Published July 6, 2026 01:07PM<\/p>\n<\/div>\n This article has been medically reviewed by Rachel MacPherson<\/a>.<\/strong><\/em><\/p>\n <\/section>\n As runners, hikers, climbers, and cyclists try to optimize their performance in every way possible, they\u2019re turning to a new obsession: fibermaxxing. People on social media promote it as a nutrition hack. The goal? Increasing your fiber intake for better microbiome health.<\/p>\n Consuming enough fiber typically means eating more fruits, vegetables, legumes, and whole grains. These foods also provide important vitamins, minerals, and phytonutrients (substances like carotenoids that plants naturally produce and protect the body against disease), which your body needs to train consistently and recover well.<\/p>\n Certain fibers are fermented in the gut and converted into short-chain fatty acids that support the gut barrier and help regulate inflammation<\/a>. \u201cShort-chain fatty acids are a catch-all: energy source, anti-inflammatory, and reinforcement for the gut lining,\u201d Savita Srivastava<\/a>, a Virginia-based gastroenterologist, tells Outside.<\/em>\u00a0\u201cThey are the unsung heroes in gut health.\u201d<\/p>\n But how might an increase in fiber intake affect overall athletic performance? We asked sports nutritionists and gastroenterologists for their thoughts on the fibermaxxing trend to find out if it can make you a better athlete or just throw a wrench in your digestive system when you\u2019re chasing a new PR.<\/p>\n It turns out the answer to this question is nuanced. Fiber has numerous health benefits, including lowered blood sugar, improved gut and heart health, and satiety. \u201cFiber aids in digestive regularity, reducing constipation, and also supports the gut microbiome,\u201d Kelly Jones<\/a>, a registered dietitian who specializes in sports and performance nutrition, tells Outside<\/em>.<\/p>\n So consuming enough fiber is important. Yet close to 95 percent of American adults fall short of their daily fiber need. Most adults benefit from at least 30 grams of fiber per day (that\u2019s like<\/a> eating two cups of blueberries, an apple, one cup of raspberries, one medium sweet potato, and two slices of whole grain bread in one day) but athletes with high calorie needs can often tolerate or even benefit from more,\u00a0Kaytee Hadley<\/a>, a registered dietitian who specializes in gut health, tells Outside<\/em>. More specifically, women should aim for 25\u201328 grams of fiber per day; men should aim for 28\u201334 grams of fiber per day, according to the Academy of Nutrition and Dietetics<\/a>.<\/p>\n Regarding fiber\u2019s direct impact on performance, things get more complicated. \u201cSince a healthy digestive tract supports metabolism, healthy inflammatory responses, and production of certain nutrients, fiber and whole plant food intake may indirectly benefit how athletes feel and recover,\u201d Jones says.<\/p>\n But eating more fiber today won\u2019t make you run faster or lift heavier tomorrow, Hadley says. While the concept of fibermaxxing generally implies that more<\/i> fiber is better, this isn\u2019t necessarily the case with athletes. If anything, athletes might need to be more careful than most about how much fiber they eat and when.<\/p>\n \u201cI\u2019d caution against fibermaxxing around training times,\u201d Hadley says. \u201cThis is especially important for endurance athletes and anyone with underlying gastrointestinal (GI) issues.\u201d<\/p>\n Consuming too much fiber, more than 50 grams in one day<\/a>, especially before working out, can leave you feeling bloated, crampy, gassy, or urgently needing to use the bathroom. When you exercise for prolonged periods or at high intensity, blood flow shifts away from the digestive tract, which leads to leaky gut, which occurs when bacteria enter the bloodstream, which triggers an immune response leading to inflammation. Over time, inflammation can reduce performance, impede recovery, and shorten longevity<\/a>. (Chronic inflammation is linked to a number of diseases including cancer, heart disease, and diabetes, all of which impact lifespan.)<\/p>\n Dr. Ekta Gupta<\/a>, a gastroenterologist and associate chief for the division of gastroenterology at the University of Maryland, recommends sticking to low-fiber, easily digestible foods several hours before high-intensity exercise.<\/p>\n For instance, according to the National Academy of Sports Medicine, plan to eat between two and four hours<\/a> before your workout and focus on consuming carbs (for energy) and some protein (which can promote muscle protein synthesis<\/a>, especially if you\u2019re planning on doing resistance training); a bagel and nonfat plain Greek yogurt is a great option. You can also opt for an energy bar if that\u2019s what you have on hand. Other low-fiber options include: bananas, applesauce, fish, and eggs. If you need a quick boost ahead of your workout or are feeling hungry, have a light snack such as a banana or carrots with hummus about two to three hours before working out, or go for something extra light such as toast and honey about 30 to 60 minutes<\/a> before working out.<\/p>\n After exercise, especially high-intensity workouts, opt for lower-fiber foods, such as those listed above, if your goal is to refuel quickly. If your goal is muscle growth, choose protein-rich foods and eat them within 45 minutes after working out<\/a>. If your goal is recovery, you can reintroduce fiber-rich plant foods (such as split peas, barley, black beans, and lentils) as part of a balanced recovery meal, alongside carbohydrates, protein, and adequate hydration, about 2 to 3 hours after<\/a> your workout.<\/p>\n Some people tolerate fiber better than others. Determining how much fiber is right for you\u2014enough to support your health but not so much that you\u2019re experiencing digestive distress\u2014may require a bit of trial and error or help from a dietitian. But according to Hadley, at the end of the day, athletes don\u2019t need to fibermaxx; they just need to eat enough fiber to support their gut health.<\/p>\n About the medical reviewer<\/strong>: Rachel MacPherson is a certified strength and conditioning specialist, an ACE-certified personal trainer, and a PN1-certified nutrition coach. MacPherson has spent over a decade helping lifters trade bro science for actual results. She\u2019s happily turned an obsession with evidence-based health into a full-time writing and strategy career, helping publications, wellness brands, and supplement companies tell smarter stories that people trust. She\u2019s a stickler for science-backed training advice that respects the reader\u2019s intelligence, with the ultimate goal of getting you under the bar with total confidence (or moving in whatever way feels best).<\/em><\/p>\n Want more\u00a0<\/b>Outside<\/i><\/b>\u00a0health stories?\u00a0<\/b>Sign up for the Bodywork newsletter<\/b><\/a>.<\/b><\/p>\nKey Takeaways:<\/h3>\n
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The Benefits of Fiber for Athletes (and Why More Isn\u2019t Always Better)<\/h2>\n
How Excess Fiber Triggers GI Distress During Training\u2014and What to Eat Instead<\/h2>\n
How Much Fiber Should You Eat Before Working Out?<\/h3>\n
How Much Fiber Should You Eat After Working Out?<\/h3>\n