We went to DL in August and just last week and between the two times, food prices increased. (I think it was right around labor day). Five years ago, we could easily feed 4 people (2A, 2K) on $100 a day and include a trinket or two at the end of the week in that amount.
Last week, we spent portions of 6 days at the park and spent about $800 on food (including tips at table service). We did Big Thunder Ranch BBQ and the Surf's Up breakfast as well as Carnation Cafe and then did counter service for the rest of our meals. We also had the AP discount so 10% off of full price.
Can you do it cheaper? Of course! If I could just convince my DH and DS that they didn't need a soda at every meal, it would be a lot cheaper. I think I figured we spent about $70 on soda pop alone!
ETA: I went back and counted and we only ate a total of 8 meals over the six days actually at the resort (park or disney hotels). We also did a snack every day though and those add up quickly. That $800 only counted what I paid in Disney GCs so it didn't include a lunch at Earl of Sandwich ($25), dinner at Mi Casa ($30), and dinner at McD's ($20). We had free breakfast at the hotel the first two days too. So the real number is $875 or $145 a day.