I'm curious. Obviously they begin "cooking" for the flight long before boarding ever begins.

Usually, the meals are already onboard the aircraft when passengers start walking down the jetway. And usually during this same timeframe, the GAs are clearing upgrades.

Clearly it makes no financial sense to stock a 744 w/ 73-80 biz class meals if only 20 are expected. So I'd say board 23-25 meals. But what if, last minute, a family of 4 decides to upgrade and another uber-rich family of 4 comes along and drops $20k for biz tickets? Will UA deny the upgrades and/or CASH if they don't have sufficient food onboard?