Ripp, I have heard that a lot as well.
Lets attempt to set it straight. haha, like that will ever happen.
Marijuana and Testosterone (
Marijuana and Bodybuilding - IllPumpYouUp.com)
A brief report concerning the appearance in gynecomastia in three male pot smokers published in 1972 sparked a number of subsequent studies that examined the relationship between marijuana use and testosterone levels. Gynecomastia, or "male breasts," however, is not a common side effect encountered with marijuana use.
Instead, the condition is usually the result of an imbalance between testosterone and estrogen in men, with something causing an increase in the latter. Since marijuana has no estrogenic activity, it isn't likely to cause this condition.
Even so, animal studies clearly point to an inhibitory effect of marijuana on both testosterone and luteinizing hormone (LH) production. LH is the pituitary hormone that governs endogenous testosterone synthesis in men. When it comes to humans, though, things are far less clear.
Most studies that have examined human marijuana use haven't shown any significant effect on testosterone levels in normal men. A 1983 study, however, did find depressed testosterone levels after subjects smoked just one joint, with the effect lasting 24 hours. A 1984 study found that pot not only inhibited testosterone but also lowered prolactin, thyroid and growth hormone. It did that by altering the expression of brain substances that govern hormone release.
Nevertheless, a 1989 study gave 17 male volunteers both high and low doses of THC and then tested their hormonal responses. The results showed no hormonal or immune parameters affected by either a high or low dose of THC. Notably, both testosterone and cortisol were examined, indicating that pot doesn't produce catabolic effects in muscle through increased cortisol release.
Based on the majority of studies that have looked at the effects of pot on testosterone levels, it appears that the drug has little or no effect on this hormone in humans. One study that examined Jamaican pot smokers, however, did find a significant decrease in active thyroid hormone in the blood, although the men showed no apparent thyroid dysfunction. Significantly, the men also showed normal testosterone levels despite smoking an average of seven to eight joints a day.
Myth: Marijuana Causes Sterility and Lowers Testosterone (
NORML's Marijuana Health Mythology)
Government experts concede that pot has no permanent effect on the male or female reproductive systems.1 A few studies have suggested that heavy marijuana use may have a reversible, suppressive effect on male testicular function.2 A recent study by Dr. Robert Block has refuted earlier research suggesting that pot lowers testosterone or other sex hormones in men or women.3 In contrast, heavy alcohol drinking is known to lower testosterone levels and cause impotence. A couple of lab studies indicated that very heavy marijuana smoking might lower sperm counts. However, surveys of chronic smokers have turned up no indication of infertility or other abnormalities.
Less is known about the effects of cannabis on human females. Some animal studies suggest that pot might temporarily lower fertility or increase the risk of fetal loss, but this evidence is of dubious relevance to humans.4 One human study suggested that pot may mildly disrupt ovulation. It is possible that adolescents are peculiarly vulnerable to hormonal disruptions from pot. However, not a single case of impaired fertility has ever been observed in humans of either sex.
Footnotes
1. Dr. Christine Hartel, loc. cit.
2. NATIONAL ACADEMY OF SCIENCES Report, pp. 94-9.
3. Dr. Robert Block in Drug and Alcohol Dependence 28: 121-8 (1991).
4. NATIONAL ACADEMY OF SCIENCES Report, p. 97-8.
THC and T (
Anabolic Research: Marijuana and Bodybuilding: The Scope on Dope)
The best place to start is with one of the most talked about effects of marijuana— its supposed ability to suppress testosterone. Since testosterone is one of our primary anabolic hormones, suppression of its levels would obviously be an unwelcome effect when it comes to building muscle. We men like testosterone and tend to look for ways to increase levels, not suppress them. If weed is really a hormone killer, it would certainly stand to reason it could kill your gains as well. So where exactly does the research stand in this regard? Is weed really tantamount to smoked castration? There are three studies I want to highlight and I think they do a good job of tying things together.
The first study was conducted in the mid-1980s and involved four healthy male subjects (non-smokers) who were given different amounts of marijuana (one or two joints with 2.8 percent THC) to smoke on two separate days, after which point its effects on hormone profiles (prolactin, FSH, LH, cortisol, testosterone, free testosterone and growth hormone) were measured.1 The effects of this study were fairly clear. In these four cases, marijuana smoking caused a significant drop in LH and a slight, but not significant, drop in FSH, prolactin and free and total testosterone (they remained within normal ranges). GH and cortisol were elevated slightly. These results would lead one to believe that marijuana is a bad thing to do when it comes to testosterone and might not be the best for bodybuilding. However, we must remember that this study involves subjects who don’t regularly smoke marijuana. In our case we want to know what regular smoking will do to you, not just smoking a joint one night at a party, as it would take regular use to interfere with your daily progress.
Our next study shows the effects of regular use. It involved 25 healthy regular male marijuana smokers, whom were all students at the sponsoring university.2 All of the subjects smoked marijuana at least once per week, with an average of approximately 5.1 joints per week each. The researchers here took blood samples from these smokers and compared their hormone profiles to those from a group of 13 similarly-aged, non-smoking control subjects. The marijuana smokers were shown to have levels of plasma testosterone that were normal for their ages and the exact measures weren’t significantly different from the control group. No differences could be observed. The study shows us that the effects marijuana has on hormone levels seem to weaken with regular use. While the occasional user notices some discernable changes in hormone levels, these changes don’t seem to be found in regular users.
Lastly, there was another good study published in 1991 that lets us look at the effects of regular marijuana smoking on hormone production.3 The study has the largest population of participants, with 149 people (93 men and 56 women). The mean age was 23.5 years. The various subjects were stratified into groups depending on their level of marijuana smoking (frequent, moderate, infrequent). About half the subjects smoked no marijuana and served as the control group. When all of the blood work was compared, even chronic marijuana use was shown to have no significant effect on hormone concentrations, in either men or women, when compared to those of non-smoking controls. The bottom line, at least given the research we’ve seen so far, suggests that a single smoking episode might slightly lower certain hormone levels (and may raise others), but that these effects seems to diminish with any type of regular use, such that regular smoking probably doesn’t cause a real and lasting suppression of serum testosterone. If there’s any weak suppression there, it isn’t strong enough to show up with any statistical significance in these studies.
There are just a few articles I've found on the topic.
I agree that it is very controversial and very hard to prove, especially since every study has bias one way or another, every test subject has a multitude of unknown variables and so on and so on..
Please Scroll Down to See Forums Below 
.jpg "Research Chemical Sciences")
.png "Research Chemical Sciences")
