The fountain of youth: Have we finally found it? Maybe, and it's called human growth hormone (HGH). Hailed as the latest and greatest weapon in the arsenal of Hollywood's elite (a report from Vanity Fair last February found that use of human growth hormone injections is widespread within the industry), the theory is that increased levels of HGH can turn back time and promise a better sex drive, fitter body, improved mood, radiant skin, and tons of energy. So how does it work? Read on to find out.

What is HGH?

HGH is produced by the pituitary gland, and it is the hormone responsible for regulating, well, growth! In addition, it regulates body temperature, sugar and fat metabolism, and possibly heart function, according to WebMD. HGH also works in conjunction with collagen to maintain your skin and muscle composition, and since your production of HGH and collagen slow down as you age, your skin becomes looser and thinner. That's where HGH supplements and injections come in: By boosting your sagging HGH levels, you'll feel as though you're in your 20s again—even as you approach middle age.

How do HGH supplements work?

Although proponents of HGH swear by its rejuvenating effects, the hormone hasn't been studied that much, especially in supplement form (most studies have focused on HGH injections). Doctors have been using it for years in children who suffer from abnormal growth problems, and it is sometimes used to regulate blood sugar in diabetics, but even as the use of HGH injections and supplements rises among athletes and celebrities, its legal status remains somewhat ambiguous to most people. In fact, HGH supplements and injections are only legal when prescribed by a doctor, and it's illegal to distribute HGH for any reasons other than medical use, though you can purchase supplements, as most use a synthetic version of the hormone.

Among the other reported benefits of HGH is weight loss. Although the results of a 1990 study published in the New England Journal of Medicine suggested that synthetic injections of HGH led to muscle gain and fat loss, the study was eventually denounced, as most follow-up studies have failed to show the same results.

But there is some promising news: The results of a 2012 double-blind study conducted on a supplement (SeroVital-hgh), which was featured on the internationally famous medical TV show, suggests that a certain combination of amino acids could actually stimulate the body's natural production of HGH, which could provide a natural alternative to injecting synthetic HGH directly into the body. Both male and female subjects given a special blend of amino acids saw a mean increase of more than six times the levels of HGH they started with at the beginning of the study. Subsequent pilot studies also showed that SeroVital-hgh may improve sleep quality and even increase endurance.

The anecdotal evidence also seems promising. Dennis Pelino, a 60-year-old Beverly Hills entrepreneur, told CNN that five years ago, he was having trouble keeping up with the younger people he was doing business with, so he started treatments, which included HGH injections.

"My skin tone got a lot better. I just felt better," he says. "My eyes got a lot brighter. My hearing, I swear, got better." Pelino says HGH injections, along with a healthy diet, exercise, and supplements has made him feel 10 years younger.