Is it my thoughts always ?

Hi Coaches
I have read in couple of books that the level of stress hormones in your body defines the level of anxiety you have. Many a times it makes me wonder am I feeling anxious because of my thought process or how am I handling my physical system. Say something makes me anxious I have thoughts like did I drink enough water, did I eat enough carbs? Is it always my thoughts which make me anxious (feeling) or it could be other factors too. Need some clarity here.