And people with RA – including those who have a body mass index (BMI) in the normal range – have yet another reason to watch their diet and exercise. “The disease process changes body composition in an unfavorable way; it favors having more fat and less muscle,” says Dr. Giles, who has conducted many studies on the effects of body composition and inflammatory arthritis.

In addition, researchers have found the excess fat is often located around the abdomen (known as visceral fat), which is a risk factor for heart disease and insulin resistance.

“RA patients have a 50 percent higher cardiovascular mortality risk than the general population, so controlling cardiovascular risk factors is a priority in RA patients. You don’t want to have fat that increases your risk of heart disease,” says Dr. Giles.

Fat and Gout

What It Is

Gout is a form of inflammatory arthritis that occurs when an excess of uric acid in the body leads to the formation of uric acid crystals in the joints, triggering painful attacks. These are most common in the big toe, but also occur elsewhere.

Why Obesity Matters

Obesity is closely linked to gout; as the country’s obesity rate has gone up, so has its rate of gout. According to studies, about 70 percent of people with gout are overweight and 14 percent are obese. Being obese puts a person at a higher risk of developing gout in the first place – and of getting gout 11 years earlier on average than someone of normal weight.

“In the highest [weight] group versus the lowest group, it could be a tenfold or higher risk of developing gout,” says gout expert Hyon Choi, MD, a professor of medicine at Boston University School of Medicine. Dr. Choi has authored pivotal population-based studies examining the link between gout and obesity.

So what is going on? Uric acid is formed when the body breaks down purines – a compound found in human tissue and in most foods, and concentrated in certain meats, seafood and beer. Some people’s bodies produce too much uric acid; other people’s kidneys can’t eliminate it quickly enough.

It’s worse for obese people. “When people are obese, their kidneys can’t excrete efficiently. The prime suspect is insulin,” Dr. Choi says. “When people are big, [their insulin] doesn’t work as well, so they produce more. Insulin inhibits uric acid excretion in the kidneys.”

The good news is that small changes can make a big difference. “Lifestyle matters a lot in gout, like it does for diabetes, so you can control gout if you really stick to good lifestyle [choices]. You can prevent it to large degree. You have a lot more control than in RA,” he says.