Consistent exposure to cold might increase brown fat, while living in the tropics might lead to less brown fat.

“But how to activate brown fat if you are consistently exposed to cold? So if you live in the Arctic and you go out jogging in the winter, maybe that will increase the amount of brown fat you have. If you live in the tropics, maybe you have less brown fat. I don't know. I don't know of any studies which have looked into that.”