New research suggests that obese people can significantly slow the degeneration of their knee cartilage by losing a substantial amount of weight.

Researchers from the University of California at San Francisco found evidence that weight loss has a protective effect against cartilage degeneration and that a larger amount of weight loss is more beneficial.

According to the Center for Disease Control and Prevention, obesity is a major risk factor for osteoarthritis, a degenerative joint disease that affects more than a third of adults over the age of 60. The knee joint is common site of osteoarthritis and in many people the condition progresses until total knee replacement becomes necessary. Aging baby boomers and a rise in obesity have contributed to an increased prevalence of knee osteoarthritis.

"Degenerative joint disease is a major cause of pain and disability in our population, and obesity is a significant risk factor," Alexandra Gersing, lead author of the study, said in a statement. "Once cartilage is lost in osteoarthritis, the disease cannot be reversed."

For the study, researchers collected and analyzed data from more than 500 overweight and obese patients. They either had mild to moderate osteoarthritis or risk factors for the disease. Investigators analyzed differences in the quality of cartilage among the three groups over a four-year time span.

"Cartilage degenerated a lot slower in the group that lost more than 10 percent of their body weight, especially in the weight-bearing regions of the knee," Gersing said. "However, those with 5 to 10 percent weight loss had almost no difference in cartilage degeneration compared to those who didn't lose weight."

Substantial weight loss not only slows knee joint degeneration--it also reduces the risk of developing osteoarthritis, Dr. Gersing said. Along with moderate exercise, weight loss is one of the primary interventions against the disease.

"It's most helpful if these lifestyle interventions take place as early as possible," Dr. Gersing said.

The findings were presented at the annual meeting of the Radiological Society of North America.