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Are people able to satisfy all the needs of a healthy diet without consuming carbohydrates?

My question includes the assumption that a person has no health condition that would prevent them from meeting their caloric needs with only fat and protein.

I'm also not asking about the practicality of eliminating all carbohydrates. If a person could consume no carbohydrates whatsoever, this other question would clearly matter a lot, but I'm not asking it.

If there are essential dietary components that happen to be carbohydrates, but are not converted into glucose, I'll say up front that it wouldn't satisfy what I"m asking. However, it would be interesting footnote on an otherwise correct answer.

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    $\begingroup$ While it's possible to live that way for some period of time, your body will be dying of stress. Your liver and kidneys will be first to fail. Your brain and muscles will struggle as well. Regarding your last paragraph, dietary fibers (comprised of different carbohydrates) are essential to maintain healthy digestive system and microflora, and the later has a tremendous impact on your immunity. $\endgroup$ – Eli Korvigo Dec 4 '15 at 19:31
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    $\begingroup$ @Christiaan it won't. Beta-exidation of fats produces acetyl-CoA that fuels the citric acid cycle when there are no sugar resources left. $\endgroup$ – Eli Korvigo Dec 4 '15 at 20:39
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    $\begingroup$ @Christiaan sorry for the typo, it was supposed to be "beta-oxidation". $\endgroup$ – Eli Korvigo Dec 4 '15 at 21:30
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    $\begingroup$ ajcn.nutrition.org/content/75/5/951.2.long Check this out. $\endgroup$ – 243 Dec 4 '15 at 21:55
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    $\begingroup$ @243 interesting article from Journal of Nutrition - I've never though of carbs as being essential - given that fatty acids can supply power via beta-oxidation and all the amino acids are either ketogenic, glucogenic, or both - and thus can supply the TCA cycle via anapleurotic reactions. Sounds like the Inuit populations with almost no carb intake do just fine - suggesting that dietary carbohydrates are not required for life - very interesting $\endgroup$ – Vance L Albaugh Dec 5 '15 at 16:34
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From a theoretical perspective this is a very interesting question, mostly because it is difficult to completely abstain from carbohydrate intake on a normal diet. Even the popular low carb diets of the late 1990s and early 2000s (e.g. Atkins Diet, South Beach Diet) were just that, they were Low Carb, Not No Carb.

We know there are essential dietary nutrients for humans, like essential fatty acids and essential amino acids. The reason that these must be obtained in the diet is because humans do not have the enzymes to synthesize these nutrients de novo (aka, "From Scratch").

From a biochemical perspective we know that fatty acids and acetyl-CoA cannot be converted back into glucose or other carbohydrate intermediates. This is because of the irreversible biochemical reaction catalyzed by pyruvate dehydrogenase, which converts pyruvate to acetyl-CoA. Thus, fatty acids (lipids) can be oxidized to acetyl-CoA (for the TCA/Krebs Cycle) but cannot be further converted to glucose within the body.

In terms of protein, however, amino acids are either glucogenic, ketogenic, or both. If amino acids are ketogenic, then this means they can be converted into acetyl-CoA for the Krebs Cycle. If amino acids are glucogenic, then it means that they can be broken down into glucose. The breakdown of amino acids can be used to synthesize glucose or for anapleurotic reactions of the Krebs Cycle.

As stated in the editorial noted in the comments of this question (From the American Journal of Clinical Nutrition), there are daily "requirements" for carbohydrates. However, it does not appear that any diseases are unmasked by very low to zero carbohydrate absorption (which is most closely occurs in the Inuit populations whose diet is entirely fat and protein).

So, if you ask the question "are carbohydrates essential components of a human diet?" the answer would be probably not. However, as mentioned above, carbohydrates are ubiquitous and it is impossible to abstain from all carbohydrate intake.


Below is a picture freely available online from this website (from Lehninger Principles of Biochemistry, 5th Edition) of the glucogenic and ketogenic amino acids and the metabolic intermediates to which they can be converted. This is how Krebs Cycle intermediates can be generated from amino acids and are not dependent on dietary carbohydrates.

Ketogenic and Glucogenic Amino Acid Pathways

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  • $\begingroup$ Wouldn't ketogenesis on such a scale (for all glucose needed) lead to severe ketoacidosis? $\endgroup$ – YviDe Dec 5 '15 at 18:39
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    $\begingroup$ @YviDe at first thought you might think so... but according to the article from American Journal of Nutrition it sounds like the Inuit populations live virtually as close to zero carbohydrates as you can get. It doesn't sound like they have any 'problems' like ketoacidosis. Prolonged starvation would also be a similar state - check out this great review from George Cahill...(med.upenn.edu/timm/documents/ReviewArticleTIMM2008-9Lazar-1.pdf) I would guess that the development of ketone bodies would be gradual enough in a conversion to fats and proteins that the body could buffer it $\endgroup$ – Vance L Albaugh Dec 5 '15 at 20:48
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    $\begingroup$ Interesting. Is there data on the actual carbohydrate content of the Inuit diet? Meat does contain some carbohydrates, e.g. muscle and liver tissue contains appreciable amounts of glycogen, and all animal cells are thought to have a few % carbohydrate content in the form of ribose, glycoproteins, etc. $\endgroup$ – Roland Feb 17 '16 at 19:37
  • $\begingroup$ @Roland I don't think there is specific data on Inuit... but that American Journal of Nutrition article referenced above in the comments to the question is kinda interesting - I agree with you, though, some carbohydrates are everywhere $\endgroup$ – Vance L Albaugh Feb 17 '16 at 20:51

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