Association between relative fat mass and cardiometabolic multimorbidity in middle-aged and older adults and those with sarcopenia in two prospective cohorts

Obesity is a well-established risk factor for cardiometabolic diseases. While the Relative Fat Mass (RFM) index has been proposed as an alternative adiposity measure, its value for predicting cardiometabolic multimorbidity (CMM) in Chinese and American populations remains insufficiently evidenced. Sarcopenia poses a significant health burden to the aging Chinese population, but the predictive utility of RFM for CMM risk specifically in middle-aged and older adults with sarcopenia is currently unexplored. This study aimed to evaluate whether RFM is a superior predictor of CMM compared to Body Mass Index (BMI) and Waist-to-Height Ratio (WHtR), and to assess its specific predictive advantage over BMI within the Chinese sarcopenic population.