Ephedrine is a great pretender. It mimics effects of the stress hormone adrenaline (epinephrine) which is released by adrenal glands into the bloodstream. Naturally, this is the body's response Tao danger: it triggers the "fight or flight" syndrome and targets many tissues of the body, including those of heart, muscles and fat mobilizing them to face and manage the danger. Ephedrine elicits pretty much the same set of bodily reactions, causing an increase in heart rate, blood pressure, heat production and fatburning.
One positive thing about ephedrine is that the body can adapt to its negative effects while continuing or even enhancing the fat-burning response. Because of its stimulating effect on muscle tissue, ephedrine also helps preserve muscle mass during weight loss on a calorie-restricted diet.