Family says lose weight

I have grandmother and mother visiting I have a little bit of fat on me not to much I think I'm okay, lost ten pounds before they came and was feeling good. But my grandmother she's like 70 tells me you shouldn't eat, don't cook that! Glared at me when I do eat, I take walks and she said don't take walks run to lose weight.

She's always talking to my mom about women in the family who's the smartest in the family and the prettiest, it makes me feel bad overhearing everything, I literally cook quick and dash lock myself in my room, it's pretty depressing being in a room over eight hours a day I don't want to emotional eat, I'm a healthy weight but do have some areas but I am fine with it, I see people at stores who are like plus size models and I am okay with that and they are confident in themselves. I would also like to feel confident and have her accept me as I am what do I say to her?

Also I avoid her because she is the gossiper of all the family tells the family secrets talks bad about everyone I literally avoid her all day but I have to come out sometimes and it's stressful they took a one way flight here also I'm not to fond of her I remember as a kid she wanted us to call her by her name not grandma and that was off putting because as a kid I thought that meant she didn't want to be a grandmother

What can I say to my great grandmother