T Nation

Fiber, Diet and Bile Lipids


Over the years nutrition and diet have undergone a lot of research. I remember the low fat craze from a while back and it can work. I also remember the low carb craze, which isn't over yet, and it can work also.

As the title of this thread might imply, I think that fiber might have a significant impact on our nutritional status. However, don't go and overdose on fibrous foods all of a sudden. Not only will you regret it, getting too much can be unhealthy, just like anything else.

However, the modern western diet is commonly regarded as deficient in fiber. In fact, the high availability of processed carbohydrates is synonymous with the removal of fiber from our carbohydrate sources. I think most of us are aware of the consequences with respect to insulin, but there is also an issue with respect to our digestive tract.

Certain types of fiber are able to bind with bile acids. When this happens, cholesterol and lipids in the bile that is bound in this way are not reabsorbed into the body. This forces the liver to synthesize more bile, which makes use of lipoproteins in the bloodstream.

For example, I'm sure just about everyone has heard that fiber has been proven to help lower cholesterol? Well, to put it simply, this removal of cholesterol in the digestive tract, and hence it's consumption while the liver synthesizes more bile, is how this occurs.

Here is an interesting study (see Appendix table A-2C) which attempts to determine the rate at which bile is secreted from the liver:

Mathematical model of biliary lipid secretion: a quantitative analysis of physiological and biochemical data from man and other species

To make a long story short, they conclude that the amount of bile produced is generally related to body weight, such that we produce approximately 0.22ml/kg/hr. So, at a bodyweight of near 100kg, I should produce about 22ml/hr or 528ml/day. I'll go with 500ml/day for simplicity.

So, if I don't eat any fiber, the body will very efficiently reabsorb almost all the cholesterol and lipids contained in that half litre of bile.

Here is a different interesting study (see table 2) which allows us to get an idea of the amount of lipids contained in the bile of an individual.

High level of deoxycholic acid in human bile does not promote cholesterol gallstone formation

So, unless I'm getting the wrong data, it amounts to be approximately 13g/dl. People with gallstones apparently have lower lipid levels in their bile. Anyhow, if 500ml equates to 5dl, I'm circulating and recirculating a total of approximately 65g of lipids through my digestive tract during the course of a day.

Remember, this is 65g of mostly reused lipids, as it is generally going to be reabsorbed, resynthesized and recirculated again and again during any given day,

While I didn't find anything which tells me how much bile is released in response to a meal (as it may be produced at a fairly constant rate by the liver it is also stored in the gall bladder), the fact that fiber has a dramatic effect on cholesterol let's us know it isn't trivial.

Based on all of this, I'm going to suggest that body composition changes on a controlled diet are going to be easier with appropriate levels of fiber.

Remember, you can get unsafe levels of fiber, so don't simply go crazy with this concept. Also, remember that you need fats for various bodily functions, you can't just stop eating them.

That being said, if your insulin levels are relatively low due to not eating refined carbohyrates, and lipids are being bound to fiber in your digestive tract, you know that your liver is not going to stop producing bile, so you can guess that lipids will be taken out of the bloodstream. With low insulin levels, the fat cells should release more.

This also coincides with the fact that nutritionists are now telling us to consume whole oats, beans, and fibrous fruits and vegetables as our carbohydrate sources. I suspect there is more to this than simply insulin control.


True facts Bro'. I myself have lost significant amounts of body fat by eating between 6 and 10 grams of fiber with three meals a day. I also cut out all simple carb foods. I ate plenty of proteins, both lean and fatty, fruit, and veggies. I also supplemented with flax oil at 1 Tbl per day and multi vitamins. This worked for me but it may have more to do with my endomorphic body type working in synergy with a high fiber low simple carb diet.


Great read Vroom. Ive read before that our anscenstors as little as 100 yrs ago ate a diet that included a whopping 50 grams of fiber a day. Compare that to todays diet with your usual american getting 10 if he is lucky.

I love high fiber meals. A decent meal with a couple pieces of fruit around 10 grams fills me up as if I ate a large protein meal.

It may also be a good idea for someone looking to gain weight to eat large amounts of carb meals low in fiber wouldn't it? They, theoretically, would always be hungry. (Short term of course)


I've heard of this before. VERY good information man. To me,we need just as much, if not more, fiber as we do omega 3's. Maybe thats why I'm really low in body fat, lol. I must eat, atleast,75 grams of fiber a day.

Once again,great post, man.


Whopping 50 grams? Err...I get half that amount just for breakfast: 1c Oats, 2T Flax, 1/3c Grow!, 1oz Almonds, 1oz Coconut & Baby Carrots. It'll fill me up for a good 3 hours.


But where also talking about people that were about half the size of people today and ate much less the amount of food. You got people eating 2000 calories a day if their lucky, and getting in 50 grams of fiber is pretty good.


Whopping 50 grams? Err...I get half that amount just for breakfast: 1c Oats, 2T Flax, 1/3c Grow!, 1oz Almonds, 1oz Coconut & Baby Carrots. It'll fill me up for a good 3 hours.

Keep in mind that there is always a limit to how much of any nutrient or food you should consume. Dietary guidelines suggest an upper limit of 60 grams of dietary fiber per day for adults.

I am sure that excess amounts of fiber in the diet would have some sort of negative effect on the body. I am not sure what they would be but fifty grams of fiber just at breakfast would keep one close to home or atleast make one aware of the location of every public restroom in your vicinity.