Re-reading this thread, something caught my attention. Monty is 23" and 160 g.? My Olie is roughly the same length, and he's 255 g. But when I pulled him out of his cage at the vet, the first thing out of her mouth was that he was thin and underweight. He doesn't look underweight to me, and if yours is only 160 g. at the same length, I don't feel so bad...

I'm starting to think this vet was smoking a little bit of wacky tobacky before she saw me, even though she's part of ARAV (I forget what exactly that means, but I know it's the national reptile veterinarian association).

Yep, I double checked my weight and length measurements. Monty is 23" and 160 gr. (although he just ate two mice so he might be a bit more). I wish there was some sort of "snake Body Mass Index" that you could figure out ideal weight for size.
I've seen a lot of Ball Pythons that are MUCH MUCH thicker around the middle than Monty, but I'm pretty sure he's on a proper diet and at a good weight now. He had tapeworms when I got him and was only 114 grams, so he's really put on a lot since then, but it seems really evenly distributed.
I can't imagine yours being called thin/underweight... but my vet said that BPs should be kept at 80-90 % humidity.!!!!!!!!!!... so I wouldn't trust all veterinary recommendations.... maybe she's used to seeing a lot of power-fed, overweight snakes!!!

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Andrea