It’s best to weigh them “empty” after they poop if you want the most accurate information.
I weigh my snakes when I first get them and I stop weighing them once it gets too hard to stuff them into a container to be weighed.
I only keep a log of feedings and sheds.
Speaking of shed, how do I know? Her belly is not pink yet, but in the sun she is looking funny I took this picture cause of the different discoloration i see it looks bluish why? Is this a sign of shedding coming