I don't like it when family members and relatives use me as an example to body shame to others.
How does it feel to have your body being compared to others?
Not good, even though I know that I'm not the only one with the problem.
Your resentment about your family is totally valid and understandable. They should not body shame others by using you as an example. It's wrong.
How can I deal with them? I don't know how but I feel the need to enlighten them about how their remarks make me feel.
I think you answered your own question. You need "to enlighten them" about how their remarks make you feel.