Breasts and ass?
Those can't objectively be called "fat".
With breasts, there's obviously a million and 1 ways to measure them. Do you use height, width, areola size, or even buoyancy? It's hard to say.
With asses, many people would say that there's no such as a "fat" ass. The average person might agree to a blurry line on what is an optimal/acceptable amount of cellulite content or maybe at least on whether the ass must point up or down but I think I do well by those standards, woolly-nuts.