Background: The Asian phenotype of central obesity is intriguing. Current data suggest links between central obesity and cardiovascular (CV) risks. However, age-related sarcopenia (resulting in loss of skeletal muscle) may falsely reduce body mass index (BMI), leading to inaccurate measures of obesity. We aim to determine how waist circumference (WC), would compare against BMI, in differentiating obesity, among older adults. Further, we explore the differential association between each obesity definition and myocardial ageing. Methods: We performed anthropometric and CV examinations on a cohort of asymptomatic aged adults. Myocardial ageing was defined by ratio of peak velocity flow in early diastole E (m/s) to peak velocity flow in late diastole by atrial contraction A (m/s). For BMI, a cut-off of 27.5kg/m 2 was used, and WC cut-offs of >90cm for males and >80cm for females. Results: Among n=970 adults (mean age 73±4 years, 432 (44%) males), 124 (12.8%) were obese by BMI definition while 347 (35.7%) were obese by WC definition. Inter-definitional agreement was fair between BMI and WC (cohen’s κ=0.345). More women (66% vs 50%, p<0.001) and older participants (63±14 vs 65±11 years, p=0.007) were defined as obese by WC definition, while age and gender did not differentiate obese versus non-obese as defined by BMI. There were more hypertension (p<0.001) and diabetes mellitus (p<0.001) among the obese as defined by both definitions, compared to non-obese. Based on either definition, obese participants had significantly lower E/A ratio [(1.13 ± 0.46 vs 0.98 ± 0.35; P < 0.001 using BMI), (1.17 ± 0.49 vs 1.00 ± 0.37; P < 0.001 using WC)] compared to non-obese. Left atrial volume index was larger in obese in both the BMI group (20.5 ± 7.43 vs 22.3 ± 7.90; P = 0.020) and WC group (20.0 ± 6.9 vs 22.1 ± 8.3; P < 0.001). By multivariate regression, WC, but not BMI, was independently associated with E/A (β=-0.114, SE -0.114±0.024, p<0.001). Conclusion: Obesity prevalence varies depending on the definition used. Among Asians, waist circumference identifies higher prevalence of obesity, possibly related to central adiposity. While impact of age-related sarcopenia and BMI in older adults require deeper study, WC may better characterize the impact of obesity on myocardial ageing.