BAT or brown adipose tissue is one of the two types of fat found in humans. It is abundant in newborns and contains many smaller droplets of lipids with a lot of mitochondria with iron hence the brown color. As infants grow up, this tissue becomes similar in appearance to white fat but there have been many articles and research that relate BAT to skeletal muscle.
Functionally, BAT has a primary function – to generate body heat by burning fat. That explains why BAT is present in hibernating mammals and also animals that do not shiver. Based on reading research articles, BAT is a fat burning fat cell so it maybe good for us. BAT growth maybe stimulated by cold and therapies like hydrotherapy as well as books like the “The 4 hour body” by Tim Ferriss talk about the benefits of cold water and showers. Refer to article here.
Therefore, BAT maybe a good fat and stimulating its growth could be a valuable aid in burning fat. IMHO, cold showers in the morning, encouraged by yoga and other eastern philosophies did have BAT research behind it 
!
– Gary Saggu