What does "getting thick around the waist" mean? Is it a common phrase?

Rebecca

This is another way of saying that someone is getting "fat" or gaining weight. To get thick around the waist means that your waistline is increasing, due to added fat. People sometimes use the word "thick" to mean "chubby" or "fat. Ex: I saw myself getting thick around the waist during quarantine. Ex: He's getting kind of thick around the waist, maybe you should encourage him to exercise?