I have seen a lot of people with Barb's age looking at least 10 years younger (if not more), its all about how you take care of yourself (diet, exercise, stress, etc). Barb was a sloth her entire life (I never ever seen her out of the house for too long, outside to just get some supplies when her orc slave cant do it for some reason). One of my doctor friends at college (a fellow Christorian, tho he does think its "too sad" now) said that Barb's "survival" at her conditions is nothing short of a genetical/medical miracle (but the former can only keep you going for so long until your life style catches up). He predicted (tho its just a prediction given he has not enough info outside of whats online) that Barb has around 1-3 years tops.