Being overweight or obese is associated with a reduced risk that men, but not women, will develop rheumatoid arthritis (RA), according to Rheumatology.

Researchers examined the risk that people who were overweight or obese (body mass index [BMI] > 25kg/m2) when they enrolled into one of two health surveys (30,447 and 33,346 participants) would develop RA compared to those with a healthy BMI (18.5-25kg/m2). Across the two surveys, 187 men and 275 women developed RA. Current smoking approximately doubled rheumatoid arthritis risk (odds ratios: 3.35 and 1.97 in men; 1.68 and 1.61 in women).

After adjusting for smoking and other confounders, overweight or obese men were 63 and 26 per cent less likely to develop RA in the two studies. Weight did not seem to influence RA risk in women. The authors speculate that “metabolic pathways related to adipose tissue and hormonerelated factors” might account for the findings.

^{(doi:10.1093/ rheumatology/kev313)}