Office Hours:Fiber Maxing Is Everywhere. Here's What It's Actually Doing to Your Gut

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
Fiber's having a moment. Now if you've been on social media lately, you've probably heard the term fiber maxing. People adding chia to everything down in Slim Huss, gaming for forty, fifty, and 60 grams of fiber a day. And the promise? Well, better gut health, better blood sugar, more weight loss, natural GLP one activation, hormone balance.

And here's the thing, fiber is incredibly powerful. In fact, most Americans are severely deficient. We need about half of what our bodies actually need, and that lack of fiber is contributing to a whole list of things called constipation, metabolic dysfunction like diabetes, inflammation, and even hormone imbalances. More fiber isn't always better. Like in functional medicine, we don't chase trends.

We ask better questions. So what's the goal, and who does this benefit? And what happens when we push a good idea just too far? Because if your gut is inflamed, if you have irritable bowel syndrome, if your microbiome is already fragile, dramatically increasing fiber is gonna make you feel worse, not better. So today, I wanna unpack this trend and what fiber actually does in the body and who truly benefits from increasing it and who needs to be careful and also how to build fiber into your diet in a way that supports your metabolism, supports your hormones, and your long term health without backfiring, because you don't want that, because it can get bad.

Fiber isn't a hack. It's not a cleanse. It's not a quick fix. It's a foundational nutrient that when used correctly can transform your health.

Dr. Mark Hyman
This episode was brought to you by Function. Get access to over 160 lab tests annually at functionhealth.com/mark.

Dr. Mark Hyman
With Labor Day long weekend here, we're bringing back one of our most popular conversations on a topic that's only gotten more relevant, fiber. From gut health and blood sugar to hormones and weight and natural GLP production, fiber can be incredibly powerful. But more isn't always better. In this Encore episode, we're breaking down the fiber maxing trend, who it may help, who should be cautious, and how to get the benefits without overdoing it. So enjoy the long weekend, and enjoy the episode.

Let's break it down. What is fiber maxing? Well, let's define this. It's exactly what it sounds like. Intentionally pushing your fiber intake way up.

We're talking thirty, forty, even 50 grams of fiber a day, sometimes more. Now people are doing it in very specific ways. Chia puddings loaded with seeds, psyllium husk and water every morning, ultra high fiber cereals, gut cleanse protocols, fiber powder, supplements stacked on top of Whole Foods. It becomes almost a badge of honor. How high can you go?

Well, why is this trending? Because fiber works. It helps with weight loss. It blunts blood sugar spikes. It feeds your microbiome.

It's good. It helps you feel full. It can even stimulate your body's natural GLP one hormone, the same pathway targeted by drugs like Ozempic. And for many women, fiber also helps support estrogen detoxification and hormone balance and gets everything working in the hormone scene. So the excitement makes sense.

So at its core, fiber maxing aims to accomplish something real. It's it's trying to help you feel fuller longer, so you don't eat so much. It lowers the spikes in insulin, which makes you gain weight. It's a fast forward hormone. It supports a healthier microbiome because fiber feeds the microbiome.

It helps you go to the bathroom and have regular bowel movements because you need fiber to go poop. And it assists in your body's clearing excess hormones through your gut. All these are really good goals, but here's the functional medicine lens. The goal isn't maximum fiber. The goal is metabolic resilience.

The goal is gut resilience. More isn't automatically better. Smarter is better. And the real question isn't how much fiber can I tolerate, which, you know, you get used to more and more? What does my body actually need?

What does my biology actually need? Now let's talk about why fiber actually matters. Because this isn't just about digestion. Fiber is one of the most important, powerful, underappreciated nutrients in the modern diet. First, fiber feeds your microbiome.

You're not just eating for yourself. You're eating for your gut bacteria. And your microbiome isn't just about, you know, gut comfort or regularity. It's about how the microbiome influences your immune system, your metabolism, your brain chemistry, even your mood. Now when certain fibers are fermented by gut bacteria, they produce something called short chain fatty acids, especially something called butyrate.

Smells bad, but it's really good for you. Butyrate helps strengthen the gut lining. It also reduces inflammation, and it improves your insulin sensitivity. It actually even helps prevent cancer, by the way. It's one of the key molecules that keeps your metabolic system running smoothly.

Now fiber also helps regulate cholesterol by binding bile acids and helping your body eliminate excess cholesterol. It slows glucose absorption, which means you have fewer blood sugar spikes, fewer insulin surges, and more stable energy, which is good because people want that. And for many people, especially women who are navigating a lot of the hormonal shifts that come with perimenopause and menopause or even PMS, fiber helps bind excess estrogen and also excess toxins in the gut. So they can be eliminated and don't affect your hormones, and that really helps create hormonal balance. Now there's a key distinction you should know about.

Not all fiber is the same. Now here's where nuance matters. Some fiber is soluble, meaning it dissolves in water. It forms this gel like substance, and it feeds your gut bacteria. Think oats, chia, psyllium.

Some fiber is insoluble. It adds bulk to your diet. It helps move things through your digestive tract. It helps you poop. Think leafy greens, vegetable skins, seeds.

And then there's fermentable versus nonfermentable fiber. You know, some fibers are easily fermented by the gut bacteria, which is really beneficial. But for someone with an irritable bowel syndrome problem or small intestinal bacterial overgrowth, too much fermentable fiber all at once can cause bloating, discomfort, and make things worse. Not that you don't need it eventually, but in the short term, you have to fix the problem. So when we talk about fiber, we we can't treat it like one single thing.

From a functional medicine perspective, fiber is a tool. And like any tool, it has to match the biology of the whole person using it. The goal isn't just more fiber. It's the right types of fiber in the right amounts for your body, not just anybody else. So fiber is not just about pooping, which is it's about metabolic signaling, which is very important.

So who actually benefits from increasing fiber? Thoughtfully, not recklessly. Who who benefits? When done correctly, high fiber intake is an incredibly powerful tool for the right people. And let's look at who that is.

First, anybody dealing with insulin resistance, by the way, which is almost ninety percent of the population, or prediabetes, fiber slows the absorption of glucose, which is really important. And that means fewer blood sugar spikes. It means less insulin flooding your system, and that's important because insulin is a fat storage hormone, and it means more stable energy throughout the day. And certain fibers actually stimulate your body's natural GLP one production, the same appetite regulating hormone that's targeted by popular weight loss medications like Ozempic, except this is your body doing it naturally. If you're struggling with cravings, energy crashes, or sudden stubborn weight gain around the middle, well, fiber can be a game changer.

Another great use of fiber is for people who are suffering from perimenopause or PMS or a lot of hormonal shifts. Now when estrogen levels fluctuate, many women experience a lot of changes in their bodies like fat distribution, maybe increased belly fat. Fiber also helps improve insulin sensitivity, which directly impacts this pattern. It also binds extra estrogen that's in your gut and supports proper detoxification, which means you don't have too much circulating estrogen in your body, which can cause all kinds of problems from PMS to breast cancer and many other things. This is not just a trendy claim.

This is just basic human physiology. Next big thing that fiber helps is constipation, which affects a lot of people. So when you have this slow transit time in your gut, when you increase fiber, and when things aren't moving, and you add the right types of fiber, gradually and then by the way, with enough water, because if you just have fiber without water, it's like cement, so you don't want to do that. When you do that, it can really improve going regularly, which is every day. I had a patient once, and I said, how often do go?

She goes, I'm regular. I said, well, how often do go? She goes, I go once a week. I'm like, that's not regular. She goes, it's regular for me.

It should be once or twice a day, folks. Okay? So it's basically you have to make sure you get the right amount for you and slowly build up. But ideally, fiber is really important for having regular healthy bowel movements. Listen.

If you want to protect your brain, start with your heart. I've been

Dr. Mark Hyman
saying that for years, and the science continues to prove it, because every thought, memory, and moment of focus depends on healthy blood flow. And the challenge is that changes in cardiovascular health can begin years before symptoms appear, long before a heart attack, long before memory problems, long before anyone realizes something is wrong. And that's why I pay attention to markers like APOB, lipoprotein, homocysteine, and inflammation. These markers can provide valuable insight into your long term cardiovascular health, and ultimately your brain. 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 with 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
The next big thing that can help with is your cholesterol. High LDL cholesterol, high APOB soluble fiber, things like steel cut oats, flax, psyllium. They can bind to the bile acids in your gut, and they help reduce the circulating cholesterol. And it's one of the most evidence based back benefits of fiber. So this is a lot of research on this.

And those who are also eating ultra processed diets, but honestly, you don't want to eat that anyway. But if if you if you eat those, those foods are just empty of fiber. They're just rapidly absorbed. They spike your blood sugar. They make you hungry.

They're just bad. And they make, you know, us all sick, which is what's happening in America today. So now if you're one of those people eats ultra processed foods, first of all, you shouldn't. But second of all, increasing fiber really helps correct this deficiency of fiber in your diet. So, yes, fiber maxing, done intelligently, and I don't like that term by the way, can be incredibly helpful.

But it works best when it's addressing a real metabolic need, not just chasing a trendy thing you've watched on Instagram or TikTok. Okay. So who should be a little cautious about eating too much fiber? Right? Let's talk about the other side of this conversation.

While eating fiber can be incredibly powerful, more isn't always better, if your gut is not ready for it. And this is where personalization and nuance matters. And a lot of people suffer from irritable bowel, from bloating, from what we call SIBO or small intestinal bacterial overgrowth. If you're struggling with these things, dramatically increasing fermentable fiber actually makes you worse in the short term. In the long term, it can help.

But in the short term, it's gonna cause a problem because fermentable fibers feed the bad bugs as well as the good bugs. And if bacteria overgrowing in the wrong place, like your small intestine, you're essentially pouring fuel on the fire, and you're gonna get more gas, more dissension, more discomfort. So in those cases, we don't start with more fiber. We start with healing the gut. And there's a very important method for doing that we call the five r program in functional medicine, but it's really important.

Second, anyone with active gut inflammation, whether it's inflammatory bowel disease or post antibiotic gut disruption or significant leaky gut symptoms, you need a more personalized approach because certain fibers will irritate an already inflamed intestinal lining. Again, the goal isn't volume. The goal is just to repair your gut. Another area to be cautious is thyroid patients, especially those taking thyroid medication. Because if you're eating a very high fiber intake, that can interfere with the absorption of certain medications if you take it too close together.

Doesn't mean avoiding fiber. It means about being strategic about timing, you're not absorbing the drugs as well as the sugar. Now I wanna talk about something that often gets overlooked. Some people start fiber maxing, but they're under eating protein. They're adding chia pudding, flax crackers, fiber cereal, but they're not getting adequate protein to support building muscle.

And especially as we age, muscle is critical for metabolic health, for blood sugar control, for longevity. Now if fiber crowds out protein, you're solving one problem and you're creating another problem. So be careful. The functional medicine rule is if your gut's inflamed, heal that first, don't overload it. Don't force feed the gut microbiome.

You want to make sure you have healthy bugs, build them up slowly, and slowly you build resilience and you can tolerate a lot more fiber. Fiber is very powerful, but only when your biology is ready for it. Okay. So if you're going to increase your fiber intake, let's do it in a smart way. First rule, go slowly.

Your microbiome adapts over time. Now if you jump from fifteen grams to forty five or 60 overnight, your gut is not gonna be happy, and you're gonna have issues. So it's slowly increased by about five grams of fiber a week. And then kinda let your system adjust. Second big point here is hydration is mandatory.

It's nonnegotiable because fiber absorbs water. And if you increase fiber without fluids, you're actually gonna worsen constipation. Fiber is like a sponge, and it needs water to do its job. And if you have fiber without water, it turns to cement, and that is no fun for anybody. Next, pair your fiber with protein.

That's critical because it helps with feeling full. It helps with blood sugar control, But protein also preserves muscle, and it stabilizes your metabolism, and it supports your long term overall resilience of your health. So every fiber forward meal should also include high quality protein. Next thing you wanna do is focus on whole food sources of fiber. The best fiber comes packaged with nutrients, phytonutrients and minerals, like lentils, beans if you can tolerate them, chia seeds, flax seeds, artichokes, berries, veggies of all kind.

A whole diversity of foods feeds a diverse microbiome. Next, be careful with ultra processed high fiber products. My rule is if it has a health claim on the label, do not eat it. It's bad for you. If it says high fiber, it's hiding something.

If it says high protein, it's hiding something like sugar. So be careful. Fiber bars are often loaded with sugar, artificial sweeteners. Cereals fortified with synthetic fibers are not good for you. It's manufactured to look healthy, but read the label carefully and basically follow my rule.

If it has a health claim on the label, don't eat it. Next, figure out what amount matters for you. Diversity of fiber is really important. So not just all from the same source like psyllium husk or flaxseeds. 30 of varied plant fiber is even more beneficial than sixty grams of one isolated supplement like flaxseeds or or psyllium husk.

So here's the takeaway. From a functional medicine perspective, the goal isn't to win the Fiber Olympics. It's to create a resilient gut, a stable blood sugar, balanced hormones, and sustainable energy. More is not the goal. Better is.

Now let's talk about why fiber is getting so much attention right now. GLP one. You've heard about Ozempic, Wegovy, all those medications that increase GLP one to reduce appetite and improve your blood sugar. But here's what most people don't realize. Your body already makes GLP one.

And one of the most powerful ways to stimulate it naturally is through fiber, especially soluble fiber and fermentable fiber. When fiber reaches your colon, it feeds your beneficial bacteria, and those bacteria produce short chain fatty acids. Those compounds signal your body to increase GLP one production, and that helps regulate your appetite, improve insulin sensitivity, and stabilize your blood sugar. So, yes, fiber can support natural appetite regulation. But here's the nuance.

Fiber alone is not a magic bullet. If you're not sleeping, if you're not strength training, if your protein intake is low, if your stress is chronically high, fiber is not gonna fix that. It's not gonna override those signals. So g l p one isn't just about food. It's about metabolic health as a whole.

Fiber is part of the solution, but it works much better inside a bigger framework of understanding metabolic resilience. Alright. Let's do a quick q and a on fiber. Is psyllium good? Well, yeah, if used strategically and if it's tolerated.

Is too much fiber bad? Well, yes, it can be bad in the wrong situations, and you can get bloating. You can get poor absorption of other things like minerals. So be careful. Next question.

Should I fiber max if I'm trying to lose weight? Yes. But with protein intake that's adequate and strength training or resistance training. Next question. Can fiber lower estrogen dominance, which means too much estrogen, which can cause weight gain, fluid retention, breast tenderness, PMS, hot flashes, all kinds of stuff, even cancer.

Yes. It actually can help by binding excess estrogen in the gut. And pro tip, flaxseeds are particularly good at this. Alright. Let's zoom out.

Fiber maxing isn't wrong. In fact, for lots of people, increasing fiber is one of the smartest changes they can make in their diet. But health doesn't come from extremes. It comes from alignment. The real goal isn't the maximum amount of fiber.

It's metabolic resilience. It's gut resilience. It's sustainable energy. It's sustainable hormones. If your digestion improves, your energy stabilizes, your cravings decrease, then you're on the right track.

But if you're bloated, you're inflamed, you're uncomfortable, that's data your body's giving you. Listen to your biology. If this episode helped you cut through the noise around the fiber trends, well, share it with someone experimenting with fiber maxing or trying to improve their gut health. And remember, the body responds to balance, not intensity. Smarter, not harder.

If you love that last video, you're gonna love the next one. Check it out here.