Belly fat is the accumulation of abdominal fat that results in increased waist size. It is also known as central adiposity or abdominal obesity. Many people have concerns about too much belly fat, and a variety of factors can cause you to get a bigger midsection. People often put on more belly fat when they become middle-aged, after pregnancy, or when they eat or drink more calories than they burn. They don't call it a beer belly for nothing. But no matter what the cause, a bulging belly is something many people want to reduce.