It's the drug of choice for professional athletes who want to create lean muscles and reduce their body fat. Some claim it helps turn back their genetic clocks.

But in WTAE-TV's "Diet A Day" series, Kelly Frey says that finding the fountain of youth in a bottle of human growth hormone is a bad idea.

"A lot of people take (HGH) thinking that it's going to have an anabolic effect in terms of building muscle," Pittsburgh Steelers nutritionist Leslie Bonci tells Frey. "No studies have shown an increase in terms of size and shape associated with using it.

"It actually starts to alter the level of sex hormones in our body. For women, we might be producing more testosterone. For men, more estrogen. This is not a desired side effect for taking these things."

Not only will your sex hormones be out-of-whack, but Bonci says that HGH also causes a tremendous amount of stress on your ligaments, tendons and joints.

Most labels on over-the-counter products carry warnings for people who have certain medical conditions or who are under the age of 18.

"(Taking) anything that is listed as a hormone -- unless somebody has prescribed it -- is absolutely not (a good idea)," Bonci says.