In October of 2018, Eli Lilly was a mid-level pharmaceutical company, valued at not even half of Pfizer, but the company had a secret — a weight loss drug called Mounjaro.

There are a handful of these drugs: Ozempic, Wegovy, and Rybelsus. Mounjaro is the latest and most effective. It’s also expensive.

If your insurance doesn’t cover it, it costs between $10,000 to $18,000 a year. Not only would Mounjaro help make Eli Lilly the most valuable pharmaceutical company in the world, but it could break America’s health care system.

We dug into why.