I am no expert but he certainly didn't seem thin at all not did he display any odd behavior during the 5 or so weeks he didn't eat. My concern was just based on the elapsed time as a new owner not because I noticed him looking thin or behaving strangely. He is definitely thick and healthy looking at this time.

I am am looking into another heat source I have a red bulb heat lamp above his cage keeping the temp around 82 or so degrees. He is in a room alone where the door stays closed with no real traffic. I keep it that way to trap the eat in because it will drop to 79 or so if the door is open too much.

Humidity is not perfectly known but I have a large water bowl I keep diligently clean and full.