Anabolic Steroids: Any of a group of synthetic derivatives of testosterone that promote muscle and bone growth. They are classified as a group of performance enhancing or ergogenic drugs. They can be taken either orally or by injection (intermuscualr). It must be stated that it is usually the oral type that carry most of the more serious Side Effects. Testosterone is a natural male hormone that is both anabolic (growing)  and androgenic (masculising).  Anabolic steroids are designed to mimic the growing stages of the body's own testosterone but also designed to try and reduce the masculsing effects. They work by binding with the androgen receptor sites which in turn allows for a greater increase in protein synthesis, thus allowing for greater and more rapid muscle growth. It is vital that when taking steroids for personal benefit that the user not only follows an intense training porgram but also increases protein intake. One of the reasons people grow much quicker while on steroids is that they allow the body to recover and recuperate far quicker than people who are not using and have to solely rely on there body's own natural recovery ability. Cycles: Many who are familiar with anabolic steroids will know that cycles are used so as not to cease the body's own testosterone production indefinetly. A cycle usually lasts between 6 and 12 weeks, it is however, not uncommon for the weary user to use cycles as short as 4 weeks and the experienced user going up to 16 weeks. Once a cycle is completed the user will usually stop for a period of anywhere between 4 weeks and upwards to allow their own testosterone levels to restore themselves. If they did not do this it is very likely that the body will shut down its natural production. Losses Of Weight Gained While On Steroids & Why It Happens: Cortisol is a catabolic (muscle destroying) hormone, and is found in all humans, it is especially found in high levels when the body is under stress.Cortisol also competes for the same receptor sites as testosterone. Now what happens when someone is using an outside source of testosterone is that there is a far greater ratio of test than there is of Cortisol and as a result the test ends up occupying all the receptor sites. When a cycle is ended it is usually a few weeks before the body's own production of test starts to kick back in, now all those catabolic hormones that were competing for the receptor sites are still in your body and have multiplied rapidly cause they have not had the chance to bind with any of the receptors. Now howveer the receptors are free because the cycle has ceased and the body is not yet fully producing its own test. All of these catabolic hormones will now bind to the receptor sites and are eating away at the muscle that was gained while using. The End Result Is A Rapid Decrease In Muscle Mass That Was Gained While On Anabolic Steroids. The good news for users at the end of a cycle is that there are other drugs to help kick start your own test production much quicker than it is usually done. The End Result Is Not As Much Of A Loss As Expected. Stacking: Using a combination of anabolic steroids to maximise the effects. For example if on a bulking cycle stascking Dianabol with Deca would allow for better results than the sum of both if taken seperately. There is no medical evidence to support this but bodybuilders have been doing it for decades and you dont seem to hear complaints from them.