Unkind and unprofessional regardless of the truth of it.
Yes, he should have said, “The excessive weight of your buttocks is dragging your lower spine out of its natural curvature. This is causing your back pain.”
(I’m series. Just speak English to people. If they don’t understand, they’ll say, “Whuh?”)
Thanks for being decent. Wasn’t sure if there was many left :) I don’t think I’d make a big fuss, but I’d certainly change my doctor if he thought he could talk to me in street language.