there is never one cause for any stress hormone being high. you could waste years trying to figure out the exact mechanisms behind all these things, or you could focus on these five variables every day: eating enough through the day and per meal for your current state, eating frequently enough for your current state, eating the right balance of macronutrients per meal for your current state, avoiding foods which cause you inflammation in your current state, and getting a wide nutrient spectrum from easy enough to digest foods. Life circumstances are also *just as* impacting on your body as nutrition - so you have to weigh those variables in as well to assess the situation accurately.
If you are measuring temp. & pulse per Broda Barnes method, taking into account how you feel at these measurements then....congratulations, you are doing the only human thing you can do to follow what Peat describes as the only valid protocol: "to perceive, think, and act." If you haven't already, look into the Clara Davis study and consider what it may mean to re-learn intuitive eating.