It's one thing to need to cut corners. It's another thing for passengers to UPGRADE and expect a meal only to find themselves 5 hours in the air without any reasonable amount of nourishment.

UA really needs to communicate to passengers BEFORE they get on the plane and say, "yes, we're charging you a premium fare/taking your upgrade instrument, but we're not serving a substantial meal, so you might want to make sure your belly is full before you get on our aircraft. Love, United."