Feeling Gassy and Bloated from Fiber? This Could be Why

Julia Malacoff
Medically Reviewed
July 6, 2021

You’ve probably heard about the health benefits of fiber . It might not be the most exciting nutrient, but it’s a veritable superfood in its own right. It can help balance your hormones , manage your cholesterol , and keep your gut happy . But, does fiber make you gassy?

Yes, fiber is good for you—then why does fiber make you bloated and lead to other stomach troubles? If fiber seems to be a culprit in your digestive issues, don’t quit it all together. Instead, hone in on some of the root causes that could be at play.

According to Marie Carlson, a nurse practitioner formerly with Parsley Health, there are quite a few reasons fiber might leave you feeling either stopped up or way too “loose.”

If you’re dealing with any of the following symptoms after eating more fiber, something could be up:

  • gas
  • bloating
  • feeling uncomfortably full after eating
  • diarrhea
  • constipation
  • belching
  • acid reflux
  • abdominal pain or cramping

Why does fiber make you gassy?

Here are some of the top reasons fiber might leave you feeling less than great.

Eating too much fiber

Across various sources , recommended daily fiber intake varies between 19 to 38 grams of fiber a day, depending on your age and sex. Most groups, from the American Heart Association to the FDA, recommend somewhere in the ballpark of 25 grams a day. “But it looks like going up to about 50 grams a day may be ideal,” Carlson says. That said, there’s definitely such a thing as too much fiber. “If you’re getting up in the range of 50 to 70 grams, that’s where you may start to have more symptoms.”

Increasing fiber intake immediately

This is pretty common, Carlson says. Sometimes, people get excited about switching to a new, whole-food, very high-fiber diet with lots of fruits, vegetables, beans, and so on. “Your digestive system has to adjust to the new fiber intake,” Carlson says.

For this reason, you want to increase your fiber consumption gradually, usually adding about 2 to 3 grams per day, Carlson notes. In real food terms, that could be adding a serving of fruits, vegetables, or whole grains each day . For someone super who finds they’re more sensitive to changes in fiber, Carlson recommends adding one serving every two or three days, based on how you’re responding.

Not drinking enough water

Related to the above, if you start eating a lot more fiber but aren’t getting enough fluids, you can end up with a big blob of fiber hanging out in your intestines, Carlson says. Hello, bloating and gas .

The good news is that if you’re getting much of your fiber from fruits and vegetables, those contain a lot of fluid already. But if you’re loading up on grains, for example, and you realize you’re not getting much in the way of fluids, that could be the culprit behind your discomfort. Also, if you’re taking a fiber supplement , it’s super important to take it with a tall glass of water, Carlson says, as it won’t contain any fluid.

FODMAP sensitivity

FODMAP stands for fermentable oligosaccharides disaccharides monosaccharides and polyols, which are basically types of fiber that are either slowly absorbed or indigestible in our systems,” Carlson explains. FODMAPs are in a lot of foods, but some of the top ones are wheat, milk, cauliflower, onions, apples, and legumes.

“A lot of people who have IBS find relief by going on a low-FODMAP diet ,” Carlson says. So theoretically, if you increase your fiber intake and you have undiagnosed IBS, the increase in FODMAPs along with the extra fiber overall could be making you feel crummy. Trying out a low-FODMAP diet might be a solution here, Carlson says, but she also recommends testing for an overgrowth of bacteria in the small intestine called SIBO . “If you have SIBO , that really needs to be identified and treated before you can tolerate FODMAPs.”

Lectin sensitivity

Lectins are a type of carbohydrate-binding protein , and they’re found in high levels in certain grains, legumes, and nightshade vegetables,” Carlson says. They’re also found in smaller amounts in most types of plant foods. Lectins are kind of a mixed bag. They seem to have some good effects, and some bad ones, according to Carlson. “We need more research on them,” she adds. But some people are particularly sensitive to lectins, so this could be another reason you’re dealing with digestive issues when eating more high-fiber foods, many of which are higher in lectins.

Gut motility issues

Gut motility is what allows digested food to move through your digestive tract. And if your gut isn’t moving things along properly, fiber is likely just sitting there in your intestines, causing bloating and discomfort. “Slow gut motility is really common in people with diabetes, hypothyroidism, and even people with high-stress levels,” Carlson says. IBS and SIBO can also mess with gut motility.

Allergy and/or sensitivity to wheat

“One common recommendation to increase fiber is to add to your whole grain intake, and so many people will just turn to whole wheat products,” Carlson explains. Problem is, wheat is a common trigger of GI symptoms through many pathways: celiac disease, non-celiac gluten sensitivity, FODMAP sensitivity, and lectin sensitivity. So for some people, loading up on more wheat products than usual will send their digestive system into a tailspin.

But don’t ditch fiber

If you’re experiencing symptoms from eating fiber, there are a lot of good reasons not to give up on the nutrient completely.

“Fiber generally promotes digestive health and helps balance blood sugar and cholesterol levels,” Carlson says. “And it’s actually the primary food source for the trillions of microorganisms that are living in our intestines, known as our microbiome.” Good fiber intake has also been shown to reduce the risk of colon cancer . And one study showed that increasing fiber intake, especially coming from cereals and vegetables, by 10 grams a day reduces the overall risk of death from all causes.

For many people, reaping the health benefits of fiber comes down to putting in the effort to narrow down which sources work for you.

How to determine the right fiber intake

Get fiber from whole food sources

When possible, opt for whole foods over fiber supplements to avoid symptoms, Carlson recommends. Ideally, you want to mix it up with your sources, too. “I tend to steer people towards nuts, seeds, fruits, veggies, beans, and legumes,” she says.

Choose the right supplements

If you suspect FODMAPs or lectins might be an issue, you may need to go for a fiber supplement while you get that figured out. If that’s the case, Carlson recommends acacia, psyllium husk, or sun fiber supplements. It’s best to work with a provider to determine the right dose for you and help you to monitor your symptoms.

Give yourself enough time between meals

To allow for optimal gut motility, Carlson suggests a 12-hour fast overnight (so, from 8 p.m. to 8 a.m., for example) and allowing about three to four hours between each meal.

At Parsley Health , members work with a health coach to help them optimize their diet and lifestyle. Having the support of a coach can be a gamechanger for adjusting your nutrition to relieve digestive symptoms. If you’ve increased fiber gradually, are following the guidance above, and are still having symptoms, that’s a sign to check in with your health care provider for further evaluation and testing.

Julia Malacoff

Julia Malacoff is an Amsterdam-based freelance writer, editor, and certified personal trainer. She covers a wide range of wellness topics including nutrition, fitness, specific health conditions, and the latest scientific research in these field. Julia graduated from Wellesley College and she works with brands like Shape, Cosmopolitan, Fast Company, Precision Nutrition, Equinox, and Aveeno. Outside of work, you can find her walking her dog, trying out a new recipe, or learning Dutch.

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