To determine the efficacy of bioactive molecules for minimizing body fat accretion in mammals, an effective method for measuring changes in body fat must be used. In the current study, the precision and accuracy of the Dual Energy X-ray Absorptiometry (DEXA) estimates of the weight and tissue (fat, lean and bone mineral) content of two body depots (carcass and internal organs) were evaluated in heavy weight pigs (133-265 kg) serving as an obesity development model.

DEXA accurately estimated carcass weight, but underestimated the fat tissue contents and overestimated the lean tissue contents of both the carcass and organ depots relative to those estimated from chemical analysis of the fat and protein contents of the depots. However, DEXA precisely detected changes in carcass and organ depot weights (R2 = .99, .99 respectively) and less precisely detected changes in the depot’s chemically determined fat (R2 = .95, .73) and protein content (R2 = .88, .84). Specifically, for each 1 kg change in carcass and organ depot weights, DEXA predicted the changes with a 95 % confidence (2 SE of estimate) within ± .008 and .026 kg, respectively. For each 1 kg change in the two depot’s chemically determined fat content, DEXA predicted the change within ± .092 and .338 kg, respectively. In conclusion, DEXA is a method that can precisely detect changes in body composition in large, heavy weight pigs being used in a model of obesity development. I