Impact of weight‐loss interventions on psoriasis severity: A systematic review and meta‐analysis

Background: Psoriasis affects at least 60 million people worldwide, and 80% also live with overweight or obesity. Excess weight increases susceptibility to psoriasis and is associated with more severe disease. Objective: To evaluate the impact of weight‐loss interventions on psoriasis severity (Psoriasis Area and Severity Index [PASI], PASI50, PASI75, PASI100 [50%/75%/100% reduction in baseline PASI, respectively]) and quality of life (Dermatology Life Quality Index [DLQI]). Methods: We systematically searched five databases and two trial registries (inception to 03/09/2025). Outcomes were informed by patient focus‐group discussions. Randomized controlled trials (RCTs) in adults with psoriasis, comparing any weight‐loss intervention versus usual care or a lower‐intensity weight‐loss intervention, were included. Studies had to report a change in weight and ≥1 psoriasis severity or quality‐of‐life measure. Random effects meta‐analyses were used. Results: Thirteen RCTs (1145 participants) with 14 comparisons were included. Eleven interventions advised dietary changes, of which four included physical activity. Three used weight‐loss medications. Across 14 comparisons (n = 1145, mean difference (MD) in weight change: −6.7 kg), weight‐loss interventions produced a greater reduction in PASI versus control: MD −2.5 (95%CI: −3.8 to −1.1, I2 = 85.2%). We found a significant effect of weight‐loss interventions on the likelihood of achieving PASI75 (RR = 1.6, 95%CI: 1.1–2.2, I2 = 22.6% [based on six comparisons, n = 681, MD in weight change: −7.3 kg]). There was no statistically significant effect of the interventions on the likelihood of achieving PASI50 (RR = 1.5, 95%CI: 0.9–2.4, I2 = 72.8% [based on four comparisons, n = 509, MD in weight change: −4.0 kg]) or PASI100 (RR = 1.6, 95%CI: 0.3–9.7, I2 = 0.0% [based on two comparisons, n = 334, MD in weight change: −5.2 kg]), but both analyses were limited by few studies. Across seven comparisons (n = 364; MD in weight change −7.8 kg), weight‐loss interventions were associated with a significant improvement in DLQI compared to control: MD −5.0 (95%CI: −9.7 to −0.3, I2 = 96.0%). Conclusion: High‐certainty evidence suggests weight‐loss interventions can improve psoriasis severity and quality of life, and should be considered as part of routine treatment.