There's a new (old) anabolic steroid that's been making its rounds in the bodybuilding scene recently. People are reporting gains of up to 20lbs in as little as 6 weeks.
Bodybuilders in their crude chemistry language calling it a mix of "tren and test," arguably two of the most effective and fan favorite steroids ever used.
Related - Clenbuterol: The Dark Side of Fat Burning
So, what is this remarkable compound? It goes by the name of MENT or trestolone and has been made widely available thanks to research chemical suppliers. This article will discuss the history, chemistry, and application of trestolone and why it's slowly gaining notoriety and popularity.
The Rise of MENT - Trestalone
MENT (7alpha-methyl-19-nortestostrone), or trestolone was one of several 19-nortestosterone derivatives to be investigated as a possible male contraceptive therapy due to its unique chemical properties. Initially, drug companies were combining progesterone with testosterone in order to produce a viable male contraceptive option due to progesterone's ability to suppress spermatogenesis.
While testosterone can decrease sperm production, the dose for a test-only birth control would be too high to avoid unwanted side effects.
Testosterone can also convert to DHT via 5alpha-reductase, it can have deleterious effects on the prostate, as well as increase male pattern balding. 
Since MENT was incapable of binding to 5alpha-reductase and thus cannot convert to DHT, it made it a perfect candidate for an androgen male contraceptive.
The reason for this lies in the unique alpha methyl group on carbon 7 of the molecule. This methyl group sticks out below the steroidal ring structure and sterically inhibits conversion to DHT. However, MENT still can undergo aromatization and undergo other androgen-dependent functions, making it effectively act like testosterone
in the body despite being a 19-nortestosterone derivative. 
MENT was also shown to have minimal affinity for the progesterone and mineralocorticoid receptors, despite being a nandrolone derivative. 
Another unique property of MENT's 7alpha-methyl group is it also can inhibit binging of MENT to sex hormone binding globulin (SHBG), a protein that binds with androgens (and estrogen) so that they can no longer bind to the androgen receptor. If you have ever gotten your testosterone levels check, you will see 2 values: total and free testosterone.
Free testosterone is the amount of testosterone that is NOT bound to SHBG and is "free" to bind to the androgen receptor and elicit its effects. By MENT not being able to bind to SHBG, it is essentially free to only bind to the androgen receptor and yield the benefits of exogenous androgen use. This makes MENT a very attractive option when looking to not only add quality muscle, but also keep your sex drive high and not make any unwanted babies.
What does the research say about MENT? Well, it's actually quite impressive. In a 1992 study in rats investigating the pharmacology of MENT, researchers found the anabolic potency of
MENT to be 10X greater than that of testosterone, while also being 12X more suppressive on HTPA.
This means that if your average male produces 4-7mg of testosterone daily to keep muscle mass and sexual function, only 400-700mcg of MENT is needed to produce the same results.
In this same study, MENT acetate was used to determine the rate of hydrolysis of the acetate ester and how quickly elevated MENT plasma levels were reached. The half-life is also VERY short, calculated to be only 40 min for the unesterified compound (not the acetate, which should extend the half-life slightly). 
A very comprehensive human study was conducted on male subjects that compared the effects of MENT to testosterone, both accompanied with the progestin etonogestrel, on spermatogenesis, as well as sex drive and safety biomarkers associated with androgen use. This was a robust study, containing 29 subjects tested for 48 weeks.
Participants either received two implant pellets each containing 135mg of MENT acetate calculated to release 400mcg daily, or 3 600mg testosterone pellets, with one given every 12 weeks (both groups received 68mg of etonogestrel). Both groups caused significant reduction in sperm production, with 80% of both groups going from an average of 55 x 106/mL to just 1 x 106/mL after 12 weeks of supplementation.
Recovery period was 16 weeks for the MENT group which increased to over 20 x 106/mL, whereas the testosterone group still had azoospermia until after 28 weeks.
As far as safety data, LH and FSH levels were profoundly suppressed in both groups, with FSH dropping 91% and LH dropping 90% in the MENT group. HDL levels dropped 14%, and total triglycerides increased by 13% in the MENT group after 4 weeks.
There was also a significant rise in systolic blood pressure in the MENT group, but returned to normal post therapy. There were no significant increases in hematocrit or hemoglobin in the MENT group, which is often associated with elevated androgenic levels.
This study clearly shows that MENT is a safer and more effective form of male contraception compared to testosterone. The takeaway from this study would be that MENT seems to be fairly safe on lipids and other biomakrers, but definitely needs a PCT to restore LH and FSH levels to normal. 
One of the main side effects from MENT is aromatization. MENT converts into the very potent estrogen 7a-methyl estradiol.
Since MENT and this estrogen both contain the 7alpha methyl group which does not bind to SHBG, it is safe to assume that this estrogen will be active and readily bind to the estrogen receptor, causing water retention and gynecomastia. It is strongly recommended that an aromatase inhibitor like arimdex or letrozole be used when taking MENT.
My Final Thoughts on Trestalone
On paper, MENT looks like an amazing synthetic androgen that is highly anabolic, slightly androgenic while still able to maintain an elevated sex drive despite being a 19-nortestosterone derivative. I don't think it is "10X more hypertrophic than testosterone," but it is very anabolic and I have noticed great gains while following a ketogenic diet
After four weeks of MENT acetate, taking 50mg EOD, you can expect to see a very elevated sex drive, This is typically unusual for many taking 19-nortestosterone compounds, suggesting that MENT does not bind to SHBG.
Appetite should be extremely elevated, and you should see a slight increase in gym strength. 1.25mg of letrozole EOD will combat the conversion to 7a-methyl estradiol, so bloating is minimal.
This appears to be a decent compound for people looking to add good size, while easily combating side effects, as it is safer on your lipids than most other compounds, especially orals.
A PCT will be absolutely mandatory (unless you are on TRT), as this compound was made to heavily suppress LH/FSH. As far as stacking goes, I would pretty much say you can stack this with anything, depending on your goals. I would start at 50mg EOD, with some people going up to 100mg EOD. I can only imagine the gains on 300-400mg/week.
1) Walton, Melanie J., et al. "7??Methyl?19?Nortestosterone (MENT) vs Testosterone in Combination With Etonogestrel Implants for Spermatogenic Suppression in Healthy Men." Journal of andrology 28.5 (2007): 679-688.
2) Anderson, Richard A., et al. "Evidence for tissue selectivity of the synthetic androgen 7?-methyl-19-nortestosterone in hypogonadal men." The Journal of Clinical Endocrinology & Metabolism 88.6 (2003): 2784-2793.
3) Sundaram, Kalyan, Narender Kumar, and C. Wayne Bardin. "7?-Methyl-nortestosterone (MENT): the optimal androgen for male contraception." Annals of medicine 25.2 (1993): 199-205.
4) Liu, Aijun, Kathryn E. Carlson, and John A. Katzenellenbogen. "Synthesis of high-affinity fluorine-substituted ligands for the androgen receptor. Potential agents for imaging prostatic cancer by positron emission tomography." Journal of medicinal chemistry 35.11 (1992): 2113-2129.
5) Kumar, Narender, et al. "Pharmacokinetics of 7??Methyl?19?nortestosterone in Men and Cynomolgus Monkeys." Journal of andrology 18.4 (1997): 352-358.
6) Walton, Melanie J., et al. "7??Methyl?19?Nortestosterone (MENT) vs Testosterone in Combination With Etonogestrel Implants for Spermatogenic Suppression in Healthy Men." Journal of andrology 28.5 (2007): 679-688.