LAUSR

Background Obesity is a disease characterized by much fat accumulation and abnormal distribution, which was related to cardiovascular diseases, diabetes mellitus (DM) and muscular skeletal diseases. The aim of this study was to evaluate the usefulness of appendicular skeletal muscle mass to total body fat ratio (ASM/TBF) in screening for the risk of obesity in elderly people. Methods A prospective study was carried out with 446 participants (non-obese elderly people with body mass index (BMI) < 28 kg/m 2 ) who underwent baseline and an average around 2.2-year follow-up health check-up examinations. Results The mean age at baseline was 63.6 years. The incidence of new obesity was 5.4% during follow-up. Linear regression demonstrated that baseline ASM/TBFs were negatively correlated with follow-up BMIs in both men and women ( β  = − 1.147 (− 1.463—-0.831) for men and − 4.727 (− 5.761—-3.692) for women). The cut-off points of baseline ASM/TBF in elderly people for obesity were 1.24 in men and 0.90 in women which were identified by Classification and Regression Tree (CART). Logistic regression showed that both men and women with decreased ASM/TBF had higher risks of obesity over the follow-up period ( Relative Risk ( RRs ) = 5.664 (1.879–17.074) for men and 34.856 (3.930–309.153) for women). Conclusions Elderly people with a low ASM/TBF had a higher risk of new obesity, which suggested that ASM/TBF should be considered in obesity management in the elderly.