Dietary Interventions, Resulting Weight Loss Improve Symptoms of Psoriatic Arthritis

Preliminary data resulting from dietary interventions in patients with psoriatic arthritis (PsA) and obesity indicate that weight loss of ≥5% body weight may lead to improvements in disease activity.1

These findings resulted from an analysis led in part by Stefan Siebert, MD, PhD, from the School of Infection and Immunity at the University of Glasgow in the United Kingdom. Siebert and colleagues highlighted relevant research associated with the topic, including data suggesting that those with PsA and psoriatic disease in general are more likely to have obesity than those within the general population.2

“In this narrative review, we highlight the mounting evidence for the adverse, and likely pathogenic, role of obesity in PsA and outline what options may be available for rheumatologists to address this currently unmet need,” Siebert and colleagues wrote.1 “We also highlight key unanswered questions that urgently require attention to provide the robust evidence needed to tackle obesity in PsA.”

The investigators discussed extensive research that had evaluated any relationship between PsA and obesity among patients. The data they highlighted at first in this analysis emphasized that PsA maintained a link to increased rates of obesity along with cardiometabolic comorbidities.

Those who live with psoriasis and PsA were noted by Siebert and colleagues as significantly more likely to be obese as opposed to those included in the general population. Studies they highlight reporting that between 27% - 40% of individuals with psoriatic disease are shown to have a body mass index (BMI) of 30 kg/m² or greater.

The team highlighted similar to trends in other chronic inflammatory diseases, noting that those who live with PsA tend to have a higher prevalence of cardiometabolic conditions. Notably, such cardiometabolic comorbidities are already common in early-stage PsA. The investigators suggest that this may indicate that they are not merely the result of longer-term periods of inflammation. Prevalence observed in metabolic syndrome was noted by the team as greater in PsA than in psoriasis or rheumatoid arthritis, according to data they highlight.

Central obesity, determined by waist circumference, was also found in prior analyses as correlating with increased likelihood of psoriatic diseases. Such findings were also consistent with data indicating that those who live with PsA exhibit greater amounts of unhealthy visceral fat as well as ectopic fat deposits. These deposits then lead to a body fat distribution pattern which the investigators noted is comparable to that observed in those with type 2 diabetes.

The investigative team noted that, in 1 significant finding, obesity was suggested to be unlikely to be simply a result of decreased physical activity caused by joint pain or by fatigue. They pointed to growing epidemiological and genetic data indicating that obesity not only precedes but may actively contribute to the development of PsA as well as psoriasis.

One such study was the prospective Nurses’ Health Study II, the conclusions of which pointed to a dose-dependent relationship between BMI increases among patients and the risk of developing psoriasis across different age cohorts.

An additional analysis revealed that those who have a BMI of ≥30 kg/m² were 3 times more likely, and those with a BMI greater than 35 kg/m² were over 6 times more likely, to see PsA develop versus individuals showing a BMI that was under 25 kg/m². Such findings also reinforce obesity’s role as a key risk factor in the progression of psoriatic disease.

Genetic research employing Mendelian randomization also supports a causal connection between obesity and the development of psoriatic diseases such as PsA. Through the use of single-nucleotide polymorphisms (SNPs) linked to BMI, investigators in this study found that each 1 kg/m² increase in genetically predicted BMI showed a link with a 9% higher odds of psoriatic disease development.

Conversely, the investigative team pointed to a lack of association between genetic predisposition to psoriasis and an increased BMI. In an additional Mendelian randomization study, investigators had demonstrated in their findings that genetically predicted higher BMI was linked to PsA risk increases (odds ratio [OR] 1.38 per 4.8 kg/m² increase). In contrast, the data suggested that genetic risk for PsA did not correlate with increased BMI.

“In conclusion, there are now genuine opportunities to tackle the significant unmet and progressively increasing need associated with obesity in PsA not addressed by current immunomodulatory therapies,” they wrote.1 “The key now is to prove when and in which patient groups these therapies are clinically and cost effective, and then to optimally implement them into the clinic to provide more holistic care and improved outcomes for our patients.”

References

1. Siebert S, Sattar N, Ferguson LD, Weighing in on Obesity and Psoriatic Arthritis – Time to move beyond association to robust randomised trials, Joint Bone Spine (2025), doi: https://doi.org/10.1016/j.jbspin.2025.105904.

2. Vallejo-Yagüe E, Burkard T, Möller B, et al. Comparison of Psoriatic Arthritis and Rheumatoid Arthritis Patients across Body Mass Index Categories in Switzerland. J Clin Med 2021;10:3194. https://doi.org/10.3390/jcm10143194.