Caffeine

Caffeine is one of the most common ingredients in weight loss supplements. It is claimed to speed up metabolism and help the body burn fat a faster rate. One the other hand, quite a few overweight people drink coffee heavily without any apparent affect on their weight.

What does the science say? In short, studies indicate that caffeine alone does not produce any more weight loss than the placebo. However, the picture is somewhat complicated. At least in the short term, caffeine does increase the metabolic rate and accelerate fat burning. The fact that caffeine nonetheless fails to produce weigh loss may be due to one of the following factors: it seems to increase appetite; it may increase insulin resistance; its metabolic boost may be too short-lived to make a difference.

Whatever the reason, caffeine taken alone does not seem to help lose weight. However, the situation seems to be different when caffeine is combined with ephedrine and possibly certain other active ingredients. Several studies demonstrated that a combination of caffeine and ephedrine produces a short-term weight loss and appears to be more effective than caffeine or ephedrine alone.

Unfortunately, the use of caffeine and ephedrine combination also presents problems. Ephedrine is a powerful stimulant that can produce a variety of side effects and, most importantly, cardiovascular side effects, including increased blood pressure, elevated heart rate and irregular heart beat. In some relatively rare cases, such side effects may reach dangerous levels (see our ephedrine article). As a result, ephedrine was banned as an ingredient in over-the-counter formulas in the US. Even thought the ban has been challenged in courts, ephedrine and ephedra remains in legal limbo. Furthermore, since caffeine is also a stimulant with cardiovascular effect, it may conceivably augment the side effects of ephedrine.

See also the index of studies related to caffeine.