My BP has refused to eat for the past 3 week and she's lost 60g is that to much? My husbandry is fine so I'm not sure why she won't eat
Depends. Did she weigh 61g or 4000g before the weight loss? Did she deficate during that time? All things that are important to know before anyone gives you an answer worth listening to.
If there is no deficate and the scale has good repeatability... that is concerning in such a short time, although a large animal maybe less so. Generally I accept about 3% weight loss every few months of fasting. This would be adults. I personally have never had a sub adult fast, ever. I have no idea of what is acceptable there. I would be concerned to have a little snake fast at all, personally speaking.