Adults might be able to reduce their risk of arthritis by controlling their weight, a government study found.
Men who are overweight or underweight are more likely to suffer from the joint disease than adults of normal weight, the Centers for Disease Control and Prevention reported Thursday. Obese women are also at risk, but underweight women apparently aren't.Researchers don't know exactly why weight plays a role.
"The question is, did the arthritis come before the weight gain and cause it, or did it come after the weight gain as a result of it?" said Dr. Chad Helmick, a CDC epidemiologist. "Either way, avoiding excess weight is the message."
The study found that adults of both sexes who were overweight but not obese were 30 percent more likely than adults of normal weight to have arthritis. Obese men were 70 percent more likely to suffer from the disease while obese women were 50 percent more vulnerable.
The study also found that underweight men were 40 percent more likely to suffer from arthritis than men of normal weight. "We were a bit puzzled as to what that means," Helmick said.
Researchers have known that the incidence of arthritis, an often painful inflammation of the joints, increases with age, but the study's findings show that weight alone is a risk factor regardless of age.
One expert who has studied osteoarthritis of the knee said shedding extra pounds can relieve joint inflammation.
"Losing weight will make your arthritis better," Dr. David Felson, a professor of medicine at Boston University. "It's not been well studied, but it's certainly true, especially if you have knee arthritis."
The figures, taken from the National Health Interview Survey conducted from 1989 to 1991, are based on patients' own reports of arthritis.
Arthritis and other rheumatic disorders are the leading causes of disabilities in the United States, especially among women.
The disease afflicts about 40 million Americans and the number will probably grow to 60 million by 2020, the CDC said.