I have several that 'fast' during winter months and others that eat all year round....

for the ones that don't eat, if they start to lose weight and show no interest...i raise their temp a couple of degrees and that usually takes care of the problem....i think it tricks them into thinking the weather is changing and prompts them to eat....return temps to normal after 2nd feeding

if they STILL don't eat, I return their temps to normal, and try offering each week....normally, they eventually eat

only once did I try a gerbil....and she ate it, but now she won't eat anything but gerbils or ASF rats...