In the last two decades, prohormones have also been used by bodybuilders, athletes, and nonmedical users of anabolic steroids and other hormones to refer to substances that are expected to convert to active hormones in the body. The intent is to provide the putative benefits of taking an anabolic steroid without the legal risks, and to achieve the hoped-for benefits or advantages without use of anabolic steroids themselves. However, since prohormones are now listed alongside anabolic steroids themselves, they are classified as illegal and subject to the much tighter regulatory requirements of the Food and Drug Administration (FDA) which apply to prescription hormones. The US Food and Drug Administration moved to halt sales of androstenedione, a dietary supplement marketed as a muscle enhancer that officials said can stunt growth in children's penises and cause problematic sexual changes in adults. "This is a critical part of the FDA's broad crackdown on unsafe dietary supplements," said Dr. Mark McClellan, the FDA commissioner, at a news conference. "While andro products may seem to have short-term benefits, the science shows that these same properties create real and significant health risks." [1]
A typical prohormone is intended to be a precursor of an anabolic steroid like testosterone, which is taken in order to boost the body’s available hormone supply. These precursors are intended to be converted to full, active hormones via an enzymatic process that occurs during metabolism, typically resulting in the addition of whichever atoms happen to be missing from the chemical structure of the compound.
Prohormones are used mainly by athletes looking to increase size, strength, endurance, reduce recovery time or add lean body mass. They are most often used for increasing muscle mass or reducing body fat levels. Life extension groups are also increasingly using prohormones as a means of hormone replacement therapy, as an alternative to prescription drug use.
The use of prohormones has become popular among bodybuilders, since the effects can be similar (though normally much less drastic) to those achieved through the use of synthetic anabolic steroids, including gains in muscular strength and hypertrophy. There are currently many companies manufacturing prohormone products for this purpose.
Prohormones have the same side effects as anabolic steroids, and are dependent upon the user as to which side effects one might experience. Some side effects are acne, hair loss, breast tissue enlargement, and prostate swelling.