Metabolic health coach Marc Bates has released a comprehensive YouTube video examining the biological limitations of protein consumption and its impact on human evolution. The presentation challenges conventional dietary wisdom surrounding lean meat consumption by introducing the concept of the "protein ceiling."

According to Bates' research, humans can only process 35-40% of daily calories from protein before experiencing metabolic toxicity. When this threshold is exceeded, the liver's urea cycle becomes overwhelmed, leading to dangerous ammonia buildup and hyperammonemia.

"The protein ceiling is not arbitrary. It's a hard biological limit defined by the maximal capacity of the liver's urea cycle to detoxify ammonia," Bates explains in the video.

The presentation details the phenomenon of "rabbit starvation," documented in early American explorers who consumed only lean rabbit meat. Despite adequate caloric intake, these individuals experienced progressive organ failure due to extreme macronutrient imbalance.

Archaeological evidence supports the theory that early humans prioritized fat-rich animals over lean meat sources. Sites like Gesher Benot Ya'aqov show systematic bone breakage patterns indicating deliberate marrow extraction, often occurring days after the initial kill.

The video demonstrates how human digestive systems evolved with smaller colons and larger livers, adaptations specifically designed for processing animal fats rather than plant matter. This evolutionary evidence contradicts modern dietary approaches that emphasize lean protein consumption.

Bates concludes that understanding these metabolic limitations is essential for developing sustainable nutritional strategies that align with human evolutionary biology.