If you’re overweight and lose weight, chances are you’ll be doing your knees a world of good, says a new study published in the journal Radiology. Researchers from the University of California, San Francisco, found that overweight and obese people who lose a substantial amount of weight over four years significantly lowered degeneration of their knee cartilage.

Obesity is a risk factor for osteoarthritis, says the National Institutes of Health since extra pounds can place extra pressure on joints and cartilage, causing them to erode. In addition, extra body fat may produce higher levels of chemicals that cause inflammation in the joints, which also raises the risk for osteoarthritis.

“For this research, we analyzed the differences between groups with and without weight loss,” said the study’s lead author Dr. Alexandra Gersing. “We looked at the degeneration of all knee joint structures, such as menisci, articular cartilage, and bone marrow.”

Researchers investigated the link between weight loss and the progression of cartilage changes on MRI over a 48-month period in 640 overweight and obese patients. All had risk factors for  osteoarthritis or MRI evidence of mild to moderate osteoarthritis.

Patients were categorized into three groups: those who lost more than 10 percent of their body weight, those who lost five to 10 percent of their body weight, and a control group whose weight remained stable.

Patients who lose 5 percent of their total weight had lower rates of cartilage degeneration when compared with stable weight participants. Degeneration slowed even more in patients who lost 10 percent of their body weight.

In addition, the researchers also saw changes in the menisci. Menisci are crescent-shaped fibrocartilage pads that protect and cushion the joint.

“The most exciting finding of our research was that not only did we see slower degeneration in the articular cartilage, we saw that the menisci degenerated a lot slower in overweight and obese individuals who lost more than 5 percent of their body weight, and that the effects were strongest in overweight individuals and in individuals with substantial weight loss,” she said.

“Our study emphasizes the importance of individualized therapy strategies and lifestyle interventions in order to prevent structural knee joint degeneration as early as possible in obese and overweight patients at risk for osteoarthritis or with symptomatic osteoarthritis,” Gersing said.

According to the Centers for Disease Control and Prevention, osteoarthritis is the most common form of arthritis. In addition to obesity, risk factors include age (the risk increases with age), sex (more women have the condition), and joint injury or overuse.

Osteoarthritis affects more than 30 million American adults.