Developing and cross-validation of new equations to estimate fat mass in Italian population.

Obesity is a global burden that involves more than 500 million people. The objective of this work is to develop and cross-validate the new sex-specific equations to estimate fat mass, based on anthropometric parameters and to compare with other equations. We evaluated 38762 subjects by dual-energy X-ray absorptiometry (DXA) and enrolled 1434 women and 640 men, aged between 18 and 65 years. Then, we randomized 480 men and 1080 women in developing set and 160 men and 354 women in the cross-validation set. Statistical analysis as multiple regression and Bland-Altman methods were performed. Sex-specific equations were created based on developing set. Then, based on the cross-validating set, these equations were validated and were observed to agree with fat mass by DXA, better than other equations, such as BAI and RFM. These new sex-specific equations represent an easy tool, since they require only two circumferences, to be used in clinical practice. In the next future, these equations could be validated and refine on specific Italian sub-populations, divided by gender and age, such as the military.