The key for someone to be identified as having a dadbod is that he has to show indications that he once took care of his physique and has simply neglected the gym of late.
The dadbod is the fruit of years of Judd Apatow and Seth Rogen comedies celebrating the bros: man-children who love spending time in their man-caves drinking beer, watching TV, and generally being the teenagers they will always be, while being, deep down, more sensitive and sincere than any well-chiselled pretty boy.