Here's the bad news: You can't change what other people say.
Here's the good news: You know what other people are going to say, so you CAN change how you react to it.
I wish I had realized this a long time ago. I should never have let comments get into my head but they did and I can still remember them.
Try remembering that it has NOTHING to do with you. I know it seems like it does since you are the one they're commenting on but it's really ABOUT THEM. Hopefully, you've done it the right way and you should know that so don't let someone tell you you haven't. You don't know everything that other people do or eat anymore than they know everything you do so just remember that.
And eventually, you and everybody else will just get used to the "skinny" you and it won't be a thing anymore if you don't let it be by gaining it back
"Skinny" shouldn't be any more of a bad word than "fat" is. Maybe keep repeating it over and over to yourself till it sort of loses the meaning you're attaching to it so it's just a word? Just a thought.