Re: How do you get a 2 year old to eat?
I've heard that if they haven't been introduced to it before they are 2, then they are unlikely to try it once they're 2 - sounds like what you're experiencing!
I agree that smoothies are a great way to pack in nutrition (strawberries, bananas, yogurt, milk, ground flax seed, other berries, juice, even some veggies can be slipped in unnoticed).
I've also heard of mamas simply making meal time more fun. Some fill a muffin tin with various "dips" and "dippables" - ranch dressing, peanut butter, honey, carrot sticks, celery, broccoli, apple pieces, cheerios, crackers, etc.
My daughter just turned 1, and I'm trying to offer her a wide variety of foods just so that we don't have to deal with introducing many new foods when she's older and likely to reject them. Not sure if it's going to work, but we'll see...
Good luck with your DS - I'm sure he's getting enough nutrition, even if it seems like he's not. You could always give him a multivitamin each day to help out.