He might be self brumating, many leos do this without the aid of lights they can just sence the seasons.
Dont be worried unless it starts to dramatically lose weight, it should still eat a little if it feels hungry, keep up your normal maintenance.
It's not unusual for them to eat less. I switched feeding from every other day to every third day about a month ago as breeding season ended. As of last week they aren't that hungry even with the every third day feeding. This has been pretty much how things have gone for the last several years.