It's more a matter of a average rates given circumstances.  For example, North American Amerinds have higher obesity rates than the Maasai.  Given the same circumstances, the pattern is unmistakable. Another factor is the massive change in obesity rates without change in population IQ.   This, and the resulting health consequences, pokes a hole in JayMan's theory that life expectancies are fixed and obesity is just a red herring for low-IQ people having a high mutation load.