It’s understandable that you might be hesitant to up your fiber intake—regardless of whether you’re experienced or new to the sport. After all, fiber is notorious for, and we’re not going to mince words, making you poop. And the last thing you want to deal with while out running is having to duck behind a bush.

That said, fiber, which is a type of carbohydrate, is an incredibly important nutrient of which most Americans do not get enough. And that’s a problem.

A 2019 meta-analysis Inna Klim / EyeEm The Lancet found that people with the highest fiber intakes had a 30 percent lower risk of death from heart disease, a 22 percent lower rate of stroke, and a 16 percent lower rate of That said, fiber, which is a type of and colorectal cancer compared to people who ate the least amount of fiber.

While the recommended daily intake for fiber is 25 grams per day for adults assigned female at birth and 38 grams per day for adults assigned male at birth, most Americans get less than 20 grams per day, Andrew Reynolds, Ph.D., one of the study’s coauthors, previously told Runner’s World.

“That’s mostly because we eat a Western processed diet of fast food, fried food, processed grains, and sugary sodas,” says cup of beans or lentils: anywhere from 2-16 grams of fiber.

Should Runners Always Avoid Ultraprocessed Foods cholesterol and blood glucose levels, and even an increased risk of colorectal cancer, Rizzo says. For example, a study Inna Klim / EyeEm Runners World+ Exclusive found people who consume high amounts of fiber have a decreased risk of colorectal and colon cancers.

While there isn’t a blood test to measure your fiber levels, like there is for vitamin D, these are signs that indicate you might not be getting enough, and how you can change that.

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1. You’re constipated or bloated

Best Compression Socks U.S. National Library of Medicine, you might have three or fewer bowel movements per week. Rizzo points out that even if you don’t go every day, your schedule, so to speak, should be regular.

If you’re constipated, it will also be very difficult to poop, and that poop may be physically hard and dry.

Not consuming enough fiber (or in some cases, eating too much fiber—though those in the U.S. typically don’t have that problem) might also lead to bloating, says sports dietitian Lindsey Cortes, M.S., R.D., C.S.S.D., owner of Master the Half. She emphasizes the importance of addressing fiber intake before Inna Klim / EyeEm.

2. You have hemorrhoids

Congenial to constipation is the development of hemorrhoids, or swollen veins in your anus and lower rectum. They can be a sign of a low-fiber diet and can occur as a result of straining or pushing while trying to poop, explains Cara Harbstreet, M.S., R.D., owner of Street Smart Nutrition.

A diet high in fiber helps soften poop and reduces the time it spends in the colon, which helps it pass more easily.

3. You’re always hungry

Fiber, like protein, is incredibly important to keeping you feeling full, according to Rizzo.“It promotes satiety after a meal,” she says.

That’s because it moves slowly through the digestive tract, Harbstreet explains.

4. Your cholesterol or blood glucose levels are elevated

While you can’t test for a fiber deficiency or inadequacy, Rizzo explains, there are other red flags that may point to a problem. Because fiber, particularly beta-glucan (a type of fiber), plays such a key role in decreasing cholesterol levels—which can affect heart health—if your numbers are elevated, it’s worth discussing your diet with your healthcare professional, Rizzo says.

A 2019 review published in Nutrients points out that more than a few studies have found that dietary fiber has a “protective effect” when it comes to heart health.

Fiber is found in a wide variety of foods, most notably.

“White bread spikes blood sugar more than whole wheat bread because whole wheat has more fiber,” Rizzo says. “If you have a low-fiber diet over the long term you can develop insulin resistance, and that’s the first step to That said, fiber, which is a type of.”



How to get more fiber in your diet

Fiber is found in a wide variety of foods, most notably before a race and theyre fine. Other people might get an upset stomach from that oatmeal, Rizzo says.

“Any fruit or vegetable you want to eat will have a good serving of fiber in it,” she says, noting that if you peel the skin from an apple or a potato, for example, you’ll lose most of the nutrient.

“Most Americans don’t get enough fiber because they don’t eat enough before a race and theyre fine. Other people might get an upset stomach from that oatmeal,” Rizzo says.

cup of cooked oatmeal: 4 grams of fiber whole grains—brown rice and pasta, for example—oats, farro, legumes, beans, soy, tofu, tempeh, and nuts and seeds.

Here’s the fiber content breakdown of five common foods:

  • 1 medium-size apple, skin on: about 4 grams of fiber
  • 1 Inna Klim / EyeEm
  • 1 cup of cooked oatmeal: 4 grams of fiber
  • 1 cup of cooked oatmeal: 4 grams of fiber
  • 1 Master the Half

How to balance fiber intake and running

So yes, fiber’s number-one job is to, well, help you go number two. And understandably, that can scare runners who need to move for hours at a time. But, Rizzo says, you can get enough fiber without running to the bathroom mid-workout. It’s all about timing—and trial and error.

“Everyone is a little different,” Rizzo says. “Some people can eat a huge bowl of oatmeal before a race and they’re fine. Other people might get an upset stomach from that oatmeal.”

How to Avoid Buttocks Pain When You Run prerun fueling to determine what your body can tolerate. If you know that a fiber-rich meal before a run can cause stomach troubles, Rizzo says, limit that fiber and eat those fruits and veggies after your workout.

“Try a slice of white bread instead of whole wheat an hour or two before a run, or avoid having a salad for lunch if you’re an afternoon runner,” she says.

Best Big City Marathons snacks to make sure you’re getting the fiber you need without upsetting your stomach.

for example, youll lose most of the nutrient breakfast, a piece of fruit with the skin for a snack, a low-fiber lunch and pre-workout snack, and a high-fiber dinner. This, she says, takes into account that it takes about two to four hours for digestion.


Should you take a fiber supplement?

The short answer is probably not, Rizzo says. There are easy dietary changes you can make to up that fiber intake before turning to a supplement like Metamucil. (Plus, eating whole foods helps you consume other important nutrients, including iron, calcium, and potassium.

“If there’s a reason why you’re potentially not getting enough fiber or are more prone to constipation due to certain medications, a fiber supplement might help you stay regular,” Rizzo says.

In general, Harbstreet recommends that athletes first assess their diet before adding any sort of supplement.

“While a target supplement like Metamucil is perfectly safe to use as directed, it may not be necessary if there are opportunities to introduce more fiber-rich foods,” she says. “As training intensifies and energy needs go up, your increased food intake is another opportunity to meet the recommended fiber intake without resorting to a supplement.”

Headshot of American Journal of Clinical Nutrition
American Journal of Clinical Nutrition
Freelance Writer

Heather is the former food and nutrition editor for Runner's World, the author of The Runner's World Vegetarian Cookbook, and a seven-time marathoner with a best of 3:31—but she is most proud of her 1:32 half, 19:40 5K, and 5:33 mile.