The ephedrine/caffeine stack was a staple for many bodybuilders before the ban in the U.S., but for those countries where ephedrine is still legal, here is some good news. A recent study in the journal Diabetologia examined how 
it would impact brown adipose tissue (BAT). In rodents, BAT activation and increased energy expenditure in response to cold and sympathomimetic drugs is of considerably greater magnitude than in humans. In a randomized, double-blinded, crossover trial, they administered 2.5mg/kg of oral ephedrine to nine lean and nine obese young men (ephedrine is sold in 10mg doses). In this study, they gave 170mg of ephedrine for lean subjects and 287.5mg ephedrine for obese subjects. Shockingly, they found that the ephedrine activates BAT in the majority of lean, but not obese people. The really interesting fact is that ephedrine did activate brown adipose tissue in lean individuals whereas in the past scientists did not even know if this was possible in humans. The other startling fact was that it did not work in obese people. So the question is, are obese people overweight because they have the inability to activate brown adipose tissue or is it that they have a defective neurological pathway that activates brown adipose tissue? The good news is that in countries where ephedrine is still legal, it can be a great addition to your pre-contest stack to get shredded as increased activation of BAT is a potent stimulator of thermogenesis. But if you are obese, ephedrine may be a waste of money.

REFERENCE: Snyder, B.J., J Strength Cond Res., 2012 Sep;26(9):2394-400.