Assessing fat mass from a body composition perspective: a critical review

The estimation of fat mass and fat percentage has been used both in the field of health, due to its relationship with various diseases; and in sport, due to its relationship with sports performance. However, the advantages and disadvantages of the different methods of estimating body composition are rarely taken into consideration when evaluating this parameter, including dual energy X-ray absorptiometry (DEXA or DXA); hydrodensitometry; air displacement plestimography; electrical bioimpedance; anthropometry; 2D/3D/4D scanning and ultrasound, as well as whether they are indirect or dual indirect methods. Nor do most studies and evaluations take into consideration the different models from which body composition can be approached, with methods that use a chemical, molecular, cellular, tissue or segmental approach, the most commonly used being the molecular and tissue models. All this leads to the fact that the different methods can be used to estimate adipose mass, fat mass and lipid mass. Although these concepts have been treated as synonyms, there are differences among them that are addressed in this article, as well as what the different assessment methods estimate: lipid mass or adipose mass. It concludes with the practical implications of all the above for fat mass estimation.