Ripplin said:

Yes, his head somehow became more squat as he aged. :p

Well spacing between bones condense over time (dunno about the head but skull formation also changes over time as well). Concerning nutrition on Dagobah isn't really calcium rich or anything it's explainable biologically. Also for all we know getting more squat is the process of their species evolution and perhaps they're were just as tall as us at one point (a mildly fightening thought actually... lol Like they look like Legolas and end up short and green! heh....).

Also consider that Dagobah may have heavier gravity than other planets... I know it's sounds like retconning but scientifically it's coincidentally explainable... (even though I doubt it's what GL was going for. ;) )