The phrase "more belly fat" refers to an increase in the amount of fat that is stored around a person's abdomen. Belly fat, also known as visceral fat, can be dangerous for one's health and has been linked to various diseases such as heart disease, diabetes, and certain types of cancer. The phrase may be used in the context of discussing weight gain or obesity, where an individual is said to have "more belly fat" if they are carrying excess fat around their abdomen.