Does Weight Loss Reduce the Severity and Incidence of Psoriasis or Psoriatic Arthritis?

A Critically Appraised Topic

S.K. Mahil; S.M. McSweeney; E. Kloczko; B. McGowan; J.N. Barker; C.H. Smith


The British Journal of Dermatology. 2019;181(5):946-953. 

In This Article


Psoriasis is a chronic inflammatory skin condition characterized by scaly erythematous plaques. It currently affects 2–4% of Western populations and has a rising incidence.[1] It is associated with multisystem comorbidities, including PsA (affecting up to 30% of patients with psoriasis), obesity, metabolic syndrome and cardiovascular disease.[2,3] Psoriasis also significantly reduces patients' quality of life through psychological distress and social exclusion.[3]

Obesity, defined as BMI > 30 kg m−2, is a state of excessive fat accumulation that presents a rising public health challenge and is strongly associated with both psoriasis and PsA.[4] Obesity is more prevalent among individuals with psoriasis or PsA (30–40%) than in the general population (15–20%),[5–8] and the risk of obesity is higher in patients with severe psoriasis [odds ratio (OR) 2·23] compared with those with mild phenotypes (OR 1·46).[6] Longitudinal population-based studies suggest a causal role for obesity in psoriasis and PsA onset (adjusted risk ratios 1·87 and 3·12, respectively), and that obesity drives greater disease severity and reduces the probability of successful treatment with biologic agents by up to 50%.[9–15] This link between obesity and psoriatic conditions may be attributed, in part, to the active secretion by adipose tissue of proinflammatory cytokines that enhance T helper 17/interleukin-23-mediated inflammation, which is central to the pathogenesis of psoriasis and PsA, and an accelerated clearance of biologic agents associated with high body weight.[16]

To explore the resulting notion that weight loss may ameliorate the onset and severity of psoriasis and PsA in obese individuals, we conducted a critically appraised topic to allow physicians to counsel their patients effectively.[17]