Evolutionary #SCIENCE explains why #HUMANS ARE NOT DESIGNED TO BE PURE CARNIVORES LONG TERM. IT IS ALL ABOUT #INSULIN AND #GLP-1. These #FACTS will clash with your BELIEFS and OPINIONS but there is only one set of facts. #CARNIVORES: WHY A PURE CARNIVORE DIET IS NOT A GOOD LONGTERM DIET FOR MOST PEOPLE. Dr Cywes discussed the #evolutionary biology used by obligate carnivores v omnicarnivores v sugar eaters. #insulinsuppression v #insulinresistance. This is true for #cancer and #Alzheimer’s disease. Know the truth for yourself. Know the pros and cons then make a personal decision – and it’s OK to change it up. Know the scientific truth about how your body works. #carnivore #keto #diabetes #addiction #fatadapted #ketosis
🧠 Key Differences from Humans: Species GLP-1 Stimulus Notes Humans Carbs, fats, some protein GLP-1 mostly studied for glycemic control Cats (carnivores) Protein, fat GLP-1 still functions, but different stimuli
Very low insulin + high glucagon Gluconeogenesis + hyperglycemia
Lack of GLP-1/GIP Less insulin control, inflammation
Literature reviewed: LMHR studies doi.org/10.1161/CIRCIMAGING.123.016481 Soto-Mota A, Norwitz NG, Manubolu VS, Kinninger A, Wood TR, Earls J, Feldman D, Budoff M. Plaque Begets Plaque, ApoB Does Not: Longitudinal Data From the KETO-CTA Trial. JACC Adv. 2025 Mar 18:101686. doi: 10.1016/j.jacadv.2025.101686. Epub ahead of print. PMID: 40192608. doi: 10.1016/j.jacadv.2024.101109. PMID: 39372369; PMCID: PMC11450898
summerizer
WHY HUMANS ARE NOT CARNIVORES 🥩🥩
Dr. Robert Cywes explores the reasons why humans cannot sustain a long-term pure carnivore diet. He discusses the physiological differences between obligate carnivores and humans, highlighting insulin mechanics, GLP-1 hormone dependence, and how these factors influence our diet and health. Through an evolutionary lens, he explains that while a carnivore diet may be beneficial for weight loss and managing diabetes in the short term, humans require a balance of nutrients, including carbohydrates, to maintain proper hormonal function and metabolic health.
Key Points
Carnivore Diet Benefits
A pure carnivore diet can rapidly correct insulin resistance, aid in weight loss, and be effective for managing diabetes. Dr. Cywes advises this approach for short-term health improvements.
Insulin Production Mechanisms
Both obligate carnivores and humans require insulin to use sugar. However, the mechanisms triggering insulin release differ; carnivores rely heavily on amino acids from protein, while humans depend more on carbohydrates to trigger insulin through the GLP-1 hormone.
Limitations of Pure Carnivore for Humans
Humans cannot thrive on a strict carnivore diet long-term without suffering from insulin suppression. Our physiology requires some carbohydrates to stimulate GLP-1 production for adequate insulin response.
Physiological Adaptations
Humans are facultative carnivores, meaning we can eat a carnivore-heavy diet but cannot fully rely on it. Long-term absence of carbohydrates leads to downregulation of insulin production and GLP-1 signaling, akin to complications from standard diets.
Comparison with Hummingbirds
Hummingbirds, which consume high carbohydrate diets, do not develop diabetes due to their evolutionary adaptations that allow them to rapidly clear glucose from their system, contrasting with the slower glucose metabolism of humans.
Conclusion on Diet Balance
Dr. Cywes emphasizes that while a carnivore diet can be beneficial, a balanced approach that includes some carbohydrates is essential for human health to prevent long-term metabolic issues.
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he’s opening up like he’s talking to Vegans or something.
The Carnivore community is far more tolerant of … well … facts.
Yeah… it would have been nice if this think piece had some facts attached to it.
This continues on the Cywes insulin stimulation theory he spoke about earlier. https://hackertalks.com/post/11333564
He is making lots of very confident mechanistic appeals, just like his previous theory about GLP-1 signaling strength.
The counter point is the GLP-1 signaling doesn’t need to as strong in a ABF diet.
Admittedly there isn’t much research on this metabolic state, so he might be right, but he is making wild assumptions stated very confidently.
He calls the long term carnivore state “insulin suppressed” but you could also call it “insulin sparing, and glucose sparing”. Most of the body runs off fat, and the few things that need glucose (red blood cells, some brain cells) can use the glucose produced by the liver without competition.
The very long term carnivores on Reddit are pretty strict and have been for decades. I don’t think they see problems from this except that they find the advice to bring in some carbs days before a glucose challenge test to avoid the very slow response you get after years on just meat. I guess that’s them being insulin suppressed (which they fix with a small dose of carbs when their insulin response is going to be measured)
I do get a little lactose from Greek yoghurt every couple of weeks, but doesn’t everyone get a little exercise for their insulin each morning when blood sugar increases with dawn?
Watching this now. And my first thought: “of course our insulin system isn’t like a lion’s as we evolved pretty recently from a herbivore”
Funny that he thinks our gluconeogenesis won’t work because our insulin is too suppressed, and yet if I get a blood test at 07:00 I get a pretty high (border normal/prediabetic) reading. Whence cometh that glucose? If my insulin is insufficient how does it stabilise that high blood sugar by 9am?
It seems like his belief is that without regular carbs our insulin spent be there when we decide a load of carbs would be a good idea. Those long term Reddit carnivores reckon it takes less than a week to bring your insulin response back to normal
I guess that’s them being insulin suppressed (which they fix with a small dose of carbs when their insulin response is going to be measured)
Insulin sparing, they prime the pancreas to prestore insulin so it can be released quickly, because now we are in a carbohydrate rich environment.
I think the term of art is physiological insulin resistance, which is a misnomer. The body is still exquisitely sensitive to insulin, it’s just that it’s not preloaded the insulin into the pancreas for quick release.
Whence cometh that glucose? If my insulin is insufficient how does it stabilise that high blood sugar by 9am?
I don’t get this either. He’s a smart guy. He’s seen continuous glucose monitors, he even has a couple videos talking about them. So he knows exactly what the glucose levels are on long-term carnivores. His explanation is a mechanistic one not an observed one. And to me that means he’s just looking for some excuse
Now that this video has simmered a bit, some of the youtube comments are great
@CoachStephen (health coach, 6 years carnivore) - He’s lost it. There are 14 glucose transporters. 13 do not require insulin. GLUT4 is the only one that is insulin dependent for the most part.
@juice525 -
❌ Where he’s oversimplifying / partially misleading:
1️⃣ The “danger” of pure carnivore long-term applies mainly to some, not all humans. • Many people have done long-term zero-carb (years) without developing metabolic dysfunction. • Genetic variability plays a huge role. Some people tolerate long-term zero-carb quite well.
2️⃣ GLP-1 dependence is real but not absolutely critical for everyone. • The loss of GLP-1 function is not as fast or absolute as he makes it sound. The body has compensatory systems. • Many zero-carbers maintain good insulin sensitivity simply via very low glucose production and low insulin needs.
3️⃣ The claim that long-term zero-carb “becomes identical to the damage of a standard American diet” is exaggerated. • Even if mild glucose rises occur, they are not remotely the same as hyperinsulinemic, high-triglyceride, inflamed states seen on SAD.
4️⃣ Insufficient nuance about metabolic flexibility: • The reality is: some humans do maintain high metabolic flexibility on long-term carnivore. • Cywes sometimes paints the physiology too rigidly, when in fact, the range is wide.
Plus Cywes doesn’t account for inuit populations.
