Why are anabolic steroids illegal and why is their use prohibited?
In short, any steroid substance that is not on the Designer Anabolic Steroid Act of 2014 which excludes some forms of estrogens, progestins, corticosteroids, and dehydroepiandrosterone providing they are (1) not on the list, (2) do not mimic something that is on the list, or (3) are derived from a plant.
Almost everything that is man-made – synthesized – and that has an anabolic effect is illegal.
Anabolic Steroids and Testosterone
Anabolic steroids are synthesized in a lab with the sole purpose of mimicking naturally produced testosterone. Testosterone is both an anabolic and androgenic hormone.
- Anabolic – muscle growth, bone growth, etc.
- Androgenetic – produces effects that make you manly – facial hair growth, deeper voice, production of sperm, etc.
Anabolic steroids are not supplements even though there is a very large gray area with plenty of overlap. The key difference between an illegal anabolic steroid and a supplement is that an anabolic steroid is considered a drug, whereas, a supplement is considered dietary in nature. In short, a drug is intended for use as a medication and a supplement is intended as an addition (supplement) dietary intake as nutrition.
That distinction is very important and is addressed in the Designer Steroid Control Act of 2014.
” Prohibits a substance from being considered to be a drug or hormonal substance for purposes of such Act if it is: (1) an herb or other botanical, a concentrate, metabolite, or extract of, or a constituent isolated directly from, an herb or other botanical, or a combination of two or more such substances; or (2) a dietary ingredient for purposes of the Federal Food, Drug, and Cosmetic Act and is not anabolic or androgenic. Requires any person claiming the benefit of such an exception to bear the burden of providing the appropriate evidence.” 
The key words in that statement (for the purpose of this article) are … “and is not anabolic or androgenic.” For the most part, plants do not produce anabolic steroids. The production of anabolic steroids requires certain criteria and one of those criteria is cholesterol, which plants do not produce. Still, there are male plants and female plants and to develop those types of characteristic (androgen) you need a steroid of which plants have their own version known as sterols. Sterols do not directly translate into a human compatible steroid though some anabolic steroids for human consumption have a sterol base.
Why is Estrogen Not an Anabolic Steroid?
Estrogen is not considered an anabolic steroid because it does not encourage the growth of muscles. Estrogen, as a term, is also confusing because it means both a single hormone and a family of hormones that, generally speaking, are female in nature. That is not to say that estrogen is not produced in the male body, it is.
Men, however, are less likely to take large quantities of estrogen because it is a female sex hormone and who likes a man with boobs? Estrogen, in high dosages also nullifies testosterone so if your goal is to gain muscle mass, then estrogen is not the hormone to take.
Corticosteroids, in general terms, affect the immune system and generally do not play a part in the anabolic process, at least not enough to be considered an anabolic steroid. We see their use as a treatment for disease and especially in the treatment of diseases that involve inflammation, such as osteoarthritis and in diseases that cause wasting effects, such as cancer and AIDS. In terms of bodybuilding, corticosteroids are going to cause your body to store fat and that is the opposite of what most bodybuilders want.
Progestins are used as birth control products and not anabolic in nature. They are powerful hormones that do not apply to bodybuilding. Also, progestins convert to estrogen and other female hormones. They have the opposite effect of testosterone making them not suitable for bodybuilders.
Dehydroepiandrosterone or DHEA is a prohormone that can convert to both female and male sex hormones – estrogen and testosterone. It is a banned substance for athletes and is recognized by the Olympic Committee as a doping drug. DHEA is a big gray area. It has been on Congress' radar for a while and at some point, may likely make the list of illegal steroids.
What are Legal Anabolic Steroids?
The only way to have an anabolic steroid that is legal is to have a prescription for its use. If you have an anabolic steroid and you do not have a prescription from a medical doctor, then chances are it is an illegal substance. Anabolic steroids are considered schedule III drugs.
When it comes to supplements, they must not claim to accomplish or enhance anabolic features. Any supplement that claims to “cure” is considered a drug and stops being a supplement. This is a situation that occurs many times per year. The FDA has very strict label laws that not demand that a products full ingredients be listed, but also outline what claims can and cannot be made on a label.
In short, anabolic steroids not prescribed by a medical doctor are generally illegal to use and possess. There are gray areas when it comes to prohormones and any use of those should be considered carefully.
 Summary: HR 4771 – 113th Congress (2013-2014) – Congress.gov