"I'm not fat, I'm just big-boned." I've never said that as an excuse for being fat, but I've had people say it to me, about me. Here is an article about bone size and relationship to obesity (there is none).
The fact is, although I am tall, my "frame" is on the small side. I took the wrist test in the article and the size of my wrist indicate small bones. My ring size is super small, and my feet are small as well.
So what does it mean when someone tells you, "Well you will never be thin, you are just big-boned."
It can translate several ways.
a) "I like being the thin one in our relationship, and I don't want to lose my identity."
b) "I'm afraid if you change you won't be my friend."
c) "I don't like seeing you achieve your goals, because it reminds me of how I am not achieving mine."
Another common comment, "Oh, you don't *look* --- pounds."
Does this sound like a compliment? I think it actually translates into a,b,c as well.
Yes, eating disorders are real, and people can be too thin, but that situation does not elicit comments about "big bones".
The fact is, whether positive or negative, what other people have to say about your weight is irrelevant. Obesity is so prevalent in our society that no one even knows what "normal" looks like anymore. A healthy weight is based on several factors, none of which are other people's eyeballs.