Bad eater???

My LO is 13 months and he was always really good at eating foods, puréed, table food, bite sized etc. he was never picky. Lately he started not eating as much? He'll eat and then start chewing his food and spitting it out.. He's been doing it with almost all his food lately.. he'll start off normal then a few bites later will start doing this.. or he'll grab the food and throw it down..

I want to make sure he's eating enough.. what can I do to stop this??? Or to help him get enough food in him?? TIA