By Robert Preidt
But losing pounds from exercise alone will not help preserve those aging knees, the researchers found.
Obesity is a major risk factor for painful knee osteoarthritis -- degeneration of cartilage caused by wear and tear. Weight loss can slow the disease, but it wasn't clear until now if the method of weight loss made a difference.
Apparently, it does.
"These results add to the hypothesis that solely exercise as a regimen in order to lose weight in overweight and obese adults may not be as beneficial to the knee joint as weight loss regimens involving diet," said lead author Dr. Alexandra Gersing.
Gersing made her comments in a news release from the Radiological Society of North America (RSNA). She's with the University of California, San Francisco's department of radiology and biomedical imaging.
The study included 760 overweight or obese adults who had mild to moderate knee osteoarthritis or were at risk for it. The participants were divided into a "control group" of patients who lost no weight, and a group who lost weight through either a combination of diet and exercise, diet alone, or exercise alone.
After eight years, cartilage degeneration was much lower in the weight-loss group than in the control group. However, that was true only of people who lost weight through diet and exercise, or diet alone, the investigators found.
Study participants who exercised without changing their diet lost as much weight as those who slimmed down through diet plus exercise or diet alone, but there was no significant difference in cartilage degeneration compared to the control group.
The study was scheduled for presentation Tuesday at the annual meeting of the RSNA, in Chicago. Research presented at medical meetings should be considered preliminary until published in a peer-reviewed medical journal.