Too much fiber - is it a thing? While the majority of people don't consume enough fiber and its benefits, eating too much is possible. A registered dietitian explains how much fiber is too much, potential side effects of too much fiber, and how to relieve the discomforts of excess fiber.
Fiber: What it Is & What it Does
Fiber is an undigestible carbohydrate found in plants. Because it is has some unique properties (it's fermentable!) and it cannot be digested, fiber offers a variety of health benefits, like a lessened risk of:
Fiber can play a role in weight loss and regulation because of fiber's effects on increasing feelings of satiety and fullness.
We also know fiber is good for our gut bacteria and gut health, which positively impacts our overall health, too.
How Much Fiber Do You Need?
Fiber is an essential part of daily dietary needs. The USDA Dietary Guidelines for Americans recommendation is about 14 grams of fiber for every 1000 calories consumed, but vary based on age:
| Age | Daily Fiber Needs |
| Children (1-3 years) | 19 g |
| Children (4-8 years) | 25 g |
| Children (9-13 years) | 26 g (girls), 31 g (boys) |
| Adolescents (14-18 years) | 26 g (girls), 38 g (boys) |
| Adults (18-50 years) | 25 g (women), 38 g (men) |
| Adults (over 50 years) | 21 g (women), 30 g (men) |
How Much Fiber is Too Much?
No upper limit for fiber has been set. NAM, the National Academy of Medicine, (formerly the Institute of Medicine) has suggested there may be a need to establish a tolerable upper intake level in the future - particularly in foods with added fiber.
But one way to know if you're eating too much dietary fiber (or too much too quickly) is if you notice any potential side effects.
Side Effects of Too Much Fiber
While most people don't eat the recommended daily fiber intake, it is possible to eat too much.
Side effects of too much fiber may include:
- Cramping & abdominal pain
- Flatulence (particularly in those with IBS)
- Diarrhea or loose stools
- Constipation
- Lowered blood sugar levels (which can be beneficial, but it's also important to know if you have diabetes)
- Intestinal blockages in individuals with Crohn's disease
- Feeling overly full
- Decreased appetite
Additionally, while it is not currently thought excess fiber could create mineral deficiencies, very high fiber intake could lead to decreased absorption of some minerals.
Often it's not the fiber itself that's the issue, but rather suddenly increasing your fiber intake or heavy use of fiber supplementation that causes some of these side effects, so keep that in mind.
If you’re experiencing nausea, vomiting, a high fever, or a complete inability to pass gas or stool, please call your doctor right away.
Can Excess Fiber Cause Constipation or Diarrhea?
Even though fiber is often recommended as a treatment for constipation, dramatically increasing the amount of fiber in your diet too quickly can lead to gastrointestinal issues - like constipation.
Additionally, despite the fact that fiber can help regulate bowel movements, diarrhea can be a side effect of consuming excess fiber too quickly, especially in folks with digestive disorders (like IBS).
In fact, one study found that particularly amongst those with existing gastrointestinal issues, fiber can sometimes worsen bloating, gassiness, constipation, and diarrhea.
For more information on fiber's role in digestion and how it affects bowel movements, read more in my article on Does Fiber Make You Poop?
What to Do if You're Experiencing Side Effects
If you're experiencing digestive discomfort and other side effects from excess fiber (or too much, too quickly), try this:
- Scale back your current fiber intake and instead, gradually increase your dietary fiber over the course of a few weeks. (This allows the good bacteria that's naturally occurring in your gut to more easily adapt).
- Drink plenty of water! (Fiber works best when it has adequate water to absorb, leading to soft, smooth stools.)
- Pause fiber supplements, at least until you've improved your fiber tolerance (and it may not be a bad idea to run it by your doctor before resuming). But really? You can more than meet your dietary fiber recommendations through food alone (legumes, fruits, vegetables, and whole grains).
- Check ingredient labels for inulin and chicory root extract, and consider avoiding those and other fiber additives until you've increased your fiber tolerance (or altogether, if they don't make you feel your best).
- Go for a walk, or move your body in a way that makes you feel good. But walking counts! A simple walk can still contract your stomach muscles, which helps push out gas and bloating and can help keep you regular.
- Track your fiber intake. You don't have to go crazy with logging every detail you consume in an app, but if you're concerned about your fiber intake you could temporarily try tracking the grams of fiber you're consuming over the course of a few days.
Once the side effects have abated, you can slowly start re-introduce fiber-rich foods into your diet. Gradually increase the daily amount of fiber over the course of a few weeks, and focus on meeting your fiber needs from a variety of sources. Many fruits, vegetables, legumes, whole grains, nuts, and seeds provide dietary fiber.
Final Thoughts
So, is it possible to consume too much fiber? Yes - but often the side effects from eating too much fiber are really more like side effects from suddenly eating too much too quickly (especially if there is any history of gastrointestinal disorders).
If you enjoy learning about fiber, be sure to check out more related fiber articles:
- Does Blending Destroy Fiber & Nutrients?
- The Ultimate Guide to High Fiber Smoothies
- Does Fiber Make You Poop?
Also - if you're ready to actually get a better understanding of nutrition and the science of how your body wants to be fueled, while also learning how you can still eat all your favorite foods, sign up for my waitlist to be the first to hear about my upcoming course and any future coaching opportunities!
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