Don’t Scratch that Itch, Starve it

Psoriasis patients may see less symptoms and a better quality of life if they lose weight

(RxWiki News) Psoriasis is a disease of the skin. But for patients with psoriasis, the condition is much more than that. The unsightly patches can be embarrassing and affect day-to-day life.

Some studies have shown a link between obesity and psoriasis. So it is natural to wonder whether weight loss improves skin symptoms such as itching and scaling, helping patients live relatively better lives. 

A recent study suggests that psoriasis patients can benefit from losing weight with a low-calorie diet.


Ask your doctor for help finding a nutritionist.


The study was conducted by Peter Jensen, MD, PhD, of the Department of Dermato-Allergology at Copenhagen University Hospital Gentofte, Hellerup, Denmark, and collaborators from the university and other institutions in Denmark.

The objective of the study was to examine the relationship between weight loss and severity of psoriasis in overweight patients.

The researchers conducted a 16-week study with 60 participants who were all overweight and had psoriasis. Half of the participants, chosen randomly, were part of the study group and were given a low calorie diet. This diet consisted of 800 to 1,000 calories per day for the first eight weeks and 1,200 calories per day for the next eight weeks.

The remaining participants were part of a control group and were asked to eat regular healthy foods. The researchers ensured that all participants met daily nutrient intake requirements.

The participants were evaluated for psoriasis symptoms and quality of life changes.

Psoriasis symptoms were measured using Psoriasis Area and Severity Index (PASI), which is calculated using the size of the psoriasis patches and severity as indicated by redness, thickness and scales. The PASI was measured at different points in the study.

The measure of quality of life used was the Dermatology Life Quality Index (DLQI). DLQI is calculated by having participants answer questions such as how much their condition affects their daily activities and how much uneasiness it causes.  

At the end of 16 weeks, the patients on a low calorie diet lost significantly more weight than the control group on a routine diet.

The average PASI score at the beginning of the study for both groups was 5.4. PASI scores can range from 0 to 72 with higher scores indicating higher severity. 

After 16 weeks, the patients on the low calorie diet saw a fall in PASI scores of around 2 points, indicating an improvement in their condition. The PASI scores fell by 0.3 points in the group on a regular diet.

Both the drop in PASI score and weight loss were more pronounced in the first eight weeks and then leveled out in the next eight weeks when calorie consumption was slightly increased.

The DLQI fell by 2.7 points in the low calorie diet group compared to 0.7 points in the control group. The questionnaire results indicated that the patients in the low calorie diet group reported fewer issues related to psoriasis and a better quality of life.

The authors noted several limitations to their study, including the short length of the study and the possibility that the stringent diet and the weight loss may not be sustainable.

In addition, the investigator who calculated the PASI scores knew which group each participant belonged to. This could have led to bias in calculating the scores since the PASI scores are based on observation of the psoriasis patches by a researcher.

One big limitation of the study was that the decline in PASI scores was not very significant for the low calorie diet group, suggesting that the change could have been a coincidence.

Longer studies with less bias and more statistically significant results are needed to confirm this study's findings and examine the reasons why weight loss leads to improvement in psoriasis.

“At present, the role of weight loss as a treatment for psoriasis in obese patients is unclear, but it is reasonable to assume that weight loss in such patients may reduce the obesity-induced inflammation, which may in turn improve the skin disease,” the authors wrote.

This study was published in May in JAMA Dermatology

The research was funded by Cambridge Manufacturing Company Ltd, the Michaelsen Foundation, the Aase and Ejnar Danielsen Foundation, the Research Foundation of the Danish Academy of Dermatology, the Danish Agriculture and Food Council, the Jacob Madsen and Olga Madsen Foundation, the Danish Psoriasis Research Foundation and the Medical Research Foundation of the Capital Region of Denmark.

The authors did not disclose any conflicts of interest and noted that the sponsors had no role in the design or conduct of the study.

Review Date: 
May 31, 2013