Carol-Anne, a kit up up to about almost a year normally has a tummy.  With
whole animals it goes away with the first rut or estrus cycle.  Alters
usually don't keep it either.  If your ferret hits a year and keeps the
spare tire or love handles you got a fat ferret.  I ought to know since
I've had a few.
 
bill killian
zen and the art of ferrets
[Posted in FML issue 1375]