Interesting you ask... I had a kitty a few years back who started to siezure (it was a kitten in developement and his brother had the same problem). Belladonna 1M stopped the siezures however something was not right as the kitten literally bit 2mm off the end of his tail in the following weeks. One he had removed the offending part he stopped. Later that same cat was given Arnica as an adult which caused the same behavior, this behavior was stopped by giving Bell. Not sure if my story helps, but there it is. I would probably guess that "anxiety" would be a better description (might also explain why he is unadventurous) rather than depression in most cases, but the rest of his demeanor does not suggest this to be likely. Does he bite out the fur at the base or tip? At the base may indicate that he is itchy. Obese cats can not keep themselves as clean as others (they can't reach!) and many will scoot and be itchy and messy back there. We have had many obese cats, its amazing how active they become once some of the weight is off, what I am inferring is that his apparent "laziness" may be from the weight etc.