It's really easy to see online too. Just browse online dating profiles for large cities versus suburbs (or walkable/transit cities versus car-only cities). People go from looking like actual people to looking like comical balloons.

Obesity is a national (global?) security crisis. It will cost trillions in preventable medical expenses, it causes excess fuel consumption, reduces productivity, and government+industry seems complicit in continuing the trend based on city planning and subsidy allocations. (Not to mention government policies/recommendations probably started the whole obesity crisis by promoting "low fat, high carb+sugar" eating practices ("food pyramid") for two dozen years across an increasingly sedentary population.)