I'll add that years back when I too kept BPs, mine did this fasting also...not when they were young, but as adults, & around the same # of years. I'm been much happier
keeping colubrids & such- I re-homed my BPs to fellow herp soc members who were into them. That was long before there was a forum like this to help me de-code them,
but it wouldn't have mattered, they just aren't my favorite snakes.