DS1 is 4. Tea is an all-singing, all-dancing festival of whinging. "I don't like this", when he hasn't tried it, etc etc. He gets dessert (fruit or yogurt) but only if he's eaten well. If he really hates tea, he can have toast as a supplement.
Today we lost it with the whole whinging and shouting thing, and said "if you moan or shout again, you will be done with food, no more tea, no dessert." He had a small whinge, was warned again, and then a big shout about something, so he was taken away. (He tried to hit me, too, but not hard.)
He had no more tea, no dessert, no fruit. I think we're planning to stick with this and see if it makes mealtimes more pleasant. We're continuing to be ok with him not liking things, as long as he's not horrible about it.
What are your mealtime rules? How are they enforced? Do they work?