A recent email ad from a telehealth company selling weight-loss medications features tennis-superstar Serena Williams.   “If you’re carrying 15-20 extra pounds,” it says, “medications like Wegovy can help jumpstart your progress.” For obesity doctors and researchers, this kind of messaging is problematic. The blockbuster drugs—known as GLP-1s—are increasingly marketed as lifestyle fixes to help take off some weight. But they are actually designed as lifelong treatments for chronic diseases, namely obesity and Type 2 diabetes.  That distinction matters. While nearly 18% of U.S. adults have taken a GLP-1 drug for weight loss or to treat a chronic condition, about half of people…