My son is two years old and has never been a good eater. He just refuses to eat anything. He'll usually have one bite of whatever we eat, but that's about as far as his interest goes. How can we get him to actually eat food?
You may just have a child that is a "grazer".
Our pediatrician asked us how our daughter was eating a while back and I said she just grazes and doesn't really eat a full meal at one time. It concerned me but the doctor told us as long as she was eating and didn't lose weight and wasn't weak or sick that she was fine. Your best bet is to take this issue up with your pediatrician since they know your child and can track trends in weight and health and give you ideas for how to make improvements since I am sure your child is not the first to have those kind of eating habits.
Infants are much more instinctive than us adults. They eat when their body needs food (although it takes time for them to learn to consciously interpret their body's signals). As opposed to us who mostly eat when it is time to eat. And, as others noted, they differ wildly in their eating habits. Some are just not into eating that much.
If your son is otherwise healthy and has more or less normal weight, I would say it is OK. As a wise Hungarian expert wrote: no child is ever going to starve if there is food available. Just make sure that the little he eats is mostly healthy, diverse food, not sweets or junk food snacked in between regular meals.
Also it is important to note that the growth of children is not smooth and continuous: they grow in spurts. During such a growth spurt they may eat 2-3 times more than average for a few weeks or months. However, between spurts, they may eat much less.
He will not starve and fighting with him will only give him attention, possible perpetuating the problem. Unless there is a weight issue of some kind, in which case speak to a pediatrician, just let it be. Don't give him snacks until snack time (2-3 hours after a meal) and don't let him fill up on liquids, especially before a meal. I found that when a child is about to make an academic leap they often don't eat well, as their mind is consumed with other things. Don't sweat it, he will be fine in the long run.