Rheumatologists often stress the importance of weight loss to their patients – extra weight contributes to joint damage, not just discomfort, and it reduces function. But this new research adds more evidence to the importance of weight loss for the entire population.

“Now we have another compelling reason to stress the importance of weight control: being overweight increases your risk for getting RA, just as being overweight increases your risk for other diseases, like heart disease, hypertension and diabetes,” says Dr. Matteson. “It’s yet another reason to really try to keep your weight ideal throughout your lifetime.”

As for why obesity appears to increase the risk of developing RA, Dr. Matteson’s team didn’t specifically study causes, but he believes there could be a variety of explanations.

“There are several biological reasons. One is that fat cells actually produce inflammatory proteins,” Dr. Matteson says. “Another is that we know people who are overweight have lower vitamin D levels generally, and that has been associated with RA.”

Scott Kahan, MD, director of the National Center for Weight and Wellness in Washington, D.C., says one downside of this study – which the researchers acknowledge in their paper – is that the study population from Olmsted County is 90 percent white, which makes it difficult to know if these findings apply to other ethnicities. But he says most scientific research has limitations and these findings are interesting.

“With this study it gives a little more data than what we’ve had in the past,” Dr. Kahan explains. He also says it adds to the big picture of the importance of being a healthy weight.

“The bottom line is that we have a whole lot of reasons why excessive weight can be destructive to our health,” Dr. Kahan says. “Ultimately we need to continue to figure out how on a personal level we can address our weight and health over time. And we have to figure out on a policy level how we can continue to support people’s healthy decision-making.”

To people who are obese and have already developed RA, Dr. Matteson has this message: “It’s not too late at all [to lose weight]. There’s some evidence that drugs that we use to treat RA don’t work quite as well in people who are overweight,” he explains, adding that you will most likely experience a variety of benefits by getting down to a more ideal weight. “The other reason it’s not too late is because when you lose that weight you are doing your joints a big favor. Your joints will thank you; they will last you longer.”