The desire to try growth hormones is common among many guys these days - bodybuilders or not. It is a huge temptation to try
substances that may help in the quest for more muscle and less fat. The urge to experiment with drugs is understandable, but
I can't caution you strongly enough to carefully consider the pros and cons before jumping on the bandwagon.
Athletes and scientists don't see eye-to-eye concerning the muscle-building effects and safety of GH (a.k.a. somatotropin). In fact, athletes themselves appear divided on GH's ability to enhance muscle growth. There's limited scientific evidence showing that GH administration in humans causes increased muscle mass beyond what training alone can produce. This discrepancy arises from the fact that scientific studies conducted to date have used different subject populations, various exercise protocols and dissimilar dosages of GH. From an athletic standpoint, the most important variable yet to be tested is the use of doses of the drug that are higher than those normally prescribed for medical conditions.
This lack of understanding about GH and muscle can be illustrated by the Underground Steroid Handbook by Dan Duchaine. In the first edition (1982), Duchaine stated that HGH (human growth hormone) was the ultimate anabolic substance and, therefore, the most sought-after drug for muscle enhancement. But in his book's sequel. The Underground Steroid Handbook II (1989), Duchaine rescinded this claim and wrote that GH was worthless for athletes. This clearly illustrates the confusion about GH in the athletic world, even among drug gurus.
I interviewed several elite athletes while researching your question. About half of them said they got dramatic effects from using GH; the other half thought GH was a complete waste of time and money. Despite this disagreement, all of the bodybuilders interviewed did believe that GH had a fat-burning, or lipolytic, effect.
In fact, the lipolytic actions of GH are well documented in medical literature, supporting the athletes' opinions. There is evidence that GH plays a major role in bodyfat levels for normal individuals and in those with certain medical conditions. GH, without question, can shift muscle metabolism away from glucose to burning fat for fuel. It appears to do this via several mechanisms: 1) by potentiating the effects of other lipolytic agents such as epinephrine, 2) by activating hormone-sensitive lipase and 3) by directly inhibiting glucose metabolism.
The best examples of the ability of GH to change body composition and metabolism are individuals with untreated acromegaly (a serious medical condition in which a person's body produces too much GH). Left untreated, these people show increases in body-weight, fat-free mass and body-water content, while their bodyfat is greatly reduced. Interestingly, despite having greater muscle mass than normal individuals, untreated acromegalics don't have stronger-than-normal muscles. This could be an important factor for power/strength athletes to consider, since this drug might be of little or no benefit to them. However, it wouldn't be a concern for an athlete seeking to enlarge his/her muscles without regard to strength.
The scientific literature shows that GH does have anabolic actions in skeletal muscle, but how much muscle mass is actually gained remains to be seen. Furthermore, the direct and indirect effects of GH and the somatomedins, insulin growth factor-l and -II (IGF-I and -II), on muscle metabolism are not thoroughly understood. Essentially, athletes are in uncharted waters when they use high doses of GH for muscle building.
Animal studies conducted thus far provide interesting results on the GH/ muscle debate. Investigations on rats have demonstrated that impaired growth resulting from surgical removal of the pituitary gland can be reversed with the administration of GH. It's also possible that exercise-induced muscle hypertrophy in humans may result in part from a natural increase in GH secretion.
Before you go on a GH shopping spree, read this: There is evidence that GH is not a major factor in muscle growth. In a classic 1967 investigation, the effects of GH on muscle development in animals were studied using a model called compensatory hypertrophy (this is the most common animal model used by scientists to analyze muscle growth). It involves taking out a rat's calf muscles and leaving the plantaris muscle intact. By doing this, scientists are essentially taking out 80% of the animal's lower-leg mass. (Ouch!)
The result is that the plantaris must compensate for the missing muscles and subsequently grows like crazy.
The 1967 research looked at normal rats undergoing this surgery and rats that had had their pituitary glands surgically removed before undergoing the same procedure. Surprisingly, no differences were seen in the rate and amount of hypertrophy between the two groups, demonstrating, at least in this study, that GH is not really necessary for skeletal muscles to grow.
Current data suggests that short-term GH or IGF-I treatments can modestly increase nitrogen retention and possibly also the size of muscle tissue. Resistance to the anabolic actions of GH appears to occur after long-term administration (about one month). To complicate things further, most athletes who use GH do so in conjunction with androgens and other protein anabolic substances. No one really knows how effective this stuff is in well-trained young athletes.
The best dosages, if any, for GH have yet to be determined for athletes. Side effects like visceral megaly (enlarged or distended midsections) and altered facial structure have occurred in people who have taken growth hormone. There's still much to be learned about safely optimizing the anabolic actions of GH and about the interactions between this substance, IGF-I, various binding proteins and other growth factors.
Don't be lured into the drug world. The FDA recently approved GH for use in adults deficient in it, and the substance can be transported legally into the United States from other countries (with a prescription), but it is still potentially harmful.