Losing a large amount of weight slows the loss of knee cartilage in obese people, a new study shows.

Obesity is a major risk factor for knee osteoarthritis, a degenerative joint disease that often leads to joint replacement surgery.

The new study included just over 500 overweight and obese Americans who either had mild to moderate osteoarthritis or risk factors for the disease. The study participants were randomly assigned to a control group that lost no weight, a group that lost a little weight, or a group that lost more than 10 percent of their body weight.

Four years of follow-up showed significant weight loss protected against cartilage degeneration and that larger amounts of weight loss provided more protection, according to the study to be presented Monday at the annual meeting of the Radiological Society of North America, in Chicago.

Research presented at meetings is considered preliminary until published in a peer-reviewed journal.

"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," study author Dr. Alexandra Gersing, from the department of radiology and biomedical imaging at the University of California, San Francisco, said in a society news release.

"However, those with 5 to 10 percent weight loss had almost no difference in cartilage degeneration compared to those who didn't lose weight," she added.

Significant weight loss not only slows the loss of knee joint cartilage, it also reduces the risk of osteoarthritis. Along with moderate exercise, weight loss is one of the best ways to prevent the disease, Gersing said.

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