Why We Don’t Need Carbs: The Science Behind Gluconeogenesis
- Tammar
- Mar 29, 2025
- 4 min read
Updated: Jul 15, 2025
The below article is not medical advice, but it is based on facts, and links to studies are provided. By reading this article, you agree to the disclaimer (click here).
It’s a common belief that carbohydrates are essential for energy, but science tells a different story.
While glucose is indeed vital for certain bodily functions, the human body is fully equipped to produce all the glucose it needs — even on a zero-carb diet — thanks to a metabolic pathway called gluconeogenesis.
This article breaks it down in simple terms and includes a list of referenced studies and sources for further reading.
Glucose Needs in the Human Body
Certain cells and tissues — like red blood cells, the renal medulla, and parts of the brain — do rely on glucose for energy. But this doesn’t mean we must eat carbohydrates to meet that need.
The body can manufacture glucose from non-carbohydrate sources, specifically:
Amino acids (from protein)
Glycerol (from fat)
This internal glucose production process is called gluconeogenesis [1].
What Is Gluconeogenesis?
Gluconeogenesis is a natural, ongoing metabolic process. It primarily takes place in the liver and, to a lesser extent, the kidneys. It becomes especially important on low-carb, ketogenic, or carnivore diets.
Here’s what gluconeogenesis does:
Keeps blood glucose levels stable even without dietary carbs
Converts non-carb substrates (like amino acids and glycerol) into glucose
Fuels critical areas of the body that can’t run on fat or ketones, such as red blood cells and certain brain regions [2]
Adaptation on Low-Carb or Carnivore Diets
People following low-carb or carnivore diets don’t suffer from a lack of glucose. That’s because the body adapts beautifully:
This built-in metabolic flexibility is one of the human body’s evolutionary strengths.
Are Carbohydrates Essential Nutrients?
No, dietary carbohydrates are not classified as essential nutrients. Unlike certain fats and amino acids, which must come from food, carbs are fully optional.
The Institute of Medicine clearly states:
“The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed” [1]
Bottom Line
The human body does not require dietary carbohydrates to survive, or even thrive. Through gluconeogenesis, it generates the glucose it needs without carbs.
This isn’t a fringe idea or speculation — it’s a well-established, well-documented metabolic fact, backed by decades of research [1][2][3][4].
Food for Thought
Since we’ve established that carbs are not essential, the next logical conclusion is this:
There is absolutely no biological need for dietary fiber. (5)(6)(7)
Let that one sink in.
(scroll down for links to studies)
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Links to studies, articles, and videos:
1) Institute of Medicine (2005) – Dietary Reference Intakes:
“The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed.”
2) Cahill GF (2006) – Fuel Metabolism in Starvation:
“After a few days of fasting, ketone bodies provide the majority of the brain’s energy. Gluconeogenesis provides the remaining glucose required by the brain and red blood cells.”
3) Volek & Phinney (2011) – The Art and Science of Low Carbohydrate Living: Jeff Volek, PhD, RD and Stephen Phinney, MD, PhD, detail how gluconeogenesis supports glucose needs on carb-restricted diets.(Referenced metabolic science, not a clinical trial.)
4) Westman EC et al. (2007) – Clinical Experience with Low-Carbohydrate Diets:
“… humans evolved on a diet low in carbohydrate and have a robust system of gluconeogenesis.” https://doi.org/10.1093/ajcn/86.2.276
5) Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms: https://pmc.ncbi.nlm.nih.gov/articles/PMC3435786/
6) Deep dive on fiber by Dr. Kiltz: https://www.doctorkiltz.com/fiber-myth/
7) Also, individuals on carnivore or zero-carb diets often report improved bowel regularity, reduced bloating, and resolution of IBS-like symptoms — all in the absence of fiber. These anecdotal reports are increasingly being supported by clinical interest, although more studies are emerging.
8) Carbs & Sugars playlist: https://youtube.com/playlist?list=PLhDipacMMW7nle0hs2W3Qi1I8Kcy3jTKw&si=L9LF05cKTLY-6hBs
Disclaimer:
This article is not intended to provide medical, health, or dietary advice. I do not aim to convince you, but rather to empower you with facts.
Fact accuracy of this information: As always, I am committed to factual accuracy when presenting information. The insights and conclusions in this article have been thoroughly reviewed and checked for factual integrity. While AI tools like ChatGPT have been utilized as part of the fact-checking process, they complement a wider strategy that includes viewing current scientific research, expert analyses, and authoritative resources to ensure the reliability and relevance of the content presented. If there are any facts that I might have missed or that I have presented wrong, please contact me at tammars.com@gmail.com