For years there has been anecdotal evidence from physicians who see a link between overweight and psoriasis, and indeed, several studies have shown a connection. But until recently (Arch Intern Med 2007;167(15):1670-5) there haven't been any long-term prospective (following subjects over time) studies to assess this connection.
This research made use of data collected as part of the Nurses' Health Study II, a long-term, large scale study of over 116,000 nurses who were between 25 and 42 years of age in 1989, the study's inception. After the initial questionnaire, which included data about height, weight, smoking and alcohol status, eating habits, and medical conditions (including psoriasis), similar questionnaires were administered every two years.
The researchers at Harvard Medical School, Brigham and Women's Hospital, and the University of British Columbia, Vancouver compared those women who reported a diagnosis of psoriasis with those who did not have that condition. They found a remarkable rising risk of developing psoriasis correlating with a higher Body Mass Index: those women who were simply in the overweight category (between 25 and 29.9) increased their risk of psoriasis by 40%! Obese women (with a BMI over 30) saw their risk increase by nearly 50%, while very obese women (BMI over 35) were at an incredibly increased risk of 169% (that's not a typo).
Dr. Setty's team also correlated weight change since the age of 18 with the risk of psoriasis, and found that those women who were obese (BMI of 30 or greater) at the age of 18 were 73% more likely to develop psoriasis.
What this means for you
Psoriasis is a chronic inflammatory disease, and obesity has been shown to cause a chronic, low-grade, inflammatory state in the body. Although there have been case reports of complete remission of psoriasis symptoms in those who lose significant amounts of weight, why work for remission when maintaining a normal weight will help you avoid psoriasis completely?