Macronutrient Metabolism

The documentary omits fat as a macronutrient, presenting a false binary between carbohydrates and protein. The body can synthesize glucose from protein via gluconeogenesis when dietary carbohydrate is absent. Even on an extremely low-fat diet, the human body still burns approximately 50% fat and 50% carbohydrate. The brain can derive up to 75% of its energy from ketones, making the claim that it runs exclusively on glucose physiologically false. On a fat-adapted or ketogenic diet, roughly 95% of energy comes from fat and only 5% from carbohydrate. Carbohydrates produce blood sugar spikes and crashes, and chronic consumption is the mechanism by which insulin resistance develops.