My just-turned 3 year old eats pretty typically for his age, I think. All he wants is carbs, and he doesn't like anything to be mixed together. This is really throwing a wrench into my preferred one-pot meal style of cooking.
He's on the thinner end of the healthy weight range--about 45% weight for age, but because he's tall he's around 33% weight for height.
Note--my family eats omnivorously, and I've really started to notice how many meat & dairy products we eat. I wouldn't suggest modeling your nutrition on ours, and we're trying to change it. I think we eat healthier than a "typical" American family, but not as healthy as we should.
Also, my kid probably still has some reflux left over from infancy, so he still prefers to eat small amounts every couple of hours rather than bigger meals.
Breakfast: a small bowl of cereal and a cup of milk or 2-3 smallish pancakes with 1 slice of bacon and a cup of milk. In the winter it's oatmeal or polenta occasionally.
Snack: fruit and sometimes a stick of cheese
Lunch: Sometimes dinner leftovers, sometimes a turkey and cheese sandwich, sometimes just homemade sweet potato fries. Usually only about 1/3 c of food total (enough to fit into one of those small kid bowls). Another cup of milk.
Snack: his top preference here is always crackers. I suggest (and model) more fruit or veggies and it works about 1/2 the time.
Dinner: whatever we're eating. For the last few months he pretty much hasn't liked any dinner I've made. We have a "try one bite" rule that so far rarely works. When he does like dinner it's invariably when it's something starchy like homemade mac & cheese or other pasta. When he enjoys it he eats about 1/3 - 1/2 cup of food. Another cup of milk.
Bedtime snack: often yogurt with applesauce, blueberries, banana, or strawberries added. Sometimes just fruit. Sometimes dinner leftovers if he didn't dislike dinner.
He loves most grains, fruits, and beans. Sometimes he goes on a protein kick and asks for turkey for lunch and salmon for dinner, but that's rare. The only veggies he'll eat right now are corn, frozen peas (still frozen), potatoes and sweet potatoes, butternut squash, and artichoke ravioli.