It’s an old joke that men with expecting partners gain weight along with their female counterparts—and have to then participate in post-pregnancy weight loss efforts—but it turns out there may be a biological reason for this weight gain. It’s often called “sympathy” weight gain, but really, it’s most likely due to hormones. It’s not so much that men who are preparing to become fathers for the first time are just eating more, or eating less carefully than usual. Instead, they are most likely experiencing hormonal changes that make it harder for them to keep the weight off. Yep, men go through hormonal changes during pregnancy too, and testosterone levels may drop enough to interfere with metabolism and cause expectant fathers to gain a few pounds. This hormonal phenomenon has been highlighted in recent studies that indicate that hormonal shifts during pregnancy may affect men as well as women.