Another thing you can try is activating the mitochondria in your brown fat by being a bit cold. The best way to do this might be the simplest—a brisk walk in a T-shirt on a winter day in a city such as Boston will do the trick. Exercising in the cold, in particular, appears to turbocharge the creation of brown adipose tissue.52 Leaving a window open overnight or not using a heavy blanket while you sleep could help, too.