I agree with the setting the timer (maybe set it for 25 minutes, then for five more minutes, so that he knows his time is almost up) and then getting him down from the table. If a child is not hungry, he won't eat, if he is, then he will. Now, if he doesn't get enough nutrition, have him drink pedialyte first (or in a popsicle) before he gets any food. Now, kids grow in stages. When they are learning physical things, they eat more for the energy they are expending. When they are learning mental things (words, relationships, new concepts), they eat less because they are sitting and pondering these new ideas. That is normal. And some kids just don't eat much. As long as the doctor says that they are thriving, don't force too much on them. That's my advice, anyway. Good luck!