Choosing a Selective Androgen Receptor Modulator: What You Should Know

According to research from Harvard, strength training can contribute to longevity and help you avoid health issues like cancer and heart disease. So, hitting the gym hard is a great idea for health enthusiasts committed to their welfare.

Watching your body transfer into a superhero-like form can also become addictive as you become stronger. For this reason, many people who practice weight training often shift their focus to muscle growth rather than good health.

If you’re at this point, you’re likely wondering if a selective androgen receptor modulator could help your cause. Keep reading to find out what SARMs are and what we know about their effects on the human body.

What Is a Selective Androgen Receptor Modulator?

Like prohormones and steroids, SARMs belong to the class of synthetic drugs that affect hormone levels in the human body. While SARMs aren’t steroids or prohormones, they mimic the action of testosterone in a similar way.

Steroidal SARMs have been around since the 1940s, but James T. Dalton only discovered SARMs during his research into prostate cancer treatments.

During the course of his work, Professor Dalton found out how to modify the chemical structure of a testosterone molecule, using the chemical Andarine.

He never discovered a cancer cure for his efforts, but he did discover that Andarine impacted muscle mass in the same way steroids do. However, Andarine didn’t seem to produce the same side effects associated with steroids.

Armed with this information, he redirected his studies toward finding a cure for muscle-wasting disease.

A few years later, he found out that Ostarine had much the same effect, except Ostarine also helped burn body fat.

Since then, research has revealed ways to use SARMs for treating serious conditions. These include osteoporosis, cancer, and multiple sclerosis, along with muscle-wasting disease.

SARMs vs Steroids

SARMs bind to specific androgen receptors in tissues like bone, fat, and muscle.

They selectively inhibit or activate some biological processes. These include fat loss, cognitive functions, muscle growth, and bone density.

For instance, SARMs that link to androgen receptors increase overall nitrogen retention and trigger protein synthesis. This effectively tricks the muscles into bulking up faster than they would normally.

Steroids are an anabolic compound, which means they aren’t targeted in this way. They bind to all the androgen receptors in the body.

This non-specific action is what causes the negative side effects associated with steroid use, including:

  • Acne and cysts
  • Cancer
  • Enlarged prostate
  • Erectile dysfunction
  • Gynecomastia
  • Increased blood pressure
  • Liver disease
  • Male characteristics in women
  • Raised cholesterol levels
  • Mood swings and aggression

With prolonged use, steroids negatively affect testosterone production. This causes the testes to shrink.

Attempting to manage the side effects of steroids with extra medication only place the liver under more strain, creating even more problems for steroid users.

SARMs haven’t been around for as long as steroids, so we don’t know as much about them. Preliminary studies suggest that SARMs may have the following side effects:

  • Heart attack and stroke
  • Reproductive issues
  • Reduced testosterone production
  • Vision complications

Despite these findings few studies have progressed to the stage where the results are conclusive, never mind high-level human-testing stages. most of the knowledge gained stems from research on laboratory rats.

The bottom line is that it’s too early to identify any side effects caused by SARMs with any certainty. That’s why the FDA is cautious on matters surrounding SARMs.

Legalities Surrounding SARMs

The FDA does not condone using SARMs for anything but research. So, you can’t use them as recreational drugs and supplements, or get a prescription for them, no matter what your gym buddies say.

SARMs use is widely banned in competitive sports and included on the banned substances lists of several sports authorities. These include:

These organizations are adamant that SARMs give athletes an unfair advantage in competitive sports, which only serves to suggest that SARMs do improve bone and muscle strength.

Despite these misgivings, you can buy SARMs legally online, although they’re intended solely for research purposes involving non-human subjects.

What Does Research Reveal About Different Types of SARMs?

Despite the FDA’s misgivings, many bodybuilders have resorted to using SARMS as a muscle drug to build muscle and burn fat. This means there’s now a host of anecdotal evidence to back up the preliminary body of research.

This is what we know about the different types of known SARMs and how they interact with the human body. These are the best-known SARMs as well as some you may never have heard about.


Andarine is an orally active, tissue-selective SARM. It also goes by the names, GTX-007 and S-4.

This SARM targets anabolic tissues rather than androgenic ones, and doesn’t bind to androgen receptor 335 as well as testosterone does.

Despite this, it still works well to grow muscle and increase strength. It doesn’t affect the prostate gland as it doesn’t suppress LD or FSH much.

These findings suggest that Andarine can help decrease lipoprotein lipase (LPL) which stores fat and assist with fat loss.

Andarine has three serious known side effects, namely.

  • Night blindness
  • Temporary vision disturbances
  • The pituitary gland, gonad, and hypothalamus suppression
  • Suppresses natural testosterone production

Some users also experience depression when using this SARM.


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

It’s one of the few SARMs that has undergone human testing. These studies, involving elderly men and postmenopausal women revealed some pleasing results, like:

  • Improved physical function
  • Increased insulin sensitivity
  • Increased lean body mass

These outcomes brought Ostarine to the attention of bodybuilders interested in boosting the bulking and recomposition phases of their training.

It’s still not a legal option though, largely due to the following side effects discovered during the tests. These are:

  • HPG Axis suppression
  • Raised estradiol levels

The HPG axis comprises the hypothalamus, pituitary gland, and gonads. Suppression of the HPG axis, when combined with excess estradiol, can cause the following serious side effects:

  • Gynecomastia
  • Liver damage
  • Hyperthyroidism


Cardarine isn’t technically a SARM. It’s a selective activator that acts in the same way SARMs do. It’s also called GW-501516.

It activates AMP-activated protein kinase (AMPK), a fuel-sensing enzyme that is present in mammalian cells. AMPK oxidizes fatty acids and stimulates glucose uptake in the muscles.

Cardarine gets this process started by binding to PPARs (Peroxisome proliferator-activated receptors) which burn fat using AMPK. Due to this, Cardarine can help reverse metabolic anomalies in obese pre-diabetic males with metabolic syndrome.

Tests on monkeys revealed positive results when using Cardarine as a treatment for Type II diabetes, as it eliminates diet-induced obesity.

One of the major benefits of Cardarine is that it increases HDL (good cholesterol), and lowers VLDL (bad cholesterol).  Cardarine did reveal one serious side effect during laboratory tests. Very high doses cause cancer in rats.

Although using low-dose Cardarine is technically a good way to slim down, it’s also illegal and banned by most sporting bodies around the globe.


Ligand Pharmaceuticals, a pioneer in SARMs research, makes Ligandrol, also called LGD-4033.

This SARM has already completed Phase I clinical trials with voluntary human testing. During the trials, volunteers took 22 mg of Ligandrol every day for 14 days.

Researchers noticed the following bodily changes in all the participants:

  • Decreased fat mass
  • Better lean body mass
  • Greater strength
  • Enhanced feelings of well-being

Further studies in the laboratory revealed decreased bone turnover in the volunteers, too.

Unlike Andarine, Ligandrol works without an intra-week cycling protocol. It doesn’t increase the following either:

  • FSH
  • LH
  • Estradiol
  • PSA (Prostate-Specific Antigens)

Dosages exceeding 5 mg per day can increase HDL and total testosterone values leading to headaches, low libido, nausea, and fatigue.

Numbered SARMs

While investigating various SARMs, you might come across those that have names instead of numbers. These are the more obscure SARMs that haven’t been as extensively tested as the big four mentioned above.

These are the ones that have undergone testing:


This is one of the better-known obscure SARMS and also goes by the name Testolone. RAD140 has a selective action and few known side effects.

These include:

  • Nausea
  • Mood swings
  • Liver complications

Additionally, RAD140 may create a need for PCT to suppress sex hormones.

Testolone acts as a “protective shield” for the muscles. It helps prevent wear and tear during extreme workouts and has shown promise in tests related to treating osteoporosis and muscle wasting.

RAD140 is an oral chemical and does not require the use of needles and syringes.


BMS-564,929 is extremely specific. It acts only on androgen receptors and is one of the few SARMs that’s undergone trials with human subjects.

It doesn’t affect the following to any significant degree:

  • Aromatase
  • Sex hormone-binding globulin (SHBG)
  • The prostate

BMS-564,929 is currently in testing as a possible treatment for age-related functional decline. Some side effects associated with this SARM are:

  • Decreased bone density
  • Depression
  • Reduced muscle mass and muscle strength
  • Reduced libido

As such, BMS-564,929 is of much interest to the medical profession although it holds no significant benefits for bodybuilders.


JNJ-28330835 did not affect the prostate of rats involved with testing for its potential to increase muscle mass while decreasing prostate weight.

Castrating the rats led to significant gains in lean muscle mass, although few people will make this sacrifice in the name of muscle gains.

Despite these extreme measures, this finding does reveal a potential for minimizing muscle mass losses during age-related testosterone decline.

These tests also revealed another complication in that they reduced bone turnover in female rats. That means it reduced the body’s ability to resorb and form bone over time.


Likewise, when tested on lab rats, LGD-2226 did not affect prostate size. It did show improved sexual function, stronger bones, and increased muscle mass in the lab rats.

During the studies, researchers also discovered that LGD-2226 decreased the bone turnover rate while increasing bone formation. Most chemicals only work on one of these pathways.

Previous studies investigated LGD-2226’s ability to boost libido and muscle mass, but this SARM still has a long way to go before it reaches a stage that’s safe enough for human testing.


AC-262,356 has a potency of about 27% and is around 66% as effective as testosterone for producing anabolic effects.

It has no significant effect on the seminal vesicle and prostate.  Studies on lab rats revealed that AC-262,356 increases muscle mass and LH levels and muscle mass, but reduces sexual function. In female rats, it created a sex hormone imbalance.

While these are negative side effects they do reveal a potential for using this SARM to regulate hormones in females.


RU58841 was initially investigated as a topical treatment for acne, androgenetic hirsutism, and alopecia. It’s highly effective for promoting hair growth and reversing male pattern baldness.

RU58841 increases the replication rate of the hair’s outer root sheath cells and prevents DHT from triggering hair loss.

Further studies might reveal a use for this SARM in the realm of hair loss treatments.


S-23 binds very well with androgen receptors. Tests show that it reduced fat mass and prostate size in lab rats, and increased muscle mass.

Unfortunately, decreased prostate size can indicate a shortage of androgen in human applications, which is a red flag for medical professionals.

S-23 also lowered LH levels in castrated rats and produced significant muscle increases. In non-castrated rats, it had a contraceptive effect.

After ceasing treatment, the infertile rats became sexually productive within 100 days. These findings are of interest to the birth control industry.

Buyer Beware

While it’s legal to buy any selective androgen modulator online or elsewhere for research purposes, you should never take any supplements without consulting your doctor first.

You don’t need a prescription to get your hands on SARMs but your doctor can best advise you on any potential issues regarding these substances.

Good health begins with the basics: browse our blog for more information on staying in shape and safeguarding your well-being.