I'm happy to vary my diet according to what's available locally. Eating the local supermarket food is a major part of living in a place, and travelling for me is very much about living somewhere, not just going there. However, it can take a little while to find the local dietary equivalents for some things, but sometimes it's the variation in prices which can surprise. Consider cheese, and I'll convert all prices into GBP/Kg for a nominal basic cheddar:
UK: GBP 6 - 10 / kg
US: GBP 14 / kg
Canada: GBP 32 / kg (yes, it took me a few minutes to realise)
Israel: Hard cheese not available.
On the other hand, I'm flying back to Canada on Friday, and the price of fresh fish in Vancouver is far less than England, so perhaps I'll just live off that.
Edit: I never understood this pre-sliced cheese thing. Do pepole not own knives?