When a type of food or wellness trend becomes largely understood as “healthy,” many of us assume that more of it is always beneficial, without limit. This “more is better” mentality spreads on social media, where the spectacle of “maxxing” out gets clicks, while the old-school approach of strategic moderation gets scrolled right by.
It’s led to trends like proteinmaxxing, sleepmaxxing, and more recently, fibermaxxing, where people tout their super-high fiber intake in the name of disease prevention, digestion, and gut health.
Fiber is one of the healthiest things Americans underconsume. But that doesn’t mean piling on more and more will keep delivering bigger returns. Experts say the goal is not to max out, but to find the amount—and sources—that work best for your body.
The fiber gap is real
Fiber intake in the U.S. remains abysmally low. The average person eats 10 to15 grams per day, well below the recommended 25 grams for women and 38 grams for men. That shortfall is a problem because fiber is essential to good health.
Fiber is found mostly in plant foods. It’s capable of journeying through the small intestine to the large intestine, where it promotes health. One main fiber type is soluble, which dissolves in water and can form a gel-like substance. Soluble fiber is linked to benefits like healthier cholesterol, blood-sugar, and gut microbes. Another type is insoluble; it doesn’t dissolve, adds bulk to stool, and supports regular bowel movements.
Many soluble and insoluble fibers are fermentable—they break down into compounds such as short-chain fatty acids that may lower inflammation.
These distinctions are useful to understand fiber’s benefits, but practically speaking, any whole plant food will offer a mix of soluble and insoluble fibers, packing all of the related health payoffs.
How to optimize your fiber intake
Some social-media enthusiasts boast about fibermaxxing by posting a day’s worth of 70-80 grams, more than double the recommended amount.
“Maxxing can be a bad idea for many people,” says Sara Rosenkranz, professor of nutrition science and kinesiology at the University of Nevada Las Vegas. “Optimization is what we really want, where we’re getting adequate fiber along with other nutrients.” But the fibermaxxing trend could help low-fiber eaters if it motivates them to have more, since most people get so little, Rosenkranz says. The optimal fiber intake also depends on how much you eat overall; the recommendation is 14 grams per 1,000 calories.
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A large research review in the Lancet found lower risks for dying earlier and getting chronic diseases as fiber consumption increased, though the biggest gains occurred by raising intake to 25-29 grams. Above this amount, additional benefits still accrued but became smaller.
A research trial in 2023 tested a “microbiome enhancer diet” with resistant starches, no ultraprocessed food, and about 50 grams of fiber per day (depending on overall calories). Grant reviewers were concerned about the side effects of so much fiber, says Rosa Krajmalnik-Brown, a study author and engineer who directs Arizona State’s Biodesign Center for Health Through Microbiomes. But participants had no issues and their microbiomes were healthier, compared to people on a low-fiber diet. Their microbes harvested calories more efficiently, which counters weight gain.
“I would recommend the microbiome enhancer diet to any healthy person without gastrointestinal issues,” Krajmalnik-Brown says, whereas people with GI issues should follow their doctor’s guidance.
This year, a large review found that people who consumed more fiber had better digestive health. Each additional gram per day—up to 75 grams—was linked to bulkier stool and more frequent bowel movements. However, data on intake over 50 grams was limited, since it’s hard to get people to eat that much fiber.
Dr. Sean Spencer, a gastroenterologist and physician scientist at Stanford University, says that getting 30-40 grams is great, “and if you can get to 50 or 60, that’s even better. Those are very safe amounts.” Going higher is more personalized. “It’s what your microbiome can handle, and how you feel when you’re doing it,” Spencer says.
But the source of fiber matters
It’s tough to tally up your daily grams of fiber, and other measures may be more useful anyway. “The better approach is to count plant-based foods like vegetables and fruits,” Spencer says. He and others recommends aiming for about 30 types of whole foods per week.
That reinforces the value of eating real food—a point overlooked by some gram-focused fibermaxxers. The body is not a machine to be hacked; it’s an ecosystem to be tended. Lower-quality fiber, attained through supplements or ultra-processed foods with fiber additives like inulin and fructooligosaccharides (FOS), provides fewer ecosystem benefits, even if they boost your fiber stats.
“If you asked AI to design the perfect fiber supplement, optimized for blood sugar control and nutrition, it would probably come up with a raspberry, apple, or avocado,” Spencer says. These fiber-rich foods also provide key phytonutrients, including polyphenols with strong microbiome-boosting effects.
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Psyllium may be an exception to the no-supplement rule. Technically, this plant husk, ground into a powder, is a supplement, but it’s loaded with fiber (mainly the gel-forming, soluble variety). In a diet otherwise full of whole foods, it can help digestion and constipation, weight loss, cholesterol-lowering, and healthier blood glucose.
Don’t ramp up too fast
Even with whole foods, you’ll want to increase fiber gradually. “It’s great if someone is increasing their fiber,” says Yasi Ansari, a registered dietitian. “But let’s make sure we’re being strategic.”
Increase daily fiber by 5 grams each week, Ansari recommends. Many additions can get you there. She suggests adding a plain greek yogurt, topped with a tablespoon of flaxseed and a half-cup of berries, as a snack. Or a half-cup of edamame.
“Just try to be consistent with fiber and make sure you’re including it in meals throughout the day,” Ansari says.
Rosenkranz notes that having lots of fiber may come with an opportunity cost, where you can’t fit in as many foods with other important nutrition like protein—partly because fiber promotes feelings of fullness. “Too much of one thing can crowd out the nutrients you need from something else,” she says. Look for foods that combine fiber with healthy proteins, carbs, and fats. Spencer’s favorites are chia seeds and avocados.
Don’t go overboard at once with these examples. Sudden increases can lead to gas, bloating, and general discomfort. Make sure to stay hydrated while ramping up. Psyllium in particular can cause these side effects, and there’s a risk, albeit a small one, of intestinal blockage if it’s consumed without enough water, Rosenkranz says.
When increasing fiber, be cautious about having it right before a heavy workout, Rosenkranz says, since post-fiber exercise can cause GI discomfort.
Find what works for you
Fiber, perhaps even more than other nutrients, is highly individual. One reason is that gut microbes vary widely. In Krajmalnik-Brown’s study, the amount of energy harvested from the high-fiber diet differed considerably across participants.
Having more than 60 grams per day works well for some but not others, so you’ll want to monitor your bowel movements. “I’d be really worried about diarrhea,” Krajmalnik-Brown says. If high fiber is causing diarrhea, that alters the gut microbe population too quickly. “Faster growing microbes are the only ones that will thrive, as the others are washed out,” Krajmalnik-Brown explains, potentially favoring less beneficial microbes.
Another difference is psychological: don’t get caught up in fibermaxxing on social media if you feel more pressured than excited, says Rosenkranz, who also studies behavioral motivation in health. Some people are encouraged by lofty, ambitious goals, whereas others prefer smaller, more attainable ones.
“Fibermaxxing does provide a clear target, which may be anxiety-reducing in some forms,” Rosenkranz explains. “The real question is, where is that sweet spot for you? What can you accomplish, and how sustainable is it?”