A Stanford University School of Medicine meta-analysis of clinical studies on the subject published in early 2007 showed that the application of GH on healthy elderly patients increased muscle by about 2 kg and decreased body fat by the same amount.  However, these were the only positive effects from taking GH. No other critical factors were affected, such as bone density, cholesterol levels, lipid measurements, maximal oxygen consumption, or any other factor that would indicate increased fitness.  Researchers also did not discover any gain in muscle strength, which led them to believe that GH merely let the body store more water in the muscles rather than increase muscle growth. This would explain the increase in lean body mass.
The new study examined recent stretch marks and found that they had a higher density of hormone receptors than normal skin, and estrogen appeared to be the most concentrated. Since estrogen is involved in skin healing, that could represent the body’s attempt to heal the injured skin tissue. From the standpoint of steroid users, the greater number of estrogen receptors in stretch marks could also represent a defense against the high level of androgens, which interfere with skin healing. That latter part, however, is strictly speculation. What is known is that stretch marks have a higher density of hormone receptors than normal skin.