Absolutely not, it's complete bullshit. A "food desert" is a place where it's hard/impossible to find affordable or healthy food.  Therefore the statement is absolute bullshit without going any further at all.  I've lived in a place like that before where I had to drive over an hour to get to the nearest grocery store.  Did I turn into a fucking blimp.  Hell no.  I bought in bulk, repackaged my food so it could be frozen without getting freezer burn, and continued to eat perfectly healthy. It's just another bullshit excuse for laziness and deliberately eating like shit.