After years of diets, exercise routines, failed obesity treatments and shame for being overweight, the 49-year-old teacher from Missouri found a medication that helped her lose 25 pounds in three months. “It was life-changing,” she says.

In addition to shedding weight, Kay experienced other changes that seemed almost miraculous. She quickly noticed the painful cramping from her fibroids disappear and the swelling in her legs vanish. “I could go for walks again,” Kay told me. She even stopped taking Wellbutrin. “It became about far more than just weight loss.”

Then it was all taken away. The new diabetes drug Mounjaro was behind Kay’s weight loss, but when the manufacturer, Eli Lilly, changed its coupon terms her transformation became unaffordable — and unsustainable. If Kay wanted to continue to lose weight, live pain-free, and stave off a dreaded diabetes diagnosis, she’d have to shell out $1,000 every month – more than the mortgage on her house, and far more than the $25 per month she had been paying with Eli Lilly’s original savings program. Mounjaro, the name brand for tirzepatide, is one of a new class of nutrient-stimulated hormone-based therapies that’s changed the way type 2 diabetes (T2D) is treated. While similar therapies target a hormone called GLP-1, Lilly’s Mounjaro is the first to target a second hormone, GIP. Together, these hormones decrease appetite and delay gastric emptying, making a person feel full for longer. In a 2022 study on tirzepatide, participants saw an average weight reduction of 22.5 percent. In a separate study, Novo-Nordisk’s celebrity-endorsed Ozempic, which targets only GLP-1, showed an average weight reduction of 16.9 percent.

This critical side effect of Mounjaro — swift weight loss that rivals bariatric surgery — has made the drug a heated flashpoint between patients with diabetes, patients with obesity desperate to avoid a T2D diagnosis, people looking to improve their physical and mental health through weight loss, insurance companies, and Eli Lilly.

The conflict, which has been exacerbated by shortages of Mounjaro and two of its GLP-1 predecessors, Ozempic and Trulicity, has been intensified on social media. Diabetes patients think people with obesity are stealing their drug, as it’s currently only approved for the treatment of T2D (though FDA approval for the treatment of obesity may come as soon as this summer.) People with obesity are angry that obesity isn’t recognized as a disease. And users who can’t afford it say they’ve been abandoned by Big Pharma.

“I felt like a normal person for the first time in a really long time,” says Jordan Goodwin, a 30-year-old from Dallas who has polycystic ovarian syndrome, or PCOS. Goodwin lost 30 pounds with Mounjaro in three months before her coupon unexpectedly stopped working and the drug became unaffordable. “Now it’s all back — I’m insatiable. Should I let myself get diabetes so that I can get the medication that works?”

This is why Lilly’s decision to change its coupon terms hit patients so hard. “Not only were patients probably not aware that there was a time limit in the first place, but they moved the ball, so to speak,” Michelle Mello, a professor of Law and of Health policy at Stanford University, said. “They moved a goal-post up to create the dependence and then pulled the rug out even more quickly.”