Anabolic vs androgenic effects describes the two broad types of activity produced by anabolic-androgenic steroids (AAS). Anabolic effects are tissue-building effects, particularly on muscle and bone. Androgenic effects are masculinizing effects, related to the development and maintenance of male sex characteristics.
The two terms are often used to compare compounds, sometimes using an “anabolic-to-androgenic ratio.” This article explains what each term means, where those ratios come from, why they have important limitations, and why no anabolic steroid produces tissue-building effects without androgenic effects. For an overview of how compounds are classified, see our guide to the different types of steroids and their function.
What do anabolic and androgenic mean?
Anabolic effects
“Anabolic” refers to processes that build tissue. For AAS, anabolic effects mainly include increased muscle protein synthesis, increased muscle size and strength, and effects on bone.
Older research often measured anabolic activity through nitrogen retention, an indirect sign that the body is building more protein than it breaks down. Modern research more often measures muscle size, lean mass, and protein synthesis directly. Our article on building muscle with anabolic steroids explains these mechanisms in more detail.
Androgenic effects
“Androgenic” refers to the development and maintenance of male sex characteristics. Androgenic effects include growth of the prostate and other male reproductive tissues, deepening of the voice, growth of facial and body hair, increased oil production in the skin, and scalp hair loss in people who are susceptible.
In women, androgenic effects appear as virilization, which can include voice deepening, increased body and facial hair, and clitoral enlargement. Some of these changes may be permanent.
Why are both effects linked?
Anabolic and androgenic effects are linked because they are produced by the same receptor. The body has one androgen receptor, and it is present in muscle as well as in the prostate, skin, hair follicles, and many other tissues. There is no separate “anabolic receptor.”
This is why every anabolic steroid also has androgenic effects. Researchers have tried for decades to develop a steroid that builds muscle without masculinizing effects, and none has achieved a complete separation (Kicman, 2008).
If there is only one receptor, why do compounds differ?
Compounds can still differ in the balance of effects they produce, mainly because of how different tissues process them.
Conversion to more potent forms
In some tissues, including the prostate, skin, and scalp, the enzyme 5-alpha reductase converts testosterone into dihydrotestosterone (DHT), a more potent androgen. This amplifies testosterone’s androgenic effects in those tissues. Muscle has relatively little of this enzyme, so this amplification does not occur to the same extent there.
Conversion to weaker forms
Nandrolone is processed by the same enzyme, but it is converted into a weaker compound rather than a stronger one. As a result, nandrolone tends to produce comparatively less androgenic activity in tissues such as the prostate than testosterone does, relative to its effects on muscle (Kicman, 2008).
Conversion to estrogen
Some AAS can be converted into estrogen by the aromatase enzyme, which adds estrogen-related effects such as fluid retention and breast tissue growth in men. Compounds derived from DHT cannot be converted this way. These estrogen-related effects are separate from both anabolic and androgenic effects but are often discussed alongside them.
These differences shift the balance of effects. They do not eliminate androgenic effects.
Where do anabolic-to-androgenic ratios come from?
Anabolic-to-androgenic ratios come mainly from animal testing. In the 1950s, researchers developed a method, later known as the Hershberger assay, that compared how much a compound increased the weight of a muscle called the levator ani with how much it increased the weight of the prostate and seminal vesicles in castrated rats (Hershberger et al., 1953).
The levator ani was used as the “anabolic” marker and the reproductive tissues as the “androgenic” markers. Testosterone was given a ratio of 1:1, and other compounds were rated relative to it.
Why ratios have important limitations
Ratios from these tests are often quoted as if they precisely describe a compound’s effects in people. They have several important limitations.
The muscle used is unusual. The levator ani is a pelvic muscle that is especially sensitive to androgens and is not representative of the skeletal muscles in the arms, legs, and trunk.
Rats are not humans. Differences in metabolism between rats and humans mean results do not translate directly.
The tests were limited. The original measurements involved specific doses, durations, and routes of administration, and they do not capture effects on the heart, liver, lipids, mood, or many other systems.
For these reasons, a compound described as having a high anabolic ratio is not necessarily safer or free of androgenic effects in humans (Kicman, 2008).
Why the difference is often misunderstood
Compounds are often described in gym language as “more anabolic,” “more androgenic,” “mild,” “clean,” or “harsh.” These labels compress a complex balance of effects into a single impression and can create the false belief that a compound produces only one type of effect.
In reality, every AAS acts on the androgen receptor, every AAS has both anabolic and androgenic activity, and every AAS suppresses the body’s natural testosterone production. Androgenic effects are also only one part of the risk picture. Many important risks of AAS use, such as effects on the heart, cholesterol, and liver, are not captured by the anabolic-androgenic distinction at all. Our guide to the key facts about steroids summarizes these broader effects.
Why the distinction matters for women
The difference between anabolic and androgenic effects is particularly important for women, because androgenic effects in women can include permanent changes such as voice deepening.
Compounds marketed as having a favorable anabolic ratio are often promoted as suitable for women, but because no AAS is free of androgenic effects, this does not mean they are free of virilizing effects. Our article on Anavar and female fertility discusses these effects in more detail.
The bottom line
Anabolic vs androgenic effects describes two types of activity that anabolic steroids produce: tissue building, mainly in muscle and bone, and masculinizing effects in tissues such as the prostate, skin, and hair follicles. Both come from the same androgen receptor, which is why no anabolic steroid builds muscle without androgenic effects.
Compounds differ in the balance of these effects, largely because of how tissues convert them into stronger, weaker, or estrogen-like forms. Anabolic-to-androgenic ratios come from rat studies with important limitations and should not be read as precise predictions of effects or safety in humans.
References
Hershberger LG, Shipley EG, Meyer RK. Myotrophic activity of 19-nortestosterone and other steroids determined by modified levator ani muscle method. Proceedings of the Society for Experimental Biology and Medicine. 1953;83(1):175–180.
Kicman AT. Pharmacology of anabolic steroids. British Journal of Pharmacology. 2008;154(3):502–521. Pope HG Jr, Wood RI, Rogol A, Nyberg F, Bowers L, Bhasin S. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocrine Reviews. 2014;35(3):341–375.
