Body fat and rheumatoid arthritis: Do men and women differ?

This study investigated whether rheumatoid arthritis patients have higher body fat and if this is more common in men than women.

Previous research has suggested that patients with rheumatoid arthritis have abnormal body composition. Patients, especially men, are more likely to have excess body fat and lean body mass deficits. Lean body mass is a measure of body composition. It is calculated by subtracting the weight of body fat from the total body weight. Therefore, the lower the value the higher the fat content.

Abnormal body composition is clinically important as excess fat (obesity) has been linked to greater disability and worse long-term outcomes for rheumatoid arthritis patients. 

This study included 190 adults with rheumatoid arthritis. Two measures of body composition were obtained: total lean body mass and a lean body mass value for the arms and legs (appendicular lean body mass; ALM). The values were then adjusted for patient height.

Men with rheumatoid arthritis had significantly lower lean body mass levels compared to the general population (who are at the 50^th percentile). On average male patient lean body mass was between the 10^th and 23^rd percentile and ALM was between the 11^th and 20^th percentile.

Men also had significantly lower lean body mass levels than female patients in this study. On average female lean body mass was between the 37^th and 47^th percentile and ALM was between the 44^th and 47^th percentile.

Male patients had higher odds of developing skeletal muscle loss (sarcopenia). Sarcopenia is linked to increased falls, bone fractures and disability for patients.

The authors concluded that rheumatoid arthritis is linked to lean body mass deficits. Larger deficits were seen in men.