To provide a single anecdote, I am able to get full on two dollar menu items. You don't have to stick to what they define as a "meal" (i.e. burger, fries, soda). If I'm short on time or cash, I can get two double cheeseburgers, or a chicken sandwich plus a salad, for less than $3, drink a glass and a half of water with it, and be full until the next meal. Whether just anyone can do that is another question.