After drastically increasing my fiber intake for nearly a month at the suggestion of family members via breads, fruits, vegetables, and juices, I ran into constipation so severe that I was unable to have a bowel movement for two weeks because of impacted stool. As it got worse, I began consuming even more fiber at the recommendation of my doctors. No amount of laxatives or suppositories could initiate a bowel movement, and my abdomen was becoming so bloated that I could not even move at all for several days without excruciating pain.

This led me to do some research about just how healthy fiber really is. After having the stool de-impacted by the doctor, I returned to my previous diet which consists mainly of white rice, meat, and vegetables (I am lactose intolerant and take vitamin supplements) and the stool is coming out so easily I barely even notice it. But this low-fiber diet is causing my family members grief as they think I am going to drop dead unless I return to eating copious amounts of fiber.

I ran across this book while doing some research: Fiber Menace by Konstantin Monastyrsky and was surprised. Every suggestion he had in his book and on his website were contrary to what the doctors and people in general were telling me constantly - eat more and more fiber, more fruits, vegetables, whole grains, and juices, and consume huge amounts of water, otherwise you are going to die.

I guess it's obvious from my little near-death experience now that having too much fiber is bad, but does anyone have any clue as to the scientific validity of Mr. Monastyrsky's book and website? After searching the web for hours I could not find even a single piece of information that even attempted to criticize or argue against his claims other than one three-star customer review on Amazon.com.

Although I remain skeptical of his extreme "absolutely no fiber diet", following his suggestions and reducing fiber intake to only a few spoonfuls of vegetables per meal have definitely returned my bowel movements, health, and happiness back to normal. I want to find out if there's any truth to his claims or if it's just pseudoscience, especially since it seems to contradict general ideas about fiber and doctor recommendations.

  • One comment about fiber and diet in general - if you believe the Primal and Paleo diets are good (as I do, see this answer for many links), then it's not simply fiber that's a problem, but the type of fiber. In particular, grains (and legumes) are considered problematic for many reasons. Vegetables are much better, and actually have much less total fiber than grains/legumes (especially when the grains are concentrated into high-fiber cereals).
    – John C
    Commented Feb 18, 2012 at 13:26
  • Maybe you shouldn't go from 0 to 100 with fiber. Your entire digestive system needs to make a switch...
    – Lagerbaer
    Commented Feb 19, 2012 at 5:42
  • Hi @Lotus Notes, you're question is unrelated to exercise and as we're discussing on Meta doesn't really fit our Q&A format. It would be more constructive to ask for a specific explanation, which in the case of this book would be off-topic given that the questions are unrelated to exercise
    – Ivo Flipse
    Commented Feb 24, 2012 at 14:18

2 Answers 2


You are right, the reaction to this book from the scientific community has been a complete silence. I would not call it pseudoscience though; there were scientific studies showing negative effects of high fiber diets for people with pancreatic insufficiency and certain metabolism deficiencies. Too much fiber could increase malabsorption, impair the absorption of wheat starch in healthy people too. But really depends on the type of fiber - soluble, insoluble, fermentable, resistant starch type 4, etc.

We got interesting preliminary results with Aurametrix, but for now I am only citing a few older studies published in peer reviewed literature:


Fiber is, by definition, indigestible carbohydrate. It either gets processed by the bacteria in your colon or it goes on to the exit. If your gut flora uses it, the "good" bacteria will produce some vitamins and short-chain fatty acids from it (which you metabolize and are good for you) plus some toxins, and the "bad" bacteria will just create toxins.

Insoluble fiber (e.g. grains) will scratch the insides of your gut. Personally, I avoid it.

Cows are mammals that are masters at handling fiber. Their natural diet gives them, after fermentation, almost 70% from energy as short-chain fats. Gorillas have a really big hindgut and also get most of their energy through fermentation.

We humans lack the three stomachs and/or very long gut and therefore can't handle as much fiber. Furthermore there are several examples of populations that eat no fiber at all and nevertheless are healthy (like the Masai and Inuit).

So in conclusion, fiber gives bulk to your stool as well as giving you some extra energy as fat and if you're eating too much of it, inflammation. It is not something to avoid, and not something to seek out. Bloating and gas probably means that your gut flora is having a field day at your expense.

Not the answer you're looking for? Browse other questions tagged or ask your own question.