Studies have shown that losing even a small amount of weight can lower uric acid levels, and losing more weight has a bigger effect on reducing uric acid. “Losing weight drags down uric acid levels. If you get rid of the root cause, your risk will drop,” says Dr. Choi.

Fat and Psoriatic Arthritis

What It Is

Psoriatic arthritis (PsA) is a type of inflammatory arthritis that affects up to 30 percent of people with psoriasis, an autoimmune condition that causes scaly and inflamed skin. Psoriasis usually precedes psoriatic arthritis.

Why Obesity Matters

According to studies, obesity is a risk factor for psoriasis and is associated with more severe disease. People with psoriasis are more likely than people without it to have a higher BMI and higher levels of the obesity-related hormone leptin. One of the first studies to look at the link between psoriasis and the development of PsA found that psoriasis patients who are obese at age 18 had triple the risk of developing PsA than those with a normal BMI – and they developed PsA earlier in life.

“It is a double whammy; first they get psoriasis, then they get psoriatic arthritis,” says Dafna Gladman, MD, professor of medicine at the University of Toronto and co-author of many studies on psoriatic arthritis.

The exact mechanism, however, is unknown. “There are a lot of metabolic things going on [in obesity] – adiponectin, leptin, pro-inflammatory cytokines that are increased. We don’t know if it is just the fat, or if it is what the fat is associated with,” says Dr. Gladman.

What is certain is that being overweight or obese plays a role in PsA. “Because you carry around more weight, especially in the lower extremities and back, there are additional forces at play,” says Dr. Gladman. “Also, when you are overweight, it’s difficult to figure out the dose of medication you might need. [Dosing of] Remicade is weight-related, but other drugs don’t have that, so obese patients may be undertreated because we don’t know the precise dose we should be using.”

Fat and Lupus

What It Is

Systemic lupus erythematosus is a chronic, inflammatory autoimmune disease in which the body’s immune system mistakenly attacks its own tissues and organs.

Why Obesity Matters

Several studies have found that the rates of obesity are higher in people with lupus than in the general population. Obesity in patients with lupus is associated with high levels of disability and possibly cognitive impairment.

“What we found is that there is a higher rate of obesity among women with lupus than there is in general population, and there is a big effect of obesity on functioning,” says Patricia Katz, PhD, professor of medicine and health policy at the University of California, San Francisco.