In this lesson you will learn what prohormones are, what they do and what the side effects are. Prohormones (pro-steroids) are substances that are precursors to hormones. So instead of consuming the actual steroid, you consume a substance that turns into an anabolic hormone when it is digested. (an enzymatic process turns prohormones into a anabolic steroids) For a long time prohormones were allowed in sports. But when the american baseball player Mark McGuire announced that he had used the prohormone Androstendione, prohormone supplements started attracting more attention. Before they were banned in 2005, people thought they were innocuous performance enhancers like creatine or whey protein. Now prohormones are listed alongside anabolic steroids and its use is illegal. However, some actors, wrestlers and bodybuilders who don't care about their health and obviously don't plan to compete in events were blood tests are the order of the day still use prohormones. Find information about sports nutrition and drug abuse in sports at nutrition main. Because the effects of prohormones are similar to those achieved through synthetic anabolic steroids, prohormones are very popular among bodybuilding and strength sports.