Buns put on weight the same reason we do. Bad diet, lack of exercise, etc. I”m not aware of any special health issue that causes them to chunk up.
When her other bun went in for her spay, the doctor actually did a little bit of “Bunny Lipo” because one of the fat pads were surrounding the uterus and they showed it to me. Once I got over my bout of queeziness that I get whenever I see ANY internal organ type stuff, I was SHOCKED by the size of it. It was literally 4″x4″x1/2″ in size!
If my girlfriend doesn’t find a new place by the end of this week, she’ll be moving back east to continue her doctorate (don’t ask about this – it’s been insane even for ME to follow it) and she’ll need someone to babysit her bun for a month while she gets settled. During that time, I’m going to put Fitz through a bunny ‘fat camp’ and see if I can’t get him to shed a pound in a month, as well as get him accostumed to a new diet routine.