Selective androgen receptor modulators also known as SARMs are currently a popular "under" the counter form of supplements. They are gaining a lot of popularity in the fitness community, especially amongst bodybuilders and young fitness enthusiasts. That’s actually alarming considering that SARMs aren't currently approved for human consumption here in the United States, they can easily be purchased at many supplements stores and even online.
The more popular ones are . . .
- MK-2866 or GTx-024 (Ostarine)
- LGD-4033 (Ligandrol)
- GSX-007 or S-4 (Andarine)
- GW-501516 (Cardarine)
SARMs are commonly marketed as a safer and almost side effect free alternative to steroids. However, lots of the research done on SARMs has been conducted on cancer patients to prevent muscle wasting rather than for bodybuilders trying to gain muscle. According to the FDA, SARMs can increase the risk of heart attacks and strokes and can be highly liver toxic due to them being orally ingested. Also, there hasn't been enough research done on SARMs to know the long term side effects. Lastly, since SARMs are technically a dietary supplement, their nutritional labels are many times inaccurate and sometimes completely wrong due to the fact that dietary supplements aren't regulated by the FDA as they are not considered pharmaceutical drugs.
To sum everything up, I would tell anyone looking into SARMs to steer away from them as they aren't extensively researched when it comes to a bodybuilding perspective and they aren't regulated by the FDA. If you're trying to aid your workout performance and enhance your physique with the help of supplements I'd just stick to the basics such as creatine, pre workout and whey protein.