GLP-1s and the ‘Wild West’ of Wellness

Julia Belluz, a New York Times opinion writer and co-author of Food Intelligence, joins Ezra Klein to unpack GLP-1 drugs like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). Originally approved for diabetes, these synthetic versions of a natural gut hormone have surged in use—one in eight Americans now takes them—driven by weight loss effects rivaling bariatric surgery, alongside unexpected benefits and risks in a culture primed for quick fixes.

Core Mechanisms of GLP-1 Drugs

GLP-1s mimic a hormone produced in the gut, brain, and pancreas that signals satiety after eating. For diabetes, they prompt insulin release only when blood sugar is high, avoiding hypoglycemia risks tied to standard insulin. Weight loss—typically 15-30% of body weight—stems not from boosting metabolism but from suppressing appetite via the brain's GLP-1 system. The drugs cross the gut-brain barrier, mimicking a toxin signal (like food poisoning) to dial down hunger and induce nausea, common side effects. This overrides the brain's predictions of reward from calorie-dense foods, which evolved for scarcity but now clash with industrialized hyper-palatable options. Hunger, speakers note, is less a stomach growl than a brain-led "symphony" of signals, influenced by over 1,000 genetic variants in common obesity, making willpower an unreliable lever amid poor environments.