True but once in a while you dont get to choose. Once I was visiting my parents and they really wanted to go out to this restaurant that specializes in pot pies and was really close by. So I was dragged along
My suggestion for that situation is to say something like, if you really want to try one of those pot pies then I'll be happy to keep you company but I'll just get a drink. And I'll say that we need to organise it so I can eat either before or afterwards. I don't want to deny someone the opportunity to try something they couldn't usually have (if they lived close by to this place I'd be annoyed!) but I'm not going to risk my health.
For any advance planned eating out my friends and family always let me pick (or I give them a choice of places safe for me and they pick from them). Spur of the moment stuff I see if there's anything I can have and if not, I have a drink and grab something later. On a family trip recently I couldn't eat much at all at my step brother's place but my brother would stop by McDonalds on the way so I could get fries and a drink which felt like a treat (plus I had food in the fridge in the hotel) and so I could be all "oh, it looks delicious but I'm really full" with all the family members I didn't know well and didn't want to get into it with.
it helps you realize what you are *actually* doing - enjoying a social activity with people you care about. If that means, in order to eat, you have to stop by a grocery store and buy a couple apples and a fresh jar of peanut butter so you have some food, so be it.
I really agree with this. Rather than feeling like you have no choice to be somewhere, or that you'd be better off missing out at home, you meet your physical needs and social needs but in a different way to how you might be used to. Now I eat out with friends to enjoy their company, not to have a great meal. I can eat well at home another time.