[lamp_book]

Not advocating it, but you could look into Wim Hof's method: https://en.wikipedia.org/wiki/Wim_Hof. Critics do wonder if it has to do with his brown fat composition.

[ptah]

he has undergone clinical studies and his methods have been shown in a lab to activate brown fat

https://www.wimhofmethod.com/brown-fat

https://www.wimhofmethod.com/science