I think trisharau is on to something. Your relatives are comparing you to the "previous you", and they are probably not used to the change yet. Once your new look becomes "normal" to them, they will probably stop the comments.
The other theory is that you played the role of "the fat one" in your family, and they don't like you changing the status quo. Now maybe they have to make you "the skinny one" to keep the family dynamic going. Not a pleasant thought, but if they are making you cry, it sounds like there is some sort of dysfunction going on.
I hope the first theory is the right one.