I'm like Manta Ray. I used to give in and give DS1 some fruit or something else healthy if he didn't eat dinner. But gave that up because he would hear me say 'dinner' and he would say no I want.... and not even try to eat any of his dinner. It is still a huge effort to get him to even try alot of dinner things, but I always make sure there is something in the meal he will eat. So if it's chicken for dinner, I make sure we have a cob of corn, or some oven chips or something I know he likes and will eat if he really is hungry. Often he will not eat anything, and will go to bed without having eaten since about 3.30pm. But I figure if he really was hungry he would have eaten something off his dinner plate. It's not like I'm not feedinghim and starving him. He eats well thgouh the day. A paed once said to me that you should look at a child's diet over a whole day, and a whole week even. If they ate copious amounts yesterday, it's possible today they will only peck at their food, and vice versa.
I know it's hard (beacause I still do it too!) but try not to worry. Your kids won't starve themselves. And they actually need alot less food than we think they really do.