Judes best guess.

It seems the human body does adapt to cold conditions given the right process. Once adapted, then, where as a person not adapted to the cold would normaly shiver the person who has adapted wouldnt.

Seems like the more brown cells the more heat is generated by the body when put in to a cold enviroment. There might be more to it than that.

In the experiment they say that the more than the usual amount of body heat generation is a by product of that form of meditation?
It would seem that extra body heat generation would happen anyway given the right conditions. How much heat generation is another question.

Jude .