Eli Lilly's new weight-loss shot matches gastric bypass surgery results, great news for obese patients and for Lilly's stock, but risky for people buying it on the gray market years before it is legal.

• Retatrutide hits three hormone signals at once instead of one, cutting hunger, cleaning up how the body handles sugar, and telling fat cells to burn themselves.
• Late-stage trials showed 30% body weight loss over two years, with no plateau — roughly what bypass surgery delivers, from a weekly injection.
• The obesity drug market is heading past $100 billion, and weight-loss drugs just made Eli Lilly the first trillion-dollar pharma company, with Novo Nordisk, maker of Ozempic, now playing catch-up.
• The downsides are real: faster heart rates, irregular heartbeats, a third of the weight lost coming from muscle, and a new nerve-tingling side effect nobody understands yet.
• It is illegal to sell for human use, yet biohackers and gym crowds are already injecting vials from Chinese suppliers and sketchy websites while the FDA mails warning letters it cannot keep up with.

Outlook: Eli Lilly is expected to file for approval within months, putting a legal prescription around 2028 — and the gray market will keep growing until then.