Slight Weight Loss

I have a question about weight loss...Paco has slowly been losing weight over the last week. Now this all started when I tried to figure out some way to keep him from going under his liner each night. (After his bout of mites and on paper towel for awhile, he has decided that he likes to be under the liner instead of on top of it) I have used double sided tape to keep the liner down and so far it has worked. But he has lost weight. He is still eating and drinking fine...still the same amount of stool as before. Everything else is the same except he cant go under the liner and the weight loss. Should I be concerned?? I also tried adding another food into the mix a couple weeks ago and he totally went against that...so maybe that had something to do with it as well?? I don't know, just want to ensure that I am doing the best I can for him.

Right now the only food he will eat is Solid Gold. I cant even find another food that he will eat. As for bugs and extra treats...its a no go as well...just the cat food...I know that everyone says a mix of 2-3 cat foods is best. But is there anyone else out there who is only feeding one food?

He has been on Solid Gold since just after we got him in Jan, the only other thing I thought it could be is the stale food as we were getting close to the bottom of the bag. So we opened a new bag. Still eating around the same amount, just not gaining weight.


Thanx Everyone.