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Are Calories from non-paleo foods like Grains fully Digested?

Answered on August 19, 2014
Created February 12, 2013 at 3:02 PM

I've been wondering lately about 'bad' calories from non-paleo foods, how much they are actually digested, and how much of the calories ultimately get into our system. As an example if you ate X amount of bad calories of some sort of wheat product, let's say a bowl of cereal as an example, is your body actually digesting and absorbing the calories or are a large portion of them just passing through you since we are not 'made' to consume them, (already) irritated gut concerns, etc.?

Anyone know of any good books, websites, or references discussing this?

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on February 13, 2013
at 01:03 AM

Corn, despite looking undigested, is digested.

Ebb10603524dd22621c1155dd7ddf106

(19150)

on February 12, 2013
at 08:11 PM

@Lazza I should have spoken clearer, but you are incorrect: they are indigestable *directly* by humans, but they are still digested within the gut, by helpful bacteria. Some are not digested, and this can be because they were "bad", or because the individual's gut bio isn't healthy. Some insoluble fibers are horrendous for IBS sufferers; however, some soluble fibers and resistant starch can be helpful for those with IBS, colitis, etc. Long story short: not all fiber is the same, so don't treat it as such.

Ebb10603524dd22621c1155dd7ddf106

(19150)

on February 12, 2013
at 08:02 PM

Yes! This is actually called *resisitant starch* ( http://en.wikipedia.org/wiki/Resistant_starch ) and is found not just in SAD foods, but in the most paleo of paleo-rific foods: cooked potatoes, sweet potatoes, taro, cassava, squash, other ground veggies - basically anything with some starch. It is considered a fiber, basically. It also feeds gut bacteria, which feed us. So, it isn't quite fair to say that "it gives us no calories", we just get calories from gut fermentation, not primary human digestion.

75d65450b6ff0be7b969fb321f1200ac

(2506)

on February 12, 2013
at 07:46 PM

I believe "indigestable-to-humans" fibers are a leading cause of IBS and leaky gut, as explained in Elaine Gottschall's book 'Breaking The Vicious Cycle'.

Medium avatar

(10611)

on February 12, 2013
at 07:10 PM

The same thing applies to a lot of uncooked vegetables. Raw carrots have a much lower glycemic index than cooked carrots.

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6 Answers

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1
A2c38be4c54c91a15071f82f14cac0b3

(12682)

on February 12, 2013
at 07:51 PM

Short answer; no. Here are some studies:

"After ingestion of bread made from 100g of wheat flour increases in H2 excretion occurred in all subjects; the calculated fractions of unabsorbed starch ranged from 4% to 17% (median, 8%)".

http://informahealthcare.com/doi/abs/10.3109/00365528909092246

"we conclude that most complex carbohydrates, with the exception of rice, contain a good deal of fermentable material that escapes small bowel absorption and it seems likely that this fermentable material is malabsorbed starch".

http://europepmc.org/abstract/MED/3792775

"The results of a series of studies of the digestion of starch from potato and banana are reported...In feeding experiments with healthy volunteers none of the starch was recoverable in faeces, indicating its complete fermentation in the colon".

http://www.nrcresearchpress.com/doi/abs/10.1139/y91-018#.URqaeK4weVs

"healthy volunteers took test meals of white bread made from either regular or gluten-free flour. After bread made from gluten-free flour, the blood-glucose rise was significantly greater. This corresponded with a significantly more rapid rate of digestion in vitro and reduced starch malabsorption in vivo as judged by breath-H2 measurements".

http://ajcn.nutrition.org/content/45/5/946.short

So it does appear a decent amount of starch calories from so called non-plaeo foods are not absorbed (same with some paleo foods as well, though perhaps less so). I would be cautious before assuming this says anything good or bad about these foods. It probably depends in large part on your individual gut bacteria and what effect this malabsorbed starch will have on them.

Ebb10603524dd22621c1155dd7ddf106

(19150)

on February 12, 2013
at 08:02 PM

Yes! This is actually called *resisitant starch* ( http://en.wikipedia.org/wiki/Resistant_starch ) and is found not just in SAD foods, but in the most paleo of paleo-rific foods: cooked potatoes, sweet potatoes, taro, cassava, squash, other ground veggies - basically anything with some starch. It is considered a fiber, basically. It also feeds gut bacteria, which feed us. So, it isn't quite fair to say that "it gives us no calories", we just get calories from gut fermentation, not primary human digestion.

2
Ebb10603524dd22621c1155dd7ddf106

(19150)

on February 12, 2013
at 03:25 PM

I understand what you asked, but the question doesn't make 100% sense as stated.

There is a divide between food and nutrients. We eat food, not nutrients. Food is digested by the body, and the byproducts of digestion, i.e. nutrients, are provided to the body. Amid all the nutrients are macro-nutrients, which colloquially are directly "burnable" by the body.

So, if if the food eaten contains macronutrients in digested form, and those macronutrients enter the body, then yes, those calories are 100% available to be "burned."

However, there's tons of ways that a food's nutrient byproducts can be encouraged to be absorbed, unencouraged, or even "burned" in other ways. One big changer is from fibrous foods. For e.g., fibrous foods will lower overall nutrient absorption (including macronutrients, and therefore calories). But the actual indigestable-to-humans fibers of fibrous foods are fermented by gut bacteria, providing an amount of the macronutrient fat to the body.

The only paleo-sphere book that address this directly, to my knowledge, is "The Perfect Health Diet" by Jaminet/Jaminet.

Ebb10603524dd22621c1155dd7ddf106

(19150)

on February 12, 2013
at 08:11 PM

@Lazza I should have spoken clearer, but you are incorrect: they are indigestable *directly* by humans, but they are still digested within the gut, by helpful bacteria. Some are not digested, and this can be because they were "bad", or because the individual's gut bio isn't healthy. Some insoluble fibers are horrendous for IBS sufferers; however, some soluble fibers and resistant starch can be helpful for those with IBS, colitis, etc. Long story short: not all fiber is the same, so don't treat it as such.

75d65450b6ff0be7b969fb321f1200ac

(2506)

on February 12, 2013
at 07:46 PM

I believe "indigestable-to-humans" fibers are a leading cause of IBS and leaky gut, as explained in Elaine Gottschall's book 'Breaking The Vicious Cycle'.

1
4debe57f81d507bcb844f10b2ef38a83

(398)

on February 12, 2013
at 05:12 PM

In the case of something like fresh corn on cob, where the kernels might pass through more or less whole, then yes. Otherwise, no. The body is very efficient at extracting sugars from food.

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on February 13, 2013
at 01:03 AM

Corn, despite looking undigested, is digested.

Medium avatar

(10611)

on February 12, 2013
at 07:10 PM

The same thing applies to a lot of uncooked vegetables. Raw carrots have a much lower glycemic index than cooked carrots.

0
7d46edca72c2f8347f65d7b734d1f1eb

on February 12, 2013
at 09:55 PM

Part of the reason that I asked the question was reading another question on PH if weight lose doing paleo is from the food itself or calorie restriction it potentially causes. As an example there was a question relative to a doctor thinking that it is just calorie restriction and he suggested that if you did Paleo at X calories and SAD at the same X calories you'd loose the same weight. Clearly and over simplification there since you're not even considering the quality of food - but I am still pondering if there is a secondary question there of our bodies being able to digest the non-paleo foods and how many calories are getting into our system. Hope that makes sense since I don't think I'm being very clear. :-/

0
4b7e828232c7d6a5aab2265814647530

(10)

on February 12, 2013
at 07:25 PM

Another factor is phytic acid which is very high in grain germ. Phytic acid is an enzyme blocker so it can prevent efficient digestion and nutrient uptake.

-1
Medium avatar

(10611)

on February 12, 2013
at 03:48 PM

Are you kidding? Our ability to digest fat/carb laden junk foods EASILY is the underlying cause of the obesity epidemic. I had no trouble transforming frosted mini wheats into 50 lbs of flab.

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