Something to consider would be local adaptations the emerged over very long periods of time. Most US residents come from a lineage that is (relatively) very rec

Something to consider would be local adaptations the emerged over very long periods of time. Most US residents come from a lineage that is (relatively) very recent to those lands. Also important to note that the US climate is significantly less homogenous, meaning that a somewhat universally high obesity rate is not going to be explained to a large degree by local climate. IIRC, relative obesity rates drop by roughly 40% for individuals with a college degree and in general correlates highly with socioeconomic factors in the US.