We never insist DS eat anything. Lately, since he was over 2.5 years we have been asking him to try (because he started saying he didn't like stuff) and telling him that he doesn't know whether he likes it or not until he tries it. He is a really logic based thinker so because that makes sense, he will usually try something. I always serve him what we are having but we dont' insist he eats any of it and he rarely finishes his whole plate.

I was forced to eat revolting stuff as a kid and also to finish my plate every meal and I tend to overeat now and I think it's because I never trusted myself to know what I felt like and when I was actually full. My parents decided that for me I know that's a little off topic from your OP but to me it's all related. I make a conscious choice to let DS decide when he is hungry, how much he wants and what (within reason) he eats. We don't do rewards or punishment in other areas though so even if he doesn't eat much of the main meal, he can still have a small amount of dessert (DP and I don't really eat dessert). DS eats a wide variety of food voluntarily so when he doesn't want something I don't push it. I will often given him a very limited range of choice if he doesn't want any of what is on his plate for dinner - because I think a lot of the time at his age (2.5-3.5yrs) it's about having choices and having some control (not that he actually doesn't like the food).

HTH. I really think that how parents handle food issues is a direct reflection of how they parent generally and what their style is so just try a few different approaches until you find the one that suits you and your son.