Determining hunger should be done using the calorific value of traditional stadium food. For football, that's a pie. We'll go with meat and potato as that's a classic.
A meat and potato pie contains approx 430kcal *. A ham sandwich contains 230kcal*, so each stadium goer would need a minimum of 1.8 sandwiches to sustain them.
* according to the first result on google for "calorific content in X"