Take him to a doc to rule out any sickness you may not be seeing signs of. Then just sit back and try to relax. Your job is to prepare and offer food and it's the child's job to actually eat it. Toddlers undergo a facinating transformation and sometimes it's literally overnight. They simply do not need as much food/calories as they did just a few weeks earlier because they aren't growing as fast. The serving size for a 1 year old is tiny -- a couple teaspoons. He should still be getting/offered the adult version of the food pyramid, but the portion sizes are much smaller. Think about it.... 5-6 bites of a fruit and he's had the daily recomendation. They also tend to spread their meals out over a week instead of a day (no veggies for 4 days and then eat a bunch of them). Toddlers are also infamous for 'food jags' -- like only red food for 3 days then nothing but yellow for a week. This is one area kids have control over (and they know it!) so at all costs avoid a power struggle. Kids will eat when they need to, no healthy child will starve themselves to death. Just continue to put a healthy balanced meal in front of him and walk away -- your job is over. His job is to decide what and how much of that healthy meal to put in his mouth. Just make sure the between-meal snacks are healthy, too.
You also said 'every bite you give him'. Are you still feeding him? All my pediatricians have told me that a child should be 100% self-feeding by the first birthday (my kids hit it at 8 months). Just cut up the food for him and put it on his plate so he can feed himself. Pretty much anything is 'finger food' (although messy but kids are washable). He just might be sick of puree'd food.... all my kids (well, except my newborn, of course) refused to be spoon-fed by the time they were 7-8 months. It was them feeding themselves or nothing.
