Blisters - good point - the lifestyle we lead leaves traces on the skeleton. We can look at diseases in past populations by looking at the traces these diseases have left on the bones - some of the more gross changes I have seen during my work have included large pitting of the skull caused by severe late stage VD (this person was most likely insane by the time they died), and some of the more hideous effects of ancient diseases like leprosy.
A fit healthy person engaged in lots of physical activity will generally have larger more obvious insertion points were the muscle tendon connects to the bone surface. A heavier person can still have been engaged in physical work - think of all the lifting a farm labourer would have done for instance.
As for fat people in the past - we have plenty of pictures of Henry 8th
, but as far as I know no-one has ever gotten to analyse his bones!! But other things come out in the wealthy in the past - gout for instance is always assumed to be associated with rich-living, e.g. drinking out of wine goblets that have a high lead content during the Middle Ages.
But, just so we dont confuse the issue - this isnt Evolution at play
. This is lifestyle, disease, and what hardships (or not) people have experienced during that life.
If two morbidly obese adults get together and produce a morbidly obese child, is that a genetic trait, or is it because they live an unhealthly lifestyle that the child is exposed to from the moment of conception? Now, there in lies the question......I would suggest it is lifestyle.