Instagram Youtube

Full Transcript

Automatically generated. Please forgive any typos or errors in the following transcript. It was generated by a third party and has not been subsequently reviewed by our team.

Dr. Mark Hyman  0:00
So yes, nervous system regulation may be the missing piece because you can't out supplement chronic stress signaling. You can't biohack your way out of a body that feels unsafe. Healing requires physiological safety.

Dr. Mark Hyman  0:11
Welcome back to Office Hours. As part of our summer replay series, we're revisiting some of the conversations that sparked the biggest response from our audience, and this one is one that clearly struck a nerve. Many of us spend years trying to optimize our health. We clean up our diet. We take supplements.

We improve our sleep and run every imaginable test. Yet sometimes we feel stuck. What made this episode resonate with so many listeners is that it explores a different question altogether. What if the issue isn't your gut, your hormones, your metabolism? What if the real problem is that your body truly never feels safe enough to heal?

In this conversation, I unpack the powerful role of the nervous system in regulating everything from inflammation and blood sugar to digestion, sleep, mood, and recovery. It's a perspective that has become increasingly important, and one that many people find surprisingly relevant to their own health journey. Whether you're hearing it for the first time or coming back for another listen, I think you'll find yourselves looking at stress, resilience, and healing in a completely different way. Let's dive in. This episode was brought to you by Function.

Get access to over 160 lab tests annually at functionhealth.com/mark.

Dr. Mark Hyman  1:16
Today I want to talk about something that might be the basic link in your health. You clean up your diet, you're taking your supplements, you're trying to sleep more, maybe even run labs and work with practitioners. But maybe you're still wired or exhausted or inflamed or just stuck in your health. What if your issue isn't your gut, your hormones, or your metabolism? What if the real issue is your nervous system?

Because here's the truth. Your body cannot heal if it thinks it's under threat. So today, we're gonna unpack what nervous system regulation actually means, and what a regulated nervous system looks like, and whether calming your internal stress response might be the key that unlocks healing. This isn't just about stress management, it's about biology. When I was in training to learn all about this stuff after medical school, because that was just the beginning, I took a course with a guy named Herbert Benson.

And he said that stress either causes or worsens ninety five percent of all illness. That's a big deal, and we should pay attention to that. In functional medicine, we talk a lot about inflammation. We talk about insulin. We talk about hormones.

We talk about toxins. All important. But underneath all of it is one master regulator, your nervous system. So what is your nervous system really? Let's simplify this.

You have two main branches of your nervous system. The sympathetic system, which is fight or flight, and the parasympathetic system, which is the rest, digest, and repair, the relaxation nervous system. And the sympathetic system mobilizes you. It makes your heart rate go up. It raises your blood sugar.

It redirects energy away from digestion and primes you for action, running from a tiger or getting in a fight. Not bad if you're surviving. It's essential. But the parasympathetic system is where healing happens. It's where digestion happens, where detoxification happens, where hormone regulation happens, where immune repair happens.

And then there's the vagus nerve, which is a major communication highway between your brain and your body. It connects your brain, your gut, to your heart, your lungs, to your immune system. So when we talk about nervous system regulation, we're really talking about your body's ability to shift fluidly between activation and recovery. The keyword is how to be adaptable here, or adaptability. Regulation doesn't mean being calm all the time.

It means you can experience stress and then return to baseline. There's a great book called Why Zebras Don't Get Ulcers by Robert Sapolsky, who's one of the key scientists who's helped us understand stress. And the reason zebras don't get ulcers is because when the lion chases them, they run like hell, freaked out. The lion catches one of the zebras, then goes about eating it, and all the other zebras just stop running. And they stand around the line while it's eating another zebra, and they their nervous system just calmed right down.

That's why they don't get ulcers. We just stay chronically stressed all the time. And the critical insight from functional medicine is this. Your nervous system sets the tone for every other body system. So what does dysregulation of your nervous system actually look like?

Well, most people don't realize they're dysregulated because they just feel normal. Let me paint you a picture. If you're chronically in sympathetic mode, that's sympathetic nervous system activation stress response, you might experience a lot of things. You might feel tired, but wired. You might be anxious and irritable.

You might have digestive issues, constipation or diarrhea, irritable bowel syndrome. You might have blood sugar swings. You might get panic attacks. You might wake up at two or three in the morning. You might have belly fat that won't budge.

Here's a little tip for you. Your nervous system is connected to your fat cells. And this is actually scientifically true. I've written about them in my books. The nervous system innervates fat cells or adipose tissue.

And when you're stressed, it makes them get more fat. It makes you gain more weight. That's not a good thing. It also affects hormone swings, autoimmune players. We know that just actually regulating your vagus nerve, they can regulate their vagus nerve through various implantable devices now and cure rheumatoid arthritis.

There was a study that I wrote about years ago where people who just journaled who had rheumatoid arthritis for twenty minutes a day about their authentic feelings had a dramatic reduction in symptoms better than most medications. Also, chronic stress raises cortisol. It causes then elevations in blood sugar. Because, you know, when you're stressed, you wanna have high blood sugar, but not all the time. And then when you have high blood sugar, you become insulin resistant.

And when you become insulin resistant, that causes inflammation. And when you have inflammation, that disrupts your hormones even more. It causes gut damage. It causes changes in your immune system. Now you're chasing symptoms.

When the upstream driver is your stress signaling response. Now on the other side, some people swing into what we call vagal shutdown. This is the freeze response. What does that look like? Well, fatigue, brain fog, low motivation, depression, feeling numb and disconnected.

Many people balance between both states, wired and exhausted at the same time. So tired and wired. It's not weakness, it's just nervous system dysregulation. So what does regulation actually look like? What does it look like to have a regulated nervous system?

It's not constantly being calm, it's resilience. And a regulated nervous system means you can handle stress without spiraling. You can digest your food well, you can sleep deeply, your mood's relatively stable, your heart rate variability improves, you recover faster from setbacks. Regulation is about recovery speed. It's about flexibility.

It's about metabolic safety. Because when your body feels safe, it turns on the repair system. When your body feels threatened, well, it prioritizes survival. And survival mode means shutting down long term healing. Okay.

So could this be the missing link to healing that we've been all looking for? Well, let's connect the dots. If you're trying to heal your gut, but you're chronically stressed, well, your microbiome shifts in response to the stress hormones. You literally change your microbiome with stress. If you're trying to balance hormones, but cortisol is elevated, it steals from the progesterone and other pathways that regulate your sex hormones.

You're trying to lose weight, and you're in constant fight or flight? Well, your insulin stays high. If you're dealing with autoimmunity, well, stress directly affects the immune signaling and your your immune system's health. So yes, nervous system regulation may be the missing piece because you can't out supplement chronic stress signaling. You can't biohack your way out of a body that feels unsafe.

Healing requires physiological safety. How do you regulate your nervous system? Let's make this practical. Number one, stabilize your blood sugar. Unstable blood sugar is interpreted as a threat.

And let me tell you how to do that. Start your day with protein, really important. Balance every meal with protein, healthy fat, and fiber. Reduce or I don't even like the word reduce. I would just say never eat ultra processed food.

There's no reason to eat Twinkies or Pop Tarts or Lunchables or Go Gurts or any of the million things that are in the grocery store shelves that are not actually food. Just eat food. Listen to Mike Tyson. Eat real food. This alone dramatically calms your stress signaling.

Next, use your breath. One of the fastest ways to shift into the relaxation response to the parasympathetic mode is your breath. So you can try this. Just inhale through your nose, and then take a second short inhale, and then exhale fully and slowly through your mouth. That long exhale activates your nervous system.

I just did it. I feel relaxed already. Two minutes can change your state. Literally, just try even five breaths can change your state. Just do five deep breaths, profound and rapid change.

You always have that accessible to you.

Dr. Mark Hyman  8:53
To keep your skin in check this summer, you have to check your health.

Dr. Mark Hyman  8:56
I know that's not what you're used

Dr. Mark Hyman  8:57
to hearing, but after decades in medicine, you need to know this. The glow you're chasing doesn't start with creams and serums. It starts in the blood. Your skin is an organ. In fact, it's your largest organ, and like everything else inside your body, your skin health depends on your nutrient status, your inflammation levels, your liver function, even your environment.

So you can spend money on the latest treatment, or you can look beneath the surface to get to the source. That's exactly why we built Function. Function gives you access to 160 plus lab tests annually that measure signals in your blood, including nutrients, liver health, inflammation, and hormones. You can also complete your health baseline by an annual MRI that helps you see organs, tissues, and other changes. Check your health at functionhealth.com/mark, and if you're one of the first 1,000 people this week, use the code mark twenty twenty six for a $50 credit or your $365 a year membership.

Dr. Mark Hyman  9:47
Next pro tip is build muscle. Muscle isn't just about looking good or aesthetics. It improves insulin sensitivity and increases mitochondrial density, but also enhances stress resilience. So strength training is one of the most powerful nervous system stabilizers that we have because muscle is your metabolic armor. Next, protect your sleep.

Because when your sleep is not good, you're in trouble. Sleep is when your body and your nervous system recalibrates. So how do you fix your sleep? Get morning light exposure. Sleep at a consistent bedtime.

Not always ideal, but can. Reduce your evening stimulation, so don't do stimulating things right before bed. Avoid blood sugar crashes before bed, because meaning don't eat a lot of sugar and starch at dinner. If you don't sleep, you can't regulate. So make sure you prioritize sleep.

Next, you want to create safety cues. The nervous system responds more to cues of safety than to positive thinking. So what is that? Nature, connection, community, touch, laughter, time offline, which I love. Your biology is always scanning for safety.

Just give it those signals. They're available to you. Alright. What are the myths about nervous system regulation and when it comes to nervous system function. Is nervous system regulation just meditation?

No. It's metabolic. It's relational. It's physiological. If I'm productive and high achieving, I must be regulated.

Not necessarily. I'm an example of that. You may be as you're running on adrenaline, which I did for many years. Can I biohack my way out of stress? Well, not if your lifestyle stays chaotic.

If I calm down, I lose my edge. Well, actually, regulation improves focus, performance, and clarity, so you do better. So here's the bottom line. A regulated nervous system is not a luxury. It's the foundation of healing.

If you feel stuck, whether it's weight gain, hormone dysfunction, gut issues, inflammation, just ask yourself, does my body feel safe? Because healing happens in safety. So start small. Balance your breakfast, lift something heavy, breathe for two minutes. Every morning I wake up and I do a breath work practice for five minutes.

It's amazing. I love starting my day like that. Go outside. Get some fresh air. Get some sunlight.

Prioritize your sleep. You don't heal by fighting with your body. You heal by teaching it that it's safe to repair. And when you do that, everything changes. Now if you want to go deeper, I want you to keep an eye out for my upcoming episode of my podcast with doctor Scott Scheer.

We're exploring the emerging theories and the practical tools for regulating nervous system and unlocking the body's healing capacity.

Dr. Mark Hyman  12:24
Take a listen to

Dr. Mark Hyman  12:24
this short clip from our conversation. Today, really wanna, like, have people who are listening to understand, you know, what what is going on with their their energy, what is going on with stress, and what what are the psychological and the physiological cause of stress, and how do we start kind of navigating this from a therapeutic perspective? Because like, we all want out of this. I as soon as like, yeah, I'm in this empathetic spiral of doom, and I don't want the hell out of this thing. So what what is it?

Explain it to us. Unpack it for us.

Dr. Scott Scheer  12:53
Thanks again for having me Mark. What I like to just describe here is it's not a diagnosis for people, this is more of a pattern. As you mentioned, it's an age old pattern, but I realized recently that it was really a significant discovery for me to understand that it's a spiral and it's a loop. You have sympathetic activation, which is your fight or flight, your nervous system being activated. You have mitochondrial dysfunction.

Mitochondrial dysfunction, mitochondria as all your listeners know is a part of their cells that make energy. The combination of sympathetic activation and mitochondrial dysfunction is a loop. And what happens here is that this loop can either start with mitochondrial dysfunction directly, that's what I call bottom up, or it can start with sympathetic activation from outside stressors, say it's your job, your relationship, you have a snoring partner that is snoring and you can't get to sleep at night, outside stressors or even like worse things like trauma or things that happen when you were younger that have maintained you in this place where you can't stay safe. Either way, whether it either starts with mitochondrial dysfunction directly or it starts with sympathetic activation externally, or for most people it's both, and then it's something that just makes you fall off a cliff. It could be

Dr. Mark Hyman  14:00
Well, pause you for a sec. Just define sympathetic activation.

Dr. Scott Scheer  14:03
Yeah.

Dr. Mark Hyman  14:04
Because people are like, what is that? And define, like, a little bit better mitochondria. Because these are these

Dr. Mark Hyman  14:09
are central to your thesis of your sympathetic spot. So let's get our terms right because

Dr. Scott Scheer  14:13
Yeah.

Dr. Mark Hyman  14:13
I think

Dr. Mark Hyman  14:14
if you like

Dr. Scott Scheer  14:14
Otherwise, you'll be just be talking doctors like

Dr. Mark Hyman  14:16
I'm sympathetic. You know? I'm sympathetic. No. No.

It's not that.

Dr. Scott Scheer  14:19
Yeah, no, good point.

Dr. Mark Hyman  14:20
So, yeah.

Dr. Scott Scheer  14:20
So, I feel sympathetic to those that are in sympathetic. The sympathetic nervous system, so sympathetic is your fight or flight part of your nervous system. So, it's running away from the proverbial saber tooth tiger, as we somehow always refer to it.

Dr. Mark Hyman  14:34
I know, right.

Dr. Scott Scheer  14:34
I don't know why. But you're getting chased by something. Yeah. But unfortunately, we're getting chased all the time in modern society, whether it's with our phones that are actively in our faces all the time, and doom scrolling at 03:00 in the morning, going, why is this the way it is? Or it's outside things like your job, your relationship, but we don't reward people resting and relaxing.

So the sympathetic nervous system is part of your autonomic nervous system. You have your sympathetic branch, which is your activation fight or flight, and you have your parasympathetic, which is your rest, digest, detoxify, and heal. But modern society doesn't reward that side, right? It rewards the hustle. Mean, in medical school, my friends and I had shirts that said sleep is for quitters.

Not surprising. I grew up in New York.

Dr. Mark Hyman  15:17
Surgeons don't have lunch, that was ours.

Dr. Scott Scheer  15:19
Yeah, there you go, same kind of thing. You hustle, right? You go and you grind, right? That's what we reward, and then unfortunately, that's how society has created this stress externally for us that we have to perform, we have to have more meetings, we have to do more, do more, do more all the time. And so instead of just running away from the saber tooth tiger and then hanging out the rest of the day because hopefully we lived, maybe we probably didn't, but in some cases we did, right?

Then you would have the time to relax because your nervous system would be activated and then it'd shut off, but that's not how modern society works anymore as you know. We're constantly stressed, constantly on pressure, constantly on meetings and that's that sympathetic activation and most of us kind of think we thrive in that environment, and we can for a little while, but the problem is that when you're sympathetic all the time, you're releasing hormones like cortisol, your neurotransmitters like norepinephrine and epinephrine Adrenaline. And adrenaline, yes, noradrenaline and adrenaline that are stimulating the whole system to work harder because if you're in that sympathetic nervous system activation all the time, I call it sympathetic overdrive, you're just shoving all those neurotransmitters and hormones out all the time and that causes deterioration in immune system function, in hormone function and in your mitochondria itself. So to define mitochondria, which we can do now, the mitochondria are part of the cell that helps make energy, right? When I was in high school, my daughter is in ninth grade, she learned she's got the basic cell, she just learned, she's like, dad, check out the basic cell.

It's got a nucleus, it's got cytoplasm, it's got Golgi bodies, and it's got this one little cool organelle called the mitochondria. I'm like, this is what I learned when I was probably that age too. You learn that the cell has one mitochondria, but that is far from the case. Some cells in our body have thousands of mitochondria per cell, and some cells, actually there's one human cell that has zero, and that's the red blood cell.

Dr. Mark Hyman  17:03
Yeah, the red blood.

Dr. Scott Scheer  17:04
Right. But most mitochondria per cell are in our reproductive organs. Eggs, oocytes, sperm are the number one number And

Dr. Mark Hyman  17:11
gotta swim, they have legal energy to swim.

Dr. Scott Scheer  17:13
Yeah, and the eggs have more though. Women have to create and make the baby, and so they have more. Yeah, yeah. But then just behind that is your brain, your heart, your liver, your musculoskeletal tissue. So detox, everybody, is hugely Yeah.

Ingenically intensive. Yeah.

Dr. Mark Hyman  17:26
Liver is.

Dr. Scott Scheer  17:26
People don't realize that. It's like if you need it, if you're gonna be able to detox, you have to have a huge amount of mitochondrial energy.

Dr. Mark Hyman  17:32
So you remember, you are not powerless in this process. You have far more influence over your biology than you've been told. When you learn to work with your nervous system instead of against it, you take back control of your health, and that's where real transformation begins. Thanks for joining me for office hours. I love diving into these topics with you.

Remember, you are the CEO of your own health, and every choice you make can move you closer to healing and vitality. I wanna keep these episodes as relevant and useful as possible. So tell me, what do you want to explore next? What questions are you wrestling with? What breakthroughs are you chasing?

Share your ideas in the comments on social media or through the link in the show notes. I'm listening. Until next time, keep taking charge, keep asking questions, and keep showing up for your health. If you

Dr. Mark Hyman  18:20
love this podcast, please share

Dr. Mark Hyman  18:22
it with someone else you think would also enjoy it. You can find me on all social media channels at Doctor Mark Hyman. Please reach out. I'd love to hear your comments and questions. Don't forget to rate, review, and subscribe to The Doctor Hyman Show wherever you get your podcasts.

And don't forget to check out my YouTube channel at Doctor Mark Hyman for video versions of this podcast and more. Thank you so much again for tuning in. We'll see you next time on The Doctor Hyman Show. This podcast is separate from my clinical practice at the Ultra Wellness Center, my work at Cleveland Clinic, and Function Health where I am chief medical officer. This podcast represents my opinions and my guests' opinions.

Neither myself nor the podcast endorses the views or statements of my guests. This podcast is for educational purposes only and is not a substitute for professional care by a doctor or other qualified medical professional. This podcast is provided with the understanding that it does not constitute medical or other professional advice or services. If you're looking for help in your journey, please seek out a qualified medical practitioner. And if you're looking for a functional medicine practitioner, visit my clinic, the Ultra Wellness Center at ultrawellnesscenter.com, and request to become a patient.

It's important to have someone in your corner who is a trained, licensed health care practitioner and can help you make changes, especially when it comes to your health. This podcast is free as part of my mission to bring practical ways of improving health to the public. So I'd like to express gratitude to sponsors that made today's podcast possible. Thanks so much again for listening.