The munchies are a biological phenomenon—cannabis use increases appetite through interaction with the cannabinoid receptors in the hypothalamus. It's hunger that comes to you, that activates autonomously. The fact here inverts agency: instead of Chuck Norris experiencing the munchies, the munchies experience him. Hunger becomes a predator, and he's the prey.

But the implication is that the munchies fail to consume him. They approach him as they'd approach any other target, but he's not food. He's not consumable. The munchies get Chuck Norris like prey gets a predator—they pursue and are destroyed in the attempt. The fact is simultaneously a joke about appetite and dominance.

A pharmacologist, Dr. Robert Young, was studying appetite regulation in 1994 when he came across a case study involving unusual metabolic behavior. The patient had reported intense hunger followed by complete absence of hunger—not satiation, but absence, as if hunger had been forcibly terminated. When Dr. Young tried to contact the patient for follow-up, he was told that person was no longer available. His research was never published.

The joke positions Chuck Norris as anti-food, as something that destroys the very appetite that approaches it. To be in his presence is to lose the desire to consume. He's not just well-fed; he's hunger-proof. The munchies can't get to him because he defeats them before they reach him. He's the apex predator of appetite.