Women who were overweight or obese had a significantly increased risk for rheumatoid arthritis. (Shutterstock photo)

Maintaining a healthy weight is important for many health reasons, including preventing rheumatoid arthritis (RA). According to a new study presented at the 2012 annual meeting of the American College of Rheumatology, women who are overweight or obese have an 18 to 19 percent increased risk of developing rheumatoid arthritis.

“Controlling your weight not only prevents diabetes and cardiovascular diseases, but it can also prevent RA,” study researcher Bing Lu, MD, assistant professor of medicine at Brigham and Women’s Hospital in Boston, told Arthritis Today. “Previous studies have had inconsistent results, but we were able to confirm that obesity increases RA risk based on two large studies, with a much better study design and a very large sample size.”

Rheumatoid arthritis and obesity study

For the research, reported by Arthritis Today, Lu’s team pulled data from two previous studies, the Nurses’ Health Study (NHS), and the Nurses’ Health Study II (NHSII). Collectively, more than 200,000 nurses in the studies were evaluated, and body mass index (BMI) was calculated.

Women with a BMI of 25.0 to 29.9 were classified as overweight, and women with a BMI over 30.0 were classified as obese.

Rheumatoid arthritis has been linked to obesity in previous studies. (Shutterstock photo)

In the final results, both the overweight group and the obese group demonstrated an 18 to 19 percent increased risk for rheumatoid arthritis when compared to the women in the normal weight group.

Despite the findings, researchers caution the data only indicates a link, not a cause-effect relationship between weight and rheumatoid arthritis.

“The study only shows an association,” said Allen Anandarajah, MD, clinical director and associate professor of medicine in the division of allergy, immunology and rheumatology at the University of Rochester, in New York, to Arthritis Today. “It could be argued that they gained weight due to decreased mobility or function as a result of RA, or even possibly secondary to some of the treatments for RA, like steroids.”

Despite the evidence, other experts feel weight gain is a contributing factor when it comes to rheumatoid arthritis, rather than a consequence of the disease. Eric Matteson, MD, the chair of rheumatology at the Mayo Clinic in Rochester, Minnesota, previously published supporting research linking obesity to rheumatoid arthritis.

“We know that fat cells produce inflammatory proteins,” he said. “So there’s probably a connection between having an excess amount of fat cells and turning on the autoimmune cells in the body.”

Weight control is, in general, an important part of staying healthy and preventing chronic diseases.

“We can add rheumatoid arthritis to the very long list of health problems that are associated with obesity,” said Dr. Matteson. “What’s important in primary care is that physicians continue working with patients to help them maintain a normal weight, stay fit and exercise.”