Did Humans Evolve to Eat Meat? Dr. Anthony Chaffee's Case for Carnivore
Dr. Anthony Chaffee makes his case that humans evolved as meat-eaters, explains two ways to start a carnivore diet, and weighs grass-fed vs. grain-fed beef.
By Harry Gray & Brett Ender · The Meat Mafia Podcast · Episode #76 · Aired July 19, 2022 · Updated October 27, 2026
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We first met Dr. Anthony Chaffee in person at KetoCon, then recorded this one over video. Before any of the science, we asked how a doctor ends up eating nothing but meat. It starts in a gym near Seattle.
Anthony grew up in America and played sports all his life. He got lucky, he says. One of the best MMA gyms in the world, AMC Kickboxing in Kirkland, was a few miles from his house. His coach there, Matt Hume, was strict about training and just as strict about food. He didn't drink and he ate clean, not out of misery but because he wanted to perform at his best. Anthony admired that.
He was waiting to turn 18 so he could actually fight, but rugby got him first. He made All-American in his second year and went on to play professionally in the US, Canada and England. Because he cared about both medicine and performance, he loaded up on biology, botany, cancer biology and nutrition classes. He wanted to feed his body exactly what it needed.
The turning point came in a cancer biology class at the University of Washington, about twenty-two years before we spoke. He remembers being taught that plants are living things that want to stay alive. Animals can run or fight back, but plants can't move, so many of them defend themselves chemically. He remembers thinking, "but vegetables are still good for you, though, right?" He says the professor told the class he didn't eat salad or vegetables and didn't let his kids eat them either.
"Screw plants. I just stopped eating them." (05:54)
He didn't set out to go carnivore. He just stopped eating plants, which left eggs and meat. He felt amazing. He'd also quit drinking during the rugby season, so at the time he gave the alcohol most of the credit.
Later he slid back. A little breaded chicken here, some plant foods there. Within a few months he noticed he didn't feel the way he used to. He was about 25 and honestly wondered if he was just over the hill. Years later, after seeing Dr. Shawn Baker's work, he looked back and decided the diet had been the difference.
Since then he's eaten strictly meat and water, with dairy only rarely and only as a condiment. He says the results came straight back, the same ones he remembers from his early twenties playing professional rugby:
"I felt like a superhero. I couldn't get tired." (07:29)
From there he started digging into the anthropology and the fossil record to see if the evidence backed up his experience. Today he brings that approach into his medical practice. Those are strong views, and many doctors and dietary guidelines disagree with them, especially on fiber.
That's the Anthony Chaffee we sat down with: an athlete who stumbled into a diet before he had the theory to explain it. Below is the rest of the conversation, from his case that humans evolved to eat meat to grass-fed vs. grain-fed beef and his two ways to start. We present his views as his, with timestamps. This is not medical advice, so talk to your clinician before you change your diet.
Listen to episode #76 · Watch on YouTube
TL;DR: Dr. Anthony Chaffee argues that humans evolved mainly as meat-eaters, pointing to the fossil record and stable-isotope studies. His two ways to start carnivore are going cold turkey or cutting sugar, carbs and alcohol first, then nightshades. His anti-fiber view goes against most dietary guidelines, so treat it as his opinion and talk to your clinician first.
Who is Dr. Anthony Chaffee? A medical doctor (MD) trained in neurosurgery and a former professional rugby player. He hosts The Plant Free MD podcast and is one of the best-known advocates of an all-meat diet.
Key takeaways
- He fell into carnivore by cutting out plants. "Screw plants. I just stopped eating them… And I felt amazing." (05:54 · Watch at 4:59)
- His evidence starts with the fossil record. He points to anthropology and stable-isotope studies of bones (11:18 · Watch at 10:23).
- He questions fiber. "If your body cannot break down fiber, you shouldn't be eating fiber." (17:32 · Watch at 16:37) Most guidelines disagree; see the caution below.
- He thinks grass-fed vs. grain-fed matters less than people think. "Silver lost to gold. Right? But silver still beat everyone else on earth." (59:46 · Watch at 58:51)
- How to start: clear the house, then step down. Cut sugar, carbs and alcohol first, then nightshades (1:00:55–1:02:52).
- For him, food is fuel. "food is nutrition… so that I can go out and do cool things." (1:04:45 · Watch at 1:03:50)
Timestamped highlights
Times are from the podcast audio. On YouTube the same moments come about 1 minute earlier (we checked against the YouTube captions); the YouTube links below already account for that.
| Time | Topic |
|---|---|
| 02:02 | Background: sports, rugby and medicine |
| 04:01 | Plant defense chemicals |
| 05:54 | "Screw plants": how he defaulted into carnivore |
| 11:18 | Fossil record and stable-isotope evidence |
| 13:06 | Traditional meat-eating populations |
| 17:11 | The case against fiber |
| 20:30 | Cholesterol, and how he reads the research |
| 24:15 | What he says he sees in patients |
| 27:03 | Forgotten history: Salisbury, Stefansson and all-meat experiments |
| 33:40 | Spreading the message, and the documentaries |
| 44:30 | His critique of The Game Changers |
| 54:43 | Bioavailable protein, fat and cholesterol |
| 57:48 | Grass-fed vs. grain-fed beef |
| 1:00:47 | How to start: cold turkey vs. a timeline |
| 1:04:45 | Food as nutrition vs. food as entertainment |
| 1:07:45 | The black-coffee experiment |
| 1:16:26 | Inflammation and pain |
| 1:21:51 | Cows, soil and the environment |
Did humans evolve to eat meat?
Dr. Chaffee's answer is yes, and he starts with the bones. "It's mostly, the anthropological data and the the fossil record… the stable isotope studies are, you know, very, very interesting" (11:18). From there he moves on to traditional meat-heavy populations (13:06) and to the early 20th-century all-meat experiments he thinks have been forgotten (27:03).
What are stable-isotope studies? Bones and teeth keep chemical traces (such as nitrogen isotope ratios) of what an animal ate. Researchers compare those ratios in ancient human remains with those of known plant-eaters and carnivores to estimate how much animal protein people ate.
Editor's note: the anthropology of the human diet is still debated. This section summarizes Dr. Chaffee's view and is not a settled consensus.
Plants, fiber and digestion
His own switch started with plants. After learning about plant defense chemicals (04:01), he cut them out entirely:
"Screw plants. I just stopped eating them… I was just started eating eggs and meat, and that was it… And I felt amazing." (05:54)
On fiber he goes further than most carnivore advocates:
"If your body cannot break down fiber, you shouldn't be eating fiber." (17:32)
A caution on fiber: this is Dr. Chaffee's personal view, not a consensus. Most dietary guidelines recommend fiber, and fiber has well-studied benefits for many people. Don't cut fiber abruptly, and talk to your clinician first, especially if you have a digestive condition.
Grass-fed vs. grain-fed: does it matter?
This is a surprisingly moderate moment. Dr. Chaffee says "the data certainly doesn't doesn't really show a big difference in in grain, finished versus, like, grass fed" (57:48). His verdict:
"Silver lost to gold. Right? But silver still beat everyone else on earth." (59:46)
That fits our own take: buy the best beef you can afford, and don't let perfect be the enemy of good.
How to start a carnivore diet (his way)
He offers two routes. The first is cold turkey: "throw all the crap out of your out of your house… out of sight, out of mind" (1:00:55). The second, for people who can't do that, is a timeline (1:01:07):
"Get rid of sugar, get rid of carbohydrates and alcohol… After that would be things like nightshades, potatoes, tomatoes, eggplants, peppers" (1:02:05)
"Dropping carbs day one and eating a lot more meat. Great. Doing that for, like, a couple weeks, then I'm, you know, I'm gonna drop, you know, nightshades." (1:02:52)
Food as fuel, not entertainment
The most quotable part of the episode is about mindset rather than biochemistry:
"I like ice cream. I like feeling like a superhero way more." (1:04:14)
"I eat once a day. I feel amazing." (1:06:05)
He also tells a story about a single cup of black coffee: "I was sore for the next two days after that from one cup of black coffee" (1:15:17). It's one person's experience, but it's a good illustration of how he runs experiments on himself.
Resources & brands from this episode
- Dr. Anthony Chaffee: YouTube · X @anthony_chaffee
- Brands read on this episode (sponsor/affiliate reads):
- LMNT electrolytes: drinklmnt.com/MEATMAFIA · paid link
- Kettle & Fire bone broth: kettleandfire.com/MeatMafia, code MEATMAFIA (15%) · paid link
- Carnivore Bar: code MEATMAFIA (10%) · paid link
FAQ
Does Dr. Anthony Chaffee think humans evolved to eat meat? Yes. He cites the fossil record, stable-isotope studies of human bones and traditional meat-eating populations (11:18–17:11). It's his view; the topic is still debated.
What does he say about fiber? He argues that because humans can't break down fiber, we shouldn't eat it (17:32). Most guidelines disagree, so talk to a clinician before you cut fiber, especially if you have a gut condition.
Is grass-fed beef necessary on a carnivore diet? He says the data doesn't show a big difference and that grain-finished beef is still a good choice: "silver still beat everyone else on earth" (57:48–59:46).
How does he recommend starting? Either clear the house and start cold turkey, or cut sugar, carbs and alcohol first and drop nightshades a couple of weeks later (1:00:55–1:02:52).
Related episodes
- #22 Dr. Ken Berry: 3 Things to Cut and How to Start
- #266 Dr. Anthony Chaffee returns: Reversing Chronic Disease Through Carnivore
- Pillar hub: Carnivore & animal-based nutrition → /health/carnivore/
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Disclosure: Meat Mafia hosts Harry Gray and Brett Ender co-own Noble Origins, a grass-fed beef protein with organs. We mention it where it is relevant, so weigh our take with that in mind.
Not medical advice. This post summarizes a podcast conversation for education. The views are the guest's own. Talk to a qualified clinician before you change your diet, supplements or any medication.
