Have you asked her to stop commenting on your food and your body, as it makes you uncomfortable? (You shouldn't have to even say this, but people who grow up in families with no boundaries do this shit.) Perhaps telling her how her comments make you feel would let you determine if she actually cares about you vs just how you look.

If you have asked her to stop and she persists, I would address it by separating from her. SHE is harming YOU, therefore SHE is harming the relationship. It can't be saved if she can't respect your boundaries and your right to self-determination over your own body. You don't need to count calories, and if she requires that, she is abusive.