A Complete Guide to Selective Androgen Receptor Modulators

A recent study by Harvard University highlights the importance of strength training to live a longer, healthier life. According to their findings, people who work out regularly stand a 20% less chance of premature death.

Gym lovers, who work out as if their lives depend on it every day, might very well utter, ”I told you so”. Yet, for many of these enthusiasts, their efforts have gone far beyond staying alive.

In many cases, gym culture revolves around appearances more than health concerns. This leads the truly dedicated gym enthusiast to turn to more extreme methods of bulking up.

Selective androgen receptor modulators are one of them. Keep reading to find out more about SARMs and the pros and cons associated with them.

What Are Selective Androgen Receptor Modulators (SARM)?

Steroidal SARMs have been around since the 1940s. At this time, Ligand Pharmaceuticals marketed them as a remedy for cancer, osteoporosis, and more.

Professor James T. Dalton discovered the first non-steroidal SARM by accident while studying potential treatments for prostate cancer in 1998. It came about by modifying the chemical structure of a testosterone molecule.
 His discovery, called Andarine, had little effect on cancer. Yet, the professor noted it did cause significant increases in muscle mass, much like steroids do.

Years later, Professor Dalton used another SARM, Ostarine, in clinical trials for muscle wastage. The results were startling.

Each of the elderly male test subjects gained muscle mass while losing body fat.

Like steroids, selective androgen receptor modulators bind to androgens. In this way, they work to bind muscle fibers and increase muscle mass.

Unlike steroids, they don’t enhance androgenic (male) characteristics.

Selective androgens bind only to some types of receptors in different tissue cells, mostly muscle tissues. Steroids bind to all androgen receptors in the body, causing severe side effects.

In a nutshell, SARMs react naturally with the muscle cells to enhance their development.

What Are the Proven Benefits of SARMs?

There aren’t many conclusive studies on SARMs, but we do know a few things about these substances. Overall, they offer three major benefits, namely:

  • increased muscle mass
  • decreased fat mass
  • increased bone mass

While this might seem ideal for bodybuilders, SARMs are mostly studied in relation to how they can help seriously ill people.

The major benefit of SARMs in medicine is that they are non-aromatized or methylated by the body. Due to this, they don’t harm the liver or convert into other active estrogen or androgen compounds.

Other drugs, like prohormones and anabolic steroids, arouse major concerns about liver toxicity and aromatization.

Another issue with male patients is that compounds that increase muscle mass also increase prostate mass. This can lead to many further health problems. SARMs do not have this effect.

So far, studies involving SARMs have revealed none of the devastating side effects associated with AAS and Prohormones.

These include:

  • prostate cancer development
  • baldness
  • acne
  • excessive body hair growth
  • male breast development
  • high blood pressure
  • poor liver and cholesterol blood panels
  • heart growth
  • elimination of natural testosterone production

Due to these benefits, there are ongoing trials involving SARMs as a treatment for muscle wasting, sports injuries, and age-related muscle atrophy.

Side Effects of SARMs

Although SARMs are a proven safer alternative to anabolic steroids, they aren’t without a few side effects themselves.

Studies suggest that SARMs use has the potential to cause heart attack and stroke. A few isolated cases indicate reduced testosterone production and vision complications in test subjects.

As such, none of the SARMs currently involved in clinical trials have advanced to late-stage levels. This is the part where they undergo human testing to monitor their long-term effects.

Most studies to date involve rats, mainly castrated male rats with elevated LH (Luteinizing Hormone) and FSH (follicle stimulating hormone) levels. These hormones can cause reproductive issues when they’re off kilter.

In the simplest terms, it’s simply too early to tell if SARMs have any serious side effects.

Is SARMs Illegal?

Due to the multitude of uncertainties involving SARMs studies, they remain without the FDA’s blessing for use in prescription medications, or as a health supplement. SARMs are widely banned in sports and on the prohibited lists of several controlling organizations, including the:

  • International Olympic Committee (IOC)
  • World Anti-Doping Agency (WADA)
  • National Collegiate Athletic Association (NCAA)

These controlling bodies believe that SARMs may give athletes an unfair advantage. That’s because of their muscle- and bone-enhancing properties.

As such, SARMs remain banned in all competitive sports worldwide.

However, SARMs aren’t a banned substance and are thus legal under federal law. For now, they’re legal at a state level, too.

So, if you’re wondering where to buy Ostarine and other SARMs legally, you won’t have to look far. It’s not illegal to sell SARMS for research purposes, and many reputable suppliers do.

Types of SARMs

While there are at least 32 different kinds of anabolic steroids available, there are currently eleven well-known types of known SARMs, each with unique traits. These are:


Andarine also goes by the names S-4 or GTx-007. It is an orally active, tissue-selective SARM that simulates the anabolic organs faster than the androgenic ones.

It can increase bone and muscle mass without affecting the prostate, as it doesn’t suppress LH or FSH significantly. Andarine not only binds to androgen receptors 335 as effectively as testosterone, but it still builds muscle mass and strength.

It’s believed that Andarine could help fitness enthusiasts during the fat loss phase by decreasing LPL (a fat-storing enzyme).
 Andarine presents two serious side effects. It can cause temporary night blindness or yellow-tinted vision as well as suppression of the hypothalamus, pituitary gland, and gonads.


Known as MK-2866 or GTx-024, Ostarine is an orally active SARM.

Recently, a 12-week test on this SARM involving elderly men and postmenopausal women had several positive results, including:

  • increased lean body mass
  • improved physical function
  • increased insulin sensitivity

In this light, fitness industry users have their eyes on Ostarine as an ally during the recomposition and bulking phases. Ostarine may offer significant bulking and fat-burning benefits, but it also has side effects.

These include suppression of the HPG (hypothalamus, pituitary gland, and gonads) axis and elevated estradiol levels, which can lead to liver damage, gynecomastia, and hyperthyroidism.


After the discovery of non-steroidal SARMs, Ligand Pharmaceuticals turned their focus to developing orally-active Ligandrol, known as LGD-4033. This SARM has already completed Phase I clinical trials, which involve voluntary human testing.

These tests revealed that humans can tolerate a maximum of 22 mg per day of Ligandrol for up to 14 days. At the same time, the test subjects experienced:

  • decreased fat mass
  • increased strength
  • enhanced feelings of well-being
  • improved lean body mass

Further studies reveal decreased bone turnover rate under laboratory conditions.
 Unlike Andarine, Ligandrol does not require an intra-week cycling protocol. It does not appear to increase LH, FSH, PSA (Prostate-Specific Antigens), or estradiol, either.

However, dosages above 5 mg per day can decrease HDL and total testosterone values. This may lead to headaches, nausea, fatigue, and low libido.


GW-501516, or Cardarine, isn’t technically a SARM, although many people classify it as one.

Instead, it is a selective activator that binds to PPARs (Peroxisome proliferator-activated receptors) instead of androgen receptors. PPARs play a vital role in storing and burning fat, hence the confusion with SARMs.

Cardarine works by activating AMPK, which is an instrumental enzyme for energy homeostasis at a cellular level.

This enzyme oxidizes fatty acids and stimulates muscle glucose uptake. As such, Cardarine shares some benefits with SARMs.
 Researchers noted that Cardarine can help reverse metabolic anomalies in obese pre-diabetic men with metabolic syndrome.
 Further studies involving monkeys revealed that Cardarine may help eliminate diet-induced obesity and Type II diabetes. Additionally, it may lower VLDL (also known as bad cholesterol) and increase HDL (good cholesterol).
 Despite all these pros, Cardarine caused cancer in rats when administered in very high doses. It is also banned by the World Anti-Doping Agency.
 Fitness fans view a low dose of Cardarine as a potential ally for increasing fat loss as well as anaerobic and aerobic endurance.


This is one of the few SARMs that’s advanced to clinical trials thanks to its highly selective properties. It acts only on androgen receptors.

BMS 564,929 doesn’t affect SHBG (Sex hormone-binding globulin), aromatase, or prostate to a significant degree.

It’s in development as a treatment for the age-related functional decline but can produce side effects in some cases. These include depression, reduced libido, and decreased muscle mass, bone density, and muscle strength.


AC-262,356 produces anabolic effects at 66% of the strength of testosterone. As an androgen, its potency is about 27%.

As such, it doesn’t significantly affect the prostate and seminal vesicle weight.
 Studies on rats show this SARM increases muscle mass and LH levels, leading to poorly functioning sexuality. In female rats, it created a sex hormone imbalance.
 These studies show the compound’s potential for increasing muscle mass and hormone regulation.


JNJ-28330835 underwent tests for its potential to decrease prostate weight while increasing muscle mass. However, other studies on lab rats showed it had little effect on the prostate.

In rats with their testicles removed, the compound helped restore lost lean mass quickly. This suggests that JNJ-28330835 may prove useful in minimizing lean mass loss as testosterone decreases with age.

Further complications involved reduced bone turnover in females, i.e., the rate at which the body resorbs and forms bone over time.


LGD-2226 increased muscle mass, improved sexual function, and strengthened bones in lab rats. It had no impact on prostate size. Studies showed that the compound worked by decreasing bone turnover rate while simultaneously increasing bone formation.

Most other treatments and drugs target only one of these pathways.

Earlier research also shows that LGD-2226 increases libido and muscle mass, but there’s still a lot more research needed involving human reactions to this SARM.


Studies involving LGD-3303 show this compound has no negative effects on the androgenic organs, even at high doses. With both oral and continuous infusions, rats showed increased muscle mass.


S-40503 can increase muscle mass and BMD at the same rate as DHT without impacting prostate weight, unlike DHT, which can greatly increase the weight of this gland.
 Studies involving both male and female rates produced decreased bone breakdown in both sexes. There is currently no evidence to suggest that S-40503 may affect muscle mass.


S-23 has a high binding affinity to androgen receptors. Research on rats shows it can reduce fat mass, increase muscle mass, and decrease prostate size.

Non-castrated rats showed decreased LH levels, and significant muscle increases. Researchers view decreased prostate size as a red flag for human applications.
 S-23 also has contraceptive properties when used on non-castrated rats. After 100 days of stopping the treatment, the rats returned to high fertility, producing a 100% pregnancy rate in tests.

This may have important implications for the birth control industry once researchers complete more studies.

Start With the Basics on Your Fitness Journey

Now that you know your way around selective androgen receptor modulators a little better, you’ve probably got a deeper understanding of why they occupy a gray area when it comes to supplementation.

There’s no substitute for a healthy lifestyle, good nutrition, and a disciplined exercise program if you want to increase your muscle power.

Remember, if you decide to experiment with these substances, it’s best to talk to your doctor first. They might have more information about the latest research than what’s available to you.

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