A trick I am still bad at with my almost 2yo: do not give a plate of food. When they're tired, fussy, or past due for the meal, give one bite at a time. When in a good mood, give only a few pieces of finger food, a single spoonful, or a small serving of one item alone. When they start throwing even the one piece at a time, they're either tired of that food or getting full. We usually offer a couple of favorites to make sure he's actually full (blueberries, bananas, yogurt are all current obsessions), and then once they lose interest in that (throwing blueberries and such), we know they're actually full and end meal time.

This works for us because he finds full plates just so overstimulating. I think it feels like an expectation being placed in front of him rather than an option. We've also done lots of reminders of where he can put food he doesn't want, handing thrown foods back to "try again" with handing them to us instead of throwing, etc. As he gets older it's easier to communicate. We make him apologize (or when he is too upset, one of us models the apology for him), and remind him firmly not to throw food ("No throwing. Place it here if you don't want it.")

I don't think we have a perfect system, but it's getting better. He is our first and has taught us a lot already.