Hello Dave,
an accurate measurement of BP can only be achieved in the resting state when you are free from anxiety/stress, and probably best done first thing in the morning on arising.

BP will fluctuate quite a bit during the day in response to external stimuli, or even having a cup of coffee/tea, so not accurate at those times. Even Doctors will allow for a BP rise to some degree in its measurement when patients visit their surgeries, because of anxiety and so on.

A normal BP can be achieved via the Fuhrman diet or plant-based one, so as long as you follow that, but pity about the "garbage" that creeps in. However, fasting has a habit of being able to reset our taste-buds and create a desire for only natural foods (my own experience and that of many others) and where adulterated/processed foods just don't cut it any more, even to the point of repugnance.

Good luck with your fasting endeavours, including the spiritual side of it. Many find though that this spiritual side comes more to the fore after toxemia is eliminated and the bodily energies are used exclusively either in healing or heightening the mental powers. I suppose this is what Jesus of Nazareth described as: "the peace which passeth all understanding".

Chrisb1.