New studies seem to imply that food deserts are a myth. Healthy food is apparently plentiful even in inner cities where fast food outlets are in abundance. Also it's not just a question of are there full service restaurants and supermarkets but what are they serving/selling. A full service restaurant may serve up veggies but if they're smothered with cheese they're not exactly healthy.
As I've said many times on the show, you are what you eat so even if fresh produce is available you have to actually eat it and skip the fast food outlet.