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.

The short version

This randomised crossover trial with 42 adults who have rheumatoid arthritis (RA) explored whether a Mediterranean-style, anti-inflammatory diet changes body composition compared with a typical Western diet. RA is a chronic autoimmune condition that inflames the joints, and many patients lose muscle while keeping or gaining fat, a pattern called rheumatoid cachexia (defined here by fat-free mass and fat mass relative to Swiss reference values). Arthritis drugs do not reverse this, so the researchers asked whether food could. At Sahlgrenska University Hospital in Gothenburg, Sweden, outpatients with active RA ate each diet for 10 weeks, separated by a washout of about 4 months, in random order. Weekly food bags delivered to their homes provided 1,100 kcal a day on five days a week, roughly half their intake, and participants aimed to keep their weight steady. The Mediterranean-style diet included berries, walnuts, whole grains, fish three to four times a week, vegetarian meals and a probiotic fruit drink; the control diet had red meat and refined grains. Fat and lean mass were measured fasting by bioimpedance spectroscopy. Across all 42 participants the two diets did not differ in any body composition measure (all p > 0.20), and both periods saw lean mass rise and fat percentage fall. Employment status changed the picture: the 15 participants who were not working lost 1.77 kg of fat mass (p = 0.012) and 1.81 percentage points of body fat (p = 0.008) on the Mediterranean-style diet compared with the control diet, while those who worked showed no difference. Stomach discomfort was reported in 21% of diet periods, mostly during the Mediterranean-style diet. The authors suggest the diet may help address rheumatoid cachexia but note the employment finding may be chance, was not the trial's primary question, and was not powered for. Physical activity was not tracked during the trial, and measurements came from several operators using bioimpedance rather than DXA scanning. The authors call for studies on mechanisms and long-term effects.

Key findings

• In this crossover trial, 42 adults with rheumatoid arthritis (an autoimmune disease that inflames the joints) ate a Mediterranean-style, anti-inflammatory diet and a Western-style diet for 10 weeks each, with meals delivered to their homes and their weight kept steady.
• Across the whole group, body fat and lean mass did not differ between the two diets (all p > 0.20), and both periods showed lean mass rising and body-fat percentage falling.
• Among the 15 participants who were not working, fat mass fell 1.77 kg (p = 0.012) and body-fat percentage fell 1.81 points (p = 0.008) on the Mediterranean-style diet compared with the Western diet; those who worked showed no difference.
• Rheumatoid cachexia means losing muscle while keeping or gaining fat because of chronic inflammation, and drugs for arthritis do not reverse it.
• Body composition was a secondary outcome and the employment result may be chance, so the authors call for further studies.

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