I'm starting to realize that I'm... dense.
When I was done working in Alaska I was 190lbs. I have pictures from that time where my ribs are visible and I have exposed and very noticeable hip bones. 32" pants. The BMI chart says i should be 170. That ain't gonna happen. I'd be a walking skeleton at 170.
Have you ever been swimming in fresh water, like a pool? Do you float or sink? I sink. When I went through the safety crap on the ship I learned that there are different grades of life vests based on what floats you. I needed the second from the top to float me without treading water.