As effective as the new weight loss drugs like Wegovy and Zepbound are, they don’t work for everyone. Mayo Clinic obesity expert Dr. Andres Acosta and his team studied thousands of obesity patients to understand which factors contributed to weight gain, from genetics to microbiome, metabolic characteristics and behavioral habits, and created MyPhenome, a genetic test that, together with a detailed questionnaire, categorizes people into four weight-gain types. One, called HungryGut, is most likely to respond well to the new weight loss drugs. People with HungryGut lost twice as much weight while on the drugs than the average user who didn’t take the test. “For the first time, we can identify the best responders,” says Acosta. But he stresses that the test and the medications alone aren’t the answer to addressing obesity—a comprehensive weight loss program, which includes those interventions as well as education about diet and exercise, are the most effective way for people to lose weight and keep it off.