And actually, they do, in a sense! People who live in cold climates tend to generate higher levels of brown adipose tissue (contrast with white adipose tissue). BAT is more energy-dense than WAT and it is far easier to release the energy stored in BAT. Further, compression of adipose cells (as is seen in morbid obesity--the cells are pushing against each other) causes the release of hormones which cause hypertension, diabetes insipidus, and chronic inflammation--moreso from WAT than BAT. However, fatties, don't jump too quickly--if your body has more energy than it needs, it goes straight to WAT. BAT is created in response to cold climate and high energy need. WAT is created in response to energy excess. One great example of this: look at a bunch of pictures of active Navy SEALs. A lot of those guys aren't super-ripped musclemen. They've got a little bit of chub going on. Just a leeeeetle bit. No one in the world would say that they're fat or have any lack of fitness; in fact, they're among the fittest humans alive. The extra fat that they have is useful for protection against the cold water in which they work and protection against energy depletion for the incredible energy output they require from their body for long durations. If they didn't have the energy stores, they wouldn't last as long as they do. tl;dr: Eskimos are fatter than Mississippians, measured in brown fat. Mississippians are fatter than anything in total fat.