Total body water as an index for predicting body fat in rats

The determinations of total body water, body density, surface area and Lee index were carried out on 15 live Sprague-Dawley rats. The rats were subsequently sacrificed and subjected to carcass analysis by desiccation, gravimetry and ether extraction of body fat. The results of multiple regression using the maximum R2 improvement technique indicated that a strong correlation existed only between body fat and total body water which was statistically significant (P = 0.0001). The regression equation representing such a relationship was % of body fat = 83.167-1.067 X (% total body water). The % body fat computed from density, multiple regression models, and the actual fat content of carcass were not significantly different by the Newman-Keuls range test. The validation of the predicting equation was done using lean and obese Zucker rats. It was found that the predicting equation overestimated body fat by 0.67% for lean rats and underestimate 1 body fat of obese Zucker rats by 3.57%.