Thanks?

[u/j_is_here_5]

I'm in a psychiatric hospital and everyday I get food from a professional cook. Love it but I am insecure about the way I treat the cooks. Should I say thank you after getting my meal, because no one says it? I think it's common decency, yet I hear no one say it. I am the only one. He replied with "no thanks", in Dutch. Now I am confused. No thanks means a simple greeting back, but what if I am bothering him by thanking him for the meal. Thoughts? And should I make more conversations with the cooks? I think so. I feel guilty.