"Obesity is a huge issue for patients with psoriasis," said Dr. Joel Gelfand, an associate professor of dermatology and medical director of the clinical studies unit at the Hospital of the University of Pennsylvania, in Philadelphia. "If you're obese with psoriasis, psoriasis is less likely to get clear."
There are a couple reasons excess weight can exacerbate a person's psoriasis. First, psoriasis is an inflammatory disease, and obesity is a known cause of inflammation, said Dr. Larry Green, chairman of the research committee for the National Psoriasis Foundation.
"Anytime someone is obese, it's going to affect how their body can heal because it's a stress on the body and stress affects inflammation," Green said. "By losing weight, they're going to reduce the burden on their body."
Another possibility is that obesity may cause immune system responses that are very similar to those prompted by psoriasis.
"Obesity is associated with the same elevations of cytokines in the blood that promote psoriasis," Gelfand said. Cytokines are small signaling proteins used to regulate the body's immune response.
On a more mundane level, obesity also causes skin friction as parts of the body rub against each other, another expert said.
"If skin rubs against skin, psoriasis gets worse," said Dr. Jeffrey Weinberg, a dermatologist at Beth Israel Medical Center in New York City. "Friction makes psoriasis get worse."
Gelfand said it's difficult to draw major clinical conclusions from such a small pilot study, adding that the people in the Danish study suffered from mild to moderate psoriasis and therefore were less likely to experience a vast improvement in their symptoms from weight loss.
"Larger studies in a population of patients with more severe skin disease are necessary to determine if these findings are clinically important," he said.
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