Study: Belly Fat More Predictive of Psoriasis Than Overall Body Fat

Key Takeaways

• Central adiposity, particularly waist-to-hip ratio, is more strongly associated with psoriasis risk than overall body fat.

• Researchers for this study report the association is more pronounced in females and persists regardless of genetic predisposition.

• The authors said clinical approaches to psoriasis risk management should include abdominal fat and weight-related interventions.

Central adiposity—particularly abdominal fat—is more strongly linked to psoriasis risk than overall body fat, according to a new analysis published in the Journal of Investigative Dermatology.

Study investigators analyzed data from more than 330,000 individuals of White British ancestry in the UK Biobank, including over 9,000 with psoriasis, resulting in one of the most detailed examinations to date of the impact of fat distribution on psoriasis susceptibility. The researchers looked specifically at 25 adiposity measures. Some, such as central fat indicators like waist-to-hip ratio (OR = 1.26, P = 8.74e-65), abdominal fat ratio, and visceral adipose tissue volume—showed the strongest associations with psoriasis risk.

“Where fat is stored in the body matters when it comes to psoriasis risk,” said lead author Ravi Ramessur, MD, of St John’s Institute of Dermatology, King’s College London, in a news release about the study. “Central fat—especially around the waist—seems to play a key role. This has important implications for how we identify individuals who may be more likely to develop psoriasis or experience more severe disease, and how we approach prevention and treatment strategies”.

Notably, the relationship between abdominal fat and psoriasis was particularly pronounced in women. Visceral fat volume had a significantly higher odds ratio in females (OR = 1.35) compared to males (OR = 1.13), and interactions with sex reached statistical significance (P = .0067).

To further investigate whether genetic predisposition modifies the fat-psoriasis link, the researchers examined polygenic risk scores (PRS) for psoriasis, including and excluding HLA-C06:02, the major susceptibility allele. A significant interaction was found between waist-to-hip ratio and the full psoriasis PRS (β = –0.019, P = .047), but the effect disappeared when HLA-C06:02 was excluded. Waist-to-hip ratio was also more strongly associated with psoriasis in HLA-C*06:02–negative individuals.

“These findings suggest that abdominal fat may represent an independent and modifiable risk factor for psoriasis, regardless of genetic susceptibility,” said senior author Catherine H. Smith, MD, also of King’s College London. “This reinforces the importance of measuring waist circumference and promoting healthy weight strategies in psoriasis care”.

Although the study provides new insights, limitations include the reliance on self-reported or administrative records for psoriasis diagnosis, and the homogeneity of the cohort (White British participants), which may limit generalizability. The authors advocate for further studies involving more diverse populations and dermatologist-confirmed cases.

“Our findings suggest that central body fat contributes to psoriasis risk irrespective of genetic predisposition and reinforce the importance of measuring waist circumference and pro-active healthy weight strategies in psoriasis care,” the authors concluded.