An interesting article, but some of the ideas are rather outdated. We should never assume that people (not "tribes") who do not subsist on agriculture represent some sort of pristine indicator of past hunter-gatherers, or that hunter-gatherers around the world can be compared. Cross-cultural comparisons of this kind are a relic of the 1960s and 70s, especially when used to guess how past peoples may have lived. It's also incorrect to say that agriculture automatically leads to a food surplus, as until very recently agricultural societies often had (and still do have) very bad diets. Native peoples in the American northwest produced large food surpluses and diverse diets without agriculture. As for the statue itself, it very likely represents a pregnant woman, the utlimate symbol of fertility.

This.

Also, hunter gatherer groups today are restricted to highly marginalized lands, the best land having been seized by agricultural concerns. In the pre-agricultural era the game would have been much more plentiful having not been hunted near extinction, the wild food plants more plentiful and varied. It is quite possible that at certain times of the year people could have gotten quite fat indeed, and women biologically and socially would have the greatest opportunity to put on weight. Also, the hunter-gather tribes in the Pacific Northwest and all around the artic circle tend to the heavy side.