Ringing in the New Year with a resolution to lose weight? Recent research into the relationship between weight and psoriasis may give you extra encouragement.
According to a study conducted by a research team in Denmark, losing weight may lead to a reduction in psoriasis severity in patients who are overweight. On top of that, skin improvement might stick around even after the diet is over.
Tipping the scales of psoriasis
The study put overweight psoriasis patients on a strict diet, and then followed them for about a year after the diet ended.
For the first part of the study, 60 overweight people with psoriasis were divided into two groups. Half of them were put on a low-calorie diet for four months. At first, participants ate only 800-1,000 calories a day. After about two months of that, they spent another two months eating about 1,200 calories a day.
“The first eight weeks is not very much fun. It really takes a lot of discipline,” said Dr. Peter Jensen, a dermatologist at Copenhagen University Hospital and the lead author of the study.
(He should know—he actually tried the diet himself to better understand what his patients were going through.)
The hard work paid off. According to the results of the study, published in May 2013 in the journal JAMA Dermatology, the patients on the diet lost about 15 kilograms—or roughly 30 pounds—more than the patients who weren’t on the diet.
Weight loss happened quickly and helped keep patients committed to the diet, Jensen said.
“In the beginning, patients are wondering, ‘Will this work for me?’ But they can tell straightaway, and see in the mirror straightaway, which is really good. That encourages them to go on.”
Another thing patients noticed in the mirror was an improvement in their skin. As reported in the study, patients on the diet saw a reduction in their psoriasis severity. Although the reduction did not reach statistical significance, according to Jensen, the improvement was noticeable to patients. The majority of patients, he said, reported that they looked and felt better even before Jensen or the other researchers had a chance to measure that improvement.
“They were telling me before we even got to that, ‘I’m better, and I’m so happy. I look a lot better than I did before,’” he said.
What happens when the diet stops?
For the second part of the study, Jensen and his colleagues investigated whether patients kept seeing clearer skin even after the diet stopped. This time, the patients who were in the control group during the initial study were invited to do the same low-calorie diet. For a year afterward, patients met with a nutritionist about once a month but weren’t on a formal weight loss intervention, Jensen said.
About half the patients dropped out of the study. Those who didn’t regained about 5 kilograms, or 11 pounds, Jensen said. But, as he reported at the European Academy of Dermatology and Venereology meeting in October, they still maintained their skin improvement.
The fat-inflammation connection
Jensen and his colleagues first got the idea to study the effect of weight loss on psoriasis severity after seeing the results of other studies indicating that obesity increased the risk for psoriasis.
“We thought, what happens if we turn the tables around? What happens if you lose weight?”
The connection between weight loss and psoriasis severity might be explained by the relationship between body fat and inflammation, Jensen said.
Inflammation in psoriasis is driven by pro-inflammatory proteins, known as cytokines. Cytokines play a key role in the immune system’s inflammatory response. These cytokines also lead to the inflammatory reaction seen in autoimmune diseases like psoriasis and psoriatic arthritis.
Cytokines can also be, as Jensen explained, secreted by fat, which goes by the technical term adipose tissue.
“One hypothesis in the literature is that as you become more obese or overweight, the adipose tissue secretes inflammatory cytokines. These cytokines are also key cytokines in psoriasis pathogenesis. So the obesity kind of fuels the psoriasis,” he said.
Jensen thinks there is a possibility that in overweight patients with more severe psoriasis, weight loss could bring about an even greater reduction in inflammation—and a bigger improvement in psoriasis.
What about treatment?
Jensen and his colleagues did not directly analyze the impact of treatment. Patients enrolled in the study could be on any treatment, but they had to be on the same treatment for at least three months, he said.
Other researchers are looking at the connection between weight and psoriatic disease, and how treatment fits into the picture. A March 2014 study in the British Journal of Dermatology found that diet and exercise, combined with treatment, could reduce psoriasis severity in overweight patients. Another study, published in June 2014 in Annals of the Rheumatic Diseases, found that weight loss and treatment may work together to improve psoriatic arthritis in overweight patients.
One more reason to stay healthy
Jensen hopes to conduct another weight-management study in the future. In the meantime, he said, he tells his patients who are overweight that there is evidence suggesting that losing weight may improve their psoriasis.
“I will say to them also that evidence is clear that if you gain more weight, there is risk that your psoriasis becomes worse.”
In addition, he said, he reminds patients that people with psoriasis have increased risk for issues like cardiovascular disease, another reason to stay on top of their weight. Heart disease, diabetes and metabolic syndrome are some of the comorbidities, or related conditions, associated with psoriatic disease.
“I always emphasize that it’s important for us all to live a healthy lifestyle, but it’s even more important for patients with psoriasis because of their increased cardiovascular risk,” he said.
Editor’s note: The National Psoriasis Foundation does not endorse this or other dietary interventions for the treatment of psoriatic disease. Always consult with your doctor to determine the best dietary plan for living with psoriatic disease.
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