Hunting for Fat: The Ideal Human Macros and the Lost Era of Megafauna

When we examine the macronutrient composition that best supports human health, the evidence consistently points to a high-fat, moderate-protein diet. Our metabolism is uniquely adapted to prioritize fat as a primary fuel source, particularly without carbohydrates. 

Yet, when we look at modern big game, the natural food sources available to hunter-gatherers today, we find a striking problem—most wild animals are far too lean to meet this ideal macronutrient ratio. If our bodies require more fat than wild game can typically provide, it suggests that our ancestors were hunting animals with far richer fat stores than those available today.

The answer may lie in the distant past, in an age when massive, fat-laden creatures roamed the earth. Mammoths, woolly rhinos, and giant bison were the dominant herbivores during the Ice Age, providing abundant nutrient-dense meat and, more importantly, large amounts of fat. These megafauna, some reaching weights of 10,000 pounds or more, were covered in thick layers of subcutaneous fat and had significant intramuscular fat, offering the perfect macronutrient balance for human survival. Their extinction around 12,000 years ago marked a turning point in human history—coinciding with the emergence of agriculture. This shift suggests we turned to farming not as a first choice, but as a desperate adaptation to losing our most valuable food source.[1]

Big Game Today vs. Big Game Then: A Macros Mismatch

Modern big game animals like deer, elk, and moose are comparatively lean. Their fat content is typically 2–4% in the muscle, with some larger species like moose reaching up to 10%. This poses a significant challenge for hunter-gatherers relying exclusively on wild meat. Protein alone cannot sustain human life indefinitely—excess protein must be converted into glucose via gluconeogenesis, which is inefficient and, in extreme cases, leads to "rabbit starvation," a condition where consuming too much lean meat without sufficient fat leads to malnutrition and death.[2][3][4]

In contrast, Ice Age megafauna carried far more body fat. Studies on frozen mammoth carcasses show evidence of deep subcutaneous fat deposits, with some estimates suggesting fat made up 30–50% of their body weight in colder climates. The bone marrow of large megafauna was particularly rich in fat, a prized resource for early humans. The evidence of extensive butchering and selective extraction of fatty parts—like marrow, brain, and organ meats—suggests that our ancestors sought out these high-fat sources first, reinforcing the idea that fat was the primary driver of our evolutionary diet.[5][6][7][8]

This raises an important question: If human metabolism evolved around a diet based on the fat-rich meat of megafauna, how did we survive when those animals disappeared? The answer lies in domestication.

Did Megafauna Go Extinct Because of Humans—Or Did We Start Farming Because They Went Extinct?

For decades, scientists debated whether humans overhunted megafauna into extinction. While early human hunting certainly impacted large animal populations, recent climate studies suggest that the rapid warming at the end of the last Ice Age played a major role in their disappearance. As temperatures rose, vast grasslands that once supported massive herbivores turned into forests and wetlands, reducing the food supply for these giant creatures. Many species, unable to adapt to changing ecosystems, went extinct.[9][10]

This shift would have created an existential crisis for hunter-gatherers who relied on these animals for food. With megafauna disappearing, humans had two choices: continue hunting smaller, leaner game and risk starvation, or find a new way to produce fat-rich food. The emergence of agriculture and animal domestication at this moment in history suggests that early humans pivoted to farming as a survival strategy—not necessarily because grains were an ideal food source, but because they had no other option.[11][12]

The Survival of the Fattest: How Domesticated Animals Saved Us

Faced with the loss of megafauna, humans turned to domesticating animals that could provide a reliable source of fat year-round. Unlike wild game, domesticated animals could be selectively bred for traits beneficial to human nutrition, including higher fat stores. This shift allowed humans to maintain a high-fat diet even after the extinction of the large prey we had evolved to eat.

• Cattle: Unlike their wild ancestors, domesticated cattle have been selectively bred to store large amounts of fat in their muscle tissue (marbling) and as back fat. This makes them one of the most calorically dense food sources available today, offering a close approximation of the megafauna diet.

• Sheep (Mutton): While smaller than cattle, sheep are another fatty animal that provided an essential food source after the Ice Age. Mutton is naturally higher in fat than venison or elk, making it a preferable choice for early pastoral societies.

• Goats: Though leaner than cattle or sheep, certain breeds of goats were selected for their higher fat content, both in their meat and milk. Goat fat, particularly from milk, became an essential part of pastoral diets in some regions.

The domestication of ruminants not only provided a steady food supply but also allowed humans to maintain a macronutrient ratio similar to what they had thrived on for millennia. This ability to produce fat-rich food may have been a key factor in human survival when megafauna disappeared.[13][14]

Did We Domesticate Cattle Because We Needed More Fat?

While mainstream anthropology often explains domestication regarding food security and convenience, there may have been a deeper driving force: the need for dietary fat. Without adequate fat, humans cannot efficiently absorb fat-soluble vitamins like A, D, E, and K, nor can they produce ketones, a crucial fuel source for the brain and body. Our brains, which are 60% fat, require a consistent supply of high-quality animal fats for optimal function.

We see this pattern reflected in traditional diets around the world. The Maasai of Africa rely heavily on fatty milk and beef from their cattle. The Inuit, who have limited access to land animals, consume high-fat marine mammals like seals and whales. Even in agrarian societies, animal fats remained a dietary cornerstone—whether from lard, tallow, butter, or fermented dairy.

If humans had evolved to thrive on lean meat, we would expect traditional cultures to prioritize it over fat. Instead, fat is always the most prized nutrient across every hunting and pastoral society. This suggests that the loss of fatty megafauna pushed humans to seek out new sources of fat rather than shifting to a diet primarily based on lean meat or plant foods.[15][16]

Modern Implications: Are We Still Chasing the Lost Megafauna Diet?

The modern dietary landscape is a far cry from our ancestors' high-fat, nutrient-dense diets. Many people today struggle with metabolic disorders, insulin resistance, and neurological diseases—all of which may be linked to the loss of the high-fat, animal-based diet that shaped human evolution. The anti-fat movement of the last century only worsened this disconnect, driving people away from the very foods that sustained humanity for hundreds of thousands of years.[17]

For those following a carnivore diet, the preference for fatty cuts of beef, lamb, and other ruminants isn’t just about taste but biological necessity. By seeking out the most nutrient-dense, fat-rich animal foods available, modern carnivores are recreating the macronutrient profile that our ancestors relied on for survival. A diet of ribeyes, brisket, suet, and marrow may be closest to the lost megafauna diet that nourished early humans.[18]

Conclusion: The Carnivore Diet as a Return to Human Optimal

The extinction of megafauna forced a dramatic shift in human dietary strategies, but our biology has remained the same. We are still optimized for a diet rich in animal fat, and the closest modern equivalent is found in domesticated ruminants. Whether it's fatty beef, lamb, or carefully formulated products like the Carnivore Bar, prioritizing fat ensures that we are eating aligned with our evolutionary blueprint.

Though mammoth steak may be off the menu, the quest for optimal nutrition is far from over. By returning to the fatty, animal-based diet that sustained our ancestors, we may not only rediscover peak health but also reconnect with the dietary principles that allowed humanity to thrive in the first place.

Citations

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2. ​Reed, Danielle, et al. "Product Yield and Fatty Acid Content of North Dakota Mule Deer, Elk, and Moose." Meat and Muscle Biology, vol. 3, no. 1, 2019, doi:10.22175/mmb2019.04.0013.​

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6. Nieman, Alan M., et al. "The Fat from Frozen Mammals Reveals Sources of Essential Fatty Acids Suitable for Palaeolithic and Neolithic Humans." PLOS ONE, vol. 9, no. 1, 2014, p. e84480.​researchgate.net+1pmc.ncbi.nlm.nih.gov+1

7. Prates, Luciano, et al. "A Matter of Fat: Hunting Preferences Affected Pleistocene Megafaunal Extinctions and Human Evolution." Quaternary Science Reviews, vol. 312, 2023, p. 108150.​en.wikipedia.org+2researchgate.net+2en.wikipedia.org+2

8. Smith, Felisa A., et al. "Megafauna and Ecosystem Function from the Pleistocene to the Anthropocene." Proceedings of the National Academy of Sciences, vol. 113, no. 4, 2016, pp. 838–846.​pnas.org

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10. Sandom, Christopher J., et al. "Global Late Quaternary Megafauna Extinctions Linked to Humans, Not Climate Change." Proceedings of the Royal Society B: Biological Sciences, vol. 281, no. 1787, 2014, p. 20133254.

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13. Zeder, Melinda A. "The Domestication of Animals." Journal of Anthropological Research, vol. 68, no. 2, 2012, pp. 161–190.​

14. Evershed, Richard P., et al. "Earliest Date for Milk Use in the Near East and Southeastern Europe Linked to Cattle Herding." Nature, vol. 455, no. 7212, 2008, pp. 528–531.

15. Mann, George V., et al. "Atherosclerosis in the Masai." The American Journal of Epidemiology, vol. 95, no. 1, 1972, pp. 26–37.​en.wikipedia.org

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17. Brand-Miller, J.C., and S. Colagiuri. "The Carnivore Connection: Dietary Carbohydrate in the Evolution of NIDDM." Diabetologia, vol. 37, 1994, pp. 1280–1286.​pmc.ncbi.nlm.nih.gov

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