A story in Phys.Org covers a report that suggests that Neanderthal body shapes were caused by their high meat intake. The story is at Study reveals how diet shaped human evolution

The Neanderthals had a bell shaped rib cage and a wider pelvis than modern humans. The story says that the researchers found that the high meat diet cause enlarged bladder and kidneys, so the body evolved to make room for them. At first glance this seems possible, but I have my doubts. The thing about it is that all previous hominids also had a body shape similar to that of the Neanderthals. In one book I read there is a comment that the modern body style was a complete change from all previous forms. This of course casts doubt on the possibility of the Neanderthals having evolved that shape to make room for their bladder and kidneys.

Bill Gill

this mans skeletal system doesn't look as if it has
changed , adapted , or as you may prefer evolved
over the years due to his extreme body weight that his
diet has caused.

this skeleton could easily be placed inside a man who
is not considered to be overweight at all.

so why should anyone consider that their eating habits can affect the evoloution of mans skeletal system?

The suggestion that the Neanderthal body form evolved due to their diet was not based on their weight. The authors hypothesized that the large amounts of meat they ate led to oversized kidneys and bladders. So that evolution might have led to the bell shape of the rib cage and the width of the pelvis to make room for the oversized organs. This has nothing to do with whether they were fat. In fact the Neanderthals were probably pretty lean. They were hunter/gatherers and worked hard for their food. They didn't really have time to get fat.

Being fat generally occurs when there is an abundance of food available to be eaten. Until fairly recently there was generally not an abundance of food. The normal pattern would be periods of plenitude interspersed with periods of hunger. Frequently winter would count as a period of hunger. The Neanderthals apparently ate large amounts of meat, which would be more available in winter than plant food. The last estimate I saw for the Neanderthal diet was that they ate 80% meat and 20% plant food. This is the sort of thing the authors were looking at.

In fact of course, as I mentioned, I think they are wrong. That is based on the fact the the ancestors of the Neanderthals, and of us, had bell shaped rib cages and broad pelvises.

Bill Gill

http://phys.org/news/2016-03-reveals-diet-human-evolution.html

I have not read either article yet, so I don't know if this adds anything.