Improvements in Body Composition after a Proposed Anti-Inflammatory Diet Are Modified by Employment Status in Weight-Stable Patients with Rheumatoid Arthritis,a Randomized Controlled Crossover Trial

Rheumatoid Arthritis (RA) is an autoimmune disease affecting peripheral joints. Chronic activation of inflammatory pathways results in decreased function and the development of comorbidities, such as loss of lean mass while retaining total body mass. The objective of this report was to assess whether dietary manipulation affects body composition in patients with RA as a secondary outcome. Fifty patients were included in a randomized controlled crossover trial testing a proposed anti-inflammatory Mediterranean-style diet compared to a Western diet. Body composition was measured by bioelectrical impedance spectroscopy in patients without implants (n = 45). Regardless of treatment, fat-free mass increased and fat mass percentage decreased during weight stability, but no differences between intervention and control in the whole group (n = 42, all p > 0.20) were found. Interaction analysis revealed that participants who were non-employed (n = 15) significantly decreased in fat mass (−1.767 kg; 95% CI: −3.060, −0.475, p = 0.012) and fat mass percentage (−1.805%; 95% CI: −3.024, −0.586, p = 0.008) from the intervention compared to the control period. A Mediterranean-style diet improved body composition in non-employed participants (n = 15). The group as a whole improved regardless of dietary allocation, indicating a potential to treat rheumatoid cachexia by dietary manipulation.