Supplies - Sending an army that will not starve ?

[Sombre]

No, there isn't a quick and easy way to do it.

You just have to work out how much each army needs before you move 'em. Or you could build lots of supply producing items and then you'll never have to worry.

If you're playing SP, I advise putting supplies on the highest possible setting, since the AI never even attempts to avoid starving its own troops and it removes a bit of micro from your game.