So I’m not sure if BMI had much to do with it vs. the rapid weight loss (but don’t quote me on that! Lol)
According to my weight loss records, at one week post op (when i got off the BP meds), my BMI was 39.7
And at my one months (when I got off cholesterol meds) my BMI was 37.0
...and both these numbers are way higher than yours.
Of course, there are other factors at play (age, pre-disposition, medical history, level of exercise, diet, etc), but this was my experience, in any case.
Edited to add: Today, my BMI is 21, so this likely has a circular effect on the lower BP these days?