A loin cloth?
Sorry - I'll stop being flippant. When I have been for treatments, I have generally gone after work, and been in everyday clothes. The therapist (in this case a GP friend) just asked me to remove my shoes and socks for needles in my feet - Ialso had to loosen my blouse for the two points at the base of my neck (migraine treatment). When I went for a low back problem, I removed my trousers, and was draped in a sheet to keep me warm.