1.0 Mechanism & Biochemistry of Fructose Metabolism

Fructose metabolism is distinct from other fuels because it bypasses the body's normal regulatory checkpoints. When fructose enters the cell, it is rapidly phosphorylated by fructokinase (ketohexokinase, KHK), consuming ATP in a single burst. This sudden drop in energy leads to the production of uric acid, increased oxidative stress, and reduced nitric oxide, which restricts blood flow and energy delivery. Mitochondria respond by "shifting down," slowing energy output while increasing fat storage.