Controlled data show that obesity is a risk factor for psoriasis and that psoriasis severity is correlated with the degree of overweight. No controlled interventional studies reporting on the effect of weight loss on psoriatic skin manifestations have been published and data from case reports are conflicting.

Patients with psoriasis demonstrate an increased susceptibility to atherosclerotic comorbidities such as arterial hypertension, coronary vascular disease, stroke, hyperlipidemia and type II diabetes and in severe psoriasis there is an increased risk of early death. Lately the role of inflammation in the atherosclerotic process has been highlighted and the link between psoriasis and atherosclerosis may be explained by the concomitant systemic inflammation in psoriasis. Similarly a state of low level inflammation is seen in obesity where macrophages and adipocytes begin to show overlap in function and gene expression. This leads to an increased migration of macrophages into the adipose tissue and an increased secretion of pro-inflammatory cytokines. In summary, these data and theoretical considerations suggest that weight loss in obese patients with psoriasis may improve skin manifestations and reduce the risk of atherosclerotic comorbidity.

Inclusion Criteria:

• moderate/severe psoriasis at inclusion or previous to systemic immunosuppressive therapy
• BMI > 27

Exclusion Criteria:

• pregnancy/breast feeding
• diabetes requiring insulin treatment
• severe heart/kidney/liver disease
• gout
• high potassium intake
• obesity due to medical conditions/medications
• use of medical treatment for obesity
• previous bariatric surgery
• intentional/unintentional weight loss up to 3 months prior to inclusion