T Nation

Fiber

Okay, I’ve tried and tried and tried to understand, but I still don’t get! Dietary Fiber. So I know it counts as a carb in that it has 4 cal/gram, but what about it’s effect on blood sugar levels and insulin release? That is, if you’re low-carbin it for a while, will eating dietary fiber take you out of ketosis? I’ve eaven heard that every gram of fiber you take in blocks like 7 calories or somthing to that effect, but that’s gotta be BS. Someone help please!

Dietary fiber IS a carbohydrate, IF you are an animal that can digest it! We simply can’t, don’t have the correct enzymes, so it passes through our system without yielding any energy. Thats why it makes our gi tract flow so nice as well!

Fiber has zero calories. On food labels, due to USDA rules, fiber is included in the TOTAL CARB GRAMS and sub listed under that as FIBER GRAMS. To get the real (digestable) carb grams, subtract the fiber grams from the total carb grams and multiply the figure by 4 calories per gram to get the corrected calories of digestible carbs. You cann’t digest carbs or burn them for energy and they have zero calories as far as the body is concerned and do not have any effect on ketosis. Just remember to subtract the fiber grams from the total carb grams to get REAL carbs.

Thankee thankee, gents. Appreciate the hlp.

That’s interesting if fiber really does have zero calories. That would basically mean it has negative calories since fiber is kind’ve thick and actually probaby requires quite a bit of energy for the body to digest and eliminate. Anyone else care to comment?

In theory, you could say that fiber itself causes a negative caloric balance, but most people don’t take in that much fiber. A high carb diet might give you 50-60g/day, but still this amount would cause minimal energy deficit. I’d rather stick to exercise to expend my energy. You could also think of ice cold water the same way. If you drink 1 L of ice water (0 degrees celsius), you would have to expend 37 calories to bring it up to body temperature. This is based on the definition of a calorie: the amount of energy needed to raise the temperature of water by 1 degree celsius. This assumes (1 calorie as we talk about them = 1 kilocalorie and the quantity of water is 1 L). Just a thought. There are a lot of these metabolic tricks to burn up a few extra calories.

Fibre has calories and can be utilized by the body, indirectly anyway. Our colonic microflora can digest fibre into gas and short chain fatty acids, these fatty acids are either used by the colonic epithelium or transported via the portal vein to the liver, where it can be used for energy. Sure it isnt very huge source of energy, but it still can provide some energy.

Though you are 100% correct, IMO, there is absolutely no risk that any of the short chain fatty acids formed by fermenting fiber in the colon would ever be stored as body fat - the amount formed is miniscule and as you said - used directly by the colonic epithelium. For all practical purposes, everyone can disregard any caloric value for carbs. They certainly don’t provide caloroies like other carbs or fats or protein.

Correction to my previous post: What said “for all practical purposes, everyone can disregard any caloric value for carbs” - ment to say - " for all practical purposes, everyone can disregard any caloric value for FIBER" - though I wish it was the other way around.