DD is a pretty picky eater... some days she'll eat ok and some days everything ends up on the floor. I try and give her 1 thing I know she'll eat (yogurt, turkey, oatmeal, bananas, cheese, bread, peaches, pasta) at each meal and add in new things or things she doesn't typically like. Sometimes she surprises us and eats a ton and sometimes everything ends up on the floor.
I have found that sometimes giving her smaller amounts at a time works (as in 2-3 pieces of food), sometimes giving her utensils help, sometimes a bowl to bang on, and sometimes feeding her ourselves works. But it just varies... sometimes she eats 2 bites and nothing gets her to eat. Our pedi isn't worried at all, and her weight seems to be ok so I'm not concerned yet.
I have heard that you shouldn't focus on what a toddler eats in a day but rather over a week, or even 2 weeks. And one of my friends pointed out that toddlers often eat what their body needs, and it could be that she's doing that (DD went through a huge carb phase when she was gaining more motor skills, so she may have just needed the extra energy)