I would literally just say “Do not comment on what I eat anymore please and thank you.” You don’t owe an explanation for anything.
You are growing another human inside you. Your eating habits aren’t just you, baby also has influence on what you eat. So when you’re able to find things baby allows, go for it. You shouldn’t have to worry about what others think when it comes to you feeding you and baby. So long as you are giving baby nutrition they need, just let your friend know “I am eating what my baby allows me to eat. I am sending food to the child I am growing”
@Laura I’d leave out the “while I’m pregnant”. It’s not her business what OP eats in general
I’ve also felt uncomfortable when people make comments about how MUCH food I’m eating. It’s best to be frank and say something like, “I prefer if you don’t make comments related to my eating while I’m pregnant.” It should be as simple as that, and hopefully they will respect your wishes.