This means that the consumer has no way of knowing exactly what is in each substance, or how much of the desired chemical is there. While these products may appear to produce weight loss, the effect is neither real nor permanent and may be dangerous. Many of the products simply speed up the heart rate or cause you to excrete more water. The most common active ingredient of these products is either caffeine or ephedrine, or a combination of both. Caffeine can act to imitate the effects of speeding up the metabolism and thus make it appear to cause weight loss.
Ephedrine causes the body to lose water.
In either case, the body may be subjected to increased heart rate combined with changes in blood pressure. One of the more prominent of these is a molecule called pyruvate. The claims are incredible, as is the price. You couldn't possibly take enough in pill form to have any real effect on your metabolism. If you could, your body would simply convert the pyruvate to fat.