As popular as the new class of weight loss drugs are, the reality is that not everyone will benefit from them equally. But determining who will lose more weight on the drugs and who is better off with older medications has mostly been a guessing game, obesity experts told me. They’re excited about a new gene-based test that they can prescribe, developed by researchers at Mayo Clinic, that categorizes people into four obesity groups, depending on what factors contribute most to their obesity. And that in turn can help doctors decide which obesity drugs to prescribe, since the medications work on different aspects of weight gain. The test, available through a company the Mayo researchers created called Phenomix, also comes with a diet and exercise plan.

Here are the four types of obesity the test can identify; the test currently provides results about the first two:

• Hungry Gut: People who eat until they are full but get hungry again shortly afterward. This group can benefit most from the newest drugs like Ozempic, Wegovy, Mounjaro, and Rybelsus.
• Hungry Brain: People who never feel full.
• Emotional Hungry: People who eat to reward themselves or cope with emotional issues rather than based on physiological hunger.
• Slow Burn: People whose metabolism makes it difficult for them to burn calories efficiently.