Proponents of the use of HGH as an anti-aging therapy say that the study does not take all available research into account.
"The Liu et al paper is flawed, as it is based on an incomplete compilation of clinical studies of HGH replacement in healthy adults," said Dr. Ronald Klatz, president of the American Academy of Anti-Aging Medicine (A4M), in a statement issued Monday.
"The A4M submits that thousands of published studies on hundreds of thousands of patients have demonstrated the clear benefits of adult GH replacement therapy, when utilized under proper clinical guidelines and at proper physiological dosages."
Among these studies, the A4M maintains, are those showing that normal, healthy adults taking HGH experienced increases in lean muscle mass, decreases in fat mass, increases in bone density, and a host of other health benefits.
Liu's review showed that positive changes in body composition occurred with HGH use.
"We found examples of how fat mass decreased on average a little over 4.5 pounds, and lean body mass, or muscle, increased by about 4.5 pounds," Liu said.
"But we did not find any other clinically important outcomes that changed."
Vance says this relatively mild benefit is far outweighed by the potential for adverse side effects.
"When you're using a drug that costs that kind of money with the side effects that it has and the potential to cause the growth of cancer, I think that the risk outweighs this benefit," she said. "Even though body composition changes occur -- we expect that -- this has not been shown to translate into any functional benefit or longevity benefit."
"Changing body composition does nothing for cardiovascular fitness. Exercise and improved dietary regimens are much more beneficial."
Still, anti-aging proponents say that HGH supplementation is critical in aging adults -- particularly considering that levels of the hormone in the blood tend to decline with age.
"To deny the benefit of HGH and other essential hormonal regulators of metabolism in deficient patients based on age may be considered a heinous act of malpractice which will prove to be erroneous and shortsighted in the years to come," reads the A4M statement.
"In the future, the replacement of essential hormones that decline with age may be seen as important as insulin replacement in diabetics today."
For those unwilling to pay for off-label HGH -- or risk its side effects -- there are a few old-fashioned anti-aging tips that can accomplish the same body composition changes seen with the hormone, Liu says.
"If you think about what people are paying, which is in the hundreds to thousands of dollars, if they were able to go out and exercise or get a personal trainer, they could probably attain those types of changes with regular exercise," he said.
"We should do the things that our moms and doctors tell us to do: Eat well. Exercise. Drink only moderately. Don't smoke, and get enough sleep."