Captive elephant populations are not self-sustaining due to health concerns possibly related to obesity. Categorizing obesity relies on qualitative analyses like body condition scores (BCS). However, elephant indices have not been validated against measured body composition. The objective was to compare BCS systems to body composition determined by deuterium dilution in 28 zoo-kept Asian elephants. Elephants were weighed and given deuterated water orally (0.05 ml/kg). Blood was collected at ~0, 24, 120, 240, 360, and 480 hr after dosing. Photographs were taken to score the elephant based on four BCS systems (BCSWemmer [0 to 11 scoring], BCSMorfeld [1 to 5 scoring], BCSFernando [0 to 10 scoring], BCSWijeyamohan [1 to 10 scoring]). Based on regression analysis, relative fat ranged from −305 kg to 515 kg, where negative values indicate less and positive values indicate more fat than expected for the elephant's mass in this population. BCSFernando was associated with relative fat (p =.020, R2 = 0.194). Relative fat, adjusted for sex and age in the statistical model, was associated with BCSWemmer (p =.027, R2 = 0.389), BCSFernando (p =.002, R2 = 0.502), and BCSWijeyamohan (p =.011, R2 = 0.426). Inclusion of zoo and familial relatedness resulted in all BCS systems associated with relative fat (p ≤.015). Only BCSFernando predicted relative fat, unadjusted, suggesting it is the most capable system for practical use. Compared to absolute fat, relative fat may be more biologically relevant as greater fat relative to body mass is more likely to lead to health issues.