How do you split food costs with a roommate?

So I've had roommates before but I've never had to split costs with them because we lived in a dorm. But now I'm moving into an apartment with a friend and we're working out how to split costs and such. We've got everything figured out except for food. (No offense to anyone or anything) but my friend is a little on the heavier side and she just eats a lot more than me in general, partially because I eat very little compared to most people. She wants to split each grocery bill in half, but I'm kinda weary of doing that because I would only be eating a small portion of that food. We will be sharing dinner each night, but for everything else we could just buy our own things. But that just seems a bit complicated. I was just wondering if anyone out there has a good solution to the roommate sharing food costs problem.