Can You Eat Too Much Fiber?

by Charlotte on November 27, 2010 · 1 comment

When it comes to eating disorders I often have a been-there-done-that-bought-the-t-shirt attitude. What I forget is that despite being around since at least the Greeks, these pernicious disorders are constantly evolving to take advantage of current trends and products. So it was with some surprise I read an e-mail from a brave and beautiful reader. She writes:

I’ve recently been taking fiber powder as a laxative, and I suppose taking an excess amount (a cup and a half some days, and a serving is two spoonfulls). It’s weird – I always said I would never take laxatives because it’s not “real” weight loss, yet I’m taking insane amounts of fiber (though in my head that’s not a laxative, just has a laxative effect). A friend mentioned that excess fiber can actually cause bloating, and too much can have the reverse effect if you don’t drink enough water… I don’t know if you have any experience with this or have read anything about this in all your research, but if you have any thoughts about it or ways to make it go away.

Can You Have Too Much Fiber?
The Harvard School of Public Health recommends 20-25 grams of fiber a day for women and 30-35 grams for men. However, they don’t really set an upper limit. For most of history getting too much roughage in one’s diet was not really a problem. In fact, most Americans get far less than the recommended daily amount. People eating real food find that fiber ends up being self-limiting. Sure lentils pack a whopping 16 grams of fiber per cup but anyone who has eaten an entire cup of lentils can tell you how that feels – after they return from multiple trips to the bathroom, that is. But in this day of Metamucil, Benefiber, and fiber-fortified cereals, granola bars, pop tarts, waters and even soups, people who trend towards the more-is-always-better school of thought can easily overdose on the stuff.

Fiber is a tricky thing. Too little and you end up being constipated – as all those strangely invasive commercials will tell you – not to mention that fiber helps with heart health, reduces diabetes and helps with irritable bowel symptoms among other things. But can you have too much fiber?

Excess fiber, generally defined as greater than 50 grams per day, has several well-documented effects. Besides the gastronomical effects (everything from explosive diarrhea, gas, and cramping), it can lead to vitamin deficiencies as it interferes with their absorption. Not to mention the excess bloating mentioned by the writer of the e-mail.

Using Fiber To Purge
The part of the e-mail that really caught my eye though was using fiber as a purging technique. (Dear Reader, you are beautiful and strong and purging in any form will wreck your body and your mind. Please, please seek out qualified help for disordered eating before you get more ensnared!) Bulimics have long used emetics, laxatives, diuretics, exercise and even feeding tubes as ways of purging food from their systems. But taking a cup and a half of fiber powder – the equivalent of 90 grams of fiber – to achieve the laxative effect is one I’d never heard of before.

After thinking about it though, I can certainly see where the temptation lies. I remember one day both Gym Buddy Allison and I O.D.’ed on fiber powder – you should have heard (and smelled) that conversation at the gym; we both added it to chili! – and both of us did it out of a desire to use fiber to control our weight. The problem is that everywhere you look, fiber is the new “it” word for weight loss. Fiber “fills you up” and “triggers satiety” and even, as evidenced by Fiber Choice’s Weight Management tablets, help you “control your weight.”

I’ve bought into that marketing mania. If I have a choice between buying a regular granola bar or a “fiber bar”, I pick the fiber bar every time. Which isn’t necessarily a bad thing. Except that all the extra fiber adds up and now my body is used to a lot of fiber and needs it to, you know, keep things moving. It’s funny how these things sneak up on you. Everything I’ve read says that if you eat a wide variety of fruits, vegetables and whole grains you’ll get all the fiber you need from your diet. So why the huge boom in fiber-enhanced products? I’m guessing it’s for the money. Either that or some ConAgra CEO finds sharts funny.

What’s your take on fiber: do you only get it from whole-foods sources or do you love a little benefiber sprinkled on your oatmeal? Do you buy fiber-fortified products?


If you’ve never seen this Sarah Haskins video before, it’s an oldie but a goodie! Warning: use the potty first if you have a weak bladder.

Written with love by Charlotte Hilton Andersen for The Great Fitness Experiment (c) 2010. Thanks for reading!

{ 1 comment… read it below or add one }

Abby January 9, 2013 at 4:12 am

Great post!

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