I have a 2 year old hermans tortoise that I am hibernating for the first time. When I weighed him before the wind down period he was 134g and 9cm in length. According to the J ratio he was on the heavy side. After 3 weeks wind down he now weighs 117g and the j ratio says he is too light so now I'm not sure what to do. I have cut down his light but he is inside so the temp is about 21 during the day and 16 at night. He is still active and seems eager to eat!

Your advice would be much appreciated.

The JR is unsuitable for that age. 

Do you have a room in which you can turn the heating off ? If so put it in there for a few days & you can then give it a short hibe..

It has lost quite a bit of weight, so I suggest you limit the hibe period to about 8 weeks. Your tort will benefit from hibernating & you will gain in confidence having tried it. 

Regards,

Tom