Fiber for Athletes: How Much Fiber Do You Need a Day?
- 4 hours ago
- 6 min read
Fiber has been having a moment lately, with social media trends like “fibermaxxing" on the rise and countless fiber-rich products hitting the market. While I’m happy to see fiber stealing some of the spotlight away from protein, it’s easy to get the message that more is always better. When it comes to fiber for athletes, that's certainly not the case.
Although fiber isn't digested and absorbed like other nutrients, it is incredibly important for gut health, heart health, blood sugar regulation, recovery, and overall health. The problem is that fiber is a double-edged sword for athletes. If you eat too much at the wrong time, you could end up feeling bloated, dealing with GI distress, or struggling to meet your fueling needs, all of which can have negative effects on performance.
So…how much fiber is appropriate for athletes?
In episode 142 of The Eat for Endurance Podcast, Sports Dietitian Angie Dye, MS, RDN, CSSD joins me to answer this question and break down everything that active people need to know about fiber.
Angie and I discuss:
What fiber is and why it's so important
Different fiber types and how much you should be eating each day
How fiber supports gut health, blood sugar, heart health, and more
When to eat fiber and when to avoid it around training and racing
What "fibermaxxing" is and if you should do it
High-fiber foods we recommend for athletes
Whether fiber supplements and fortified foods have a place in your diet
Special considerations for vegan and vegetarian athletes
Practical ways to increase your fiber intake without upsetting your gut
By the end of this episode, you'll understand why fiber deserves a place in every athlete's nutrition plan, how to strategically time it around exercise, and why getting your fiber from whole foods is the best approach.
Fiber for Athletes: Why It's So Important
When athletes hear the word fiber, they often think about limiting it before exercise to avoid GI distress. And I get it…no one wants to frantically search for a bathroom mid-run. So while there is truth to that, fiber still is an incredibly essential part of an athlete's diet.
As Angie explains, fiber acts as "fertilizer for our good bacteria."
We don't actually digest fiber ourselves…our gut bacteria do. In the process, they produce compounds that support gut barrier function, immune health, nutrient absorption, metabolism, and overall digestive health.
Fiber also:
Promotes more stable blood sugar levels by slowing digestion down
Increases satiety, which helps you stay fuller between meals
Supports heart health by helping lower cholesterol
Provides antioxidants, vitamins, minerals, and other compounds that reduce inflammation, since many high-fiber foods are very nutrient-dense
The challenge for athletes is that the very foods that help us stay healthy can sometimes interfere with training if we eat them at the wrong time.
As Angie and I discuss in the episode, athletes have heard the message loud and clear that lower-fiber carbs are best immediately before training, during races, and while carb loading. But that doesn't mean fiber should disappear from your diet altogether.
"It's really about strategically putting in that fiber when it's not going to have a slowing effect on gut emptying and impaired performance," Angie explains.
If you head out for an early morning run, breakfast beforehand might be lower in fiber. But if you don't have another workout later that day, your recovery meal, lunch, snacks, and dinner are all excellent opportunities to include more fiber-rich foods.
How Much Fiber Do You Need a Day?
Most Americans only eat about 10-15 grams of fiber per day, which is well below the general recommendation of 25 grams for women and 38 grams for men, or 30-40g as I often recommend to my athletes. Getting enough fiber matters, and most people would benefit from eating more of it.
That said, when it comes to fiber for athletes, there's something you have to consider: energy availability. Fiber is very filling, and comes primarily from less caloric foods. This is really important for athletes, who have high energy demands relative to sedentary individuals and would struggle to meet their needs if over-consuming fiber.
What Is "Fibermaxxing"?
That's where the "fibermaxxing" social media trend enters the conversation. It focuses on meeting, or even exceeding, the recommendations above. I love that more people are trying to increase their fiber intake, but you have to be very intentional with how you go about this while also keeping in mind that more fiber is definitely not always better.
For instance, jumping from 10 to 40 grams overnight is a recipe for gas, bloating, constipation, and an unhappy gut. Instead, Angie recommends increasing fiber very gradually while also increasing your fluid intake. Like training for a race, your gut needs time to adapt.
Best High-Fiber Foods for Athletes
We also talked about which foods are the best sources of fiber for athletes. Whole foods like fruits, vegetables, oats, beans, lentils, whole grains, nuts, and seeds should be prioritized. That's because they are naturally rich in fiber, AND deliver carbs, vitamins, minerals, antioxidants, and other nutrients that support overall health and performance.
Some of our favorite high-fiber foods include:
Oats
Beans and lentils
Whole grain breads
Brown rice and quinoa
Berries and dried fruit
Nuts and seeds
Hummus
Fruits and vegetables of all kinds
That doesn't mean fiber supplements or processed foods with added fiber can't be used from time to time, but many products with ingredients like inulin or chicory root can cause unnecessary gas and bloating, especially when eaten in large amounts, so consume with caution.
The biggest takeaway on fiber for athletes? Don't fear fiber, but don’t chase extremes either.
Aim to consistently include fiber-rich foods throughout the day, focusing on whole foods first, while adjusting the amount and timing around key training sessions and races. That's the sweet spot for both performance and long-term health.
Ready to Fuel Smarter?
If you're struggling with GI issues, aren't sure how much fiber is right for you, or want to dial in your nutrition for better performance and recovery, working with a sports dietitian can help you create a plan that's tailored to your body, training, and goals.
Here’s what one client had to say about our work together:
"I worked with Claire to optimize energy and endurance during long days playing beach volleyball. We also worked on gut issues I was experiencing since having 2 kids. Claire is understanding, thorough, professional, and so amazing at what she does. I now know what and when to eat to feel good pre and post workout. No more crashing in the middle of the day and no more migraines. Bloating during workouts is now completely gone. I can't recommend Eat for Endurance enough for all your fueling needs." - Molly B
Here are a few ways we can work together:
Fill out a new client inquiry form for comprehensive 1:1 coaching (limited spots available)
Join my low-cost, low-commitment Fuel for Life Crew membership for just $39/month (cancel anytime)
Browse my nutrition masterclasses (all are also included in the membership)
Grab my Eat for Endurance Mini Guide Bundle (a collection of 6 mini guides, worksheets, and a bonus supplement resource)
No matter where you are in your training, learning how to fuel well today will pay dividends for your health and performance for years to come.
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A big thank you to Tailwind Nutrition for sponsoring this episode!
Use code EATFORENDURANCE20 for 20% off your first purchase at Tailwind Nutrition. I’ve been using their sports nutrition products for years now and I love so many of them! Endurance Fuel has to be one of my favorites and they have tons of yummy flavors.
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Disclaimer: All information provided is for educational and entertainment purposes only and is in no way meant to replace individual medical and nutrition recommendations.
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