["In vivo" body composition assessment; part I: a historic overview]

The study of body composition (BC) has gained in relevance over the last decades, mainly because of its important health- and disease- related applications within both the clinical and the sports setting. It is not a new area, and its especial relevance as an area of biology dates from the second half of the nineteenth century. In this paper, we have reviewed the three historic periods of BC, with special reference to the most important advances in in vivo assessment. Even though the earliest findings about human BC date from antiquity, the first (or 'early') stage of discovery began in 1850. Said early stage was mainly characterized by data obtained from the dissection of cadavers and by the application of biochemical methods in vivo. Longitudinal changes in body composition were also a concern. The second (so called 'recent') stage, in the second half of the twentieth century, was marked by milestones such as the formulation of the first mathematical models for the estimation of body components, and technological advances. Within the third ('contemporary' or 'current') stage of research, several groups have focused on validating the classical BC models in specific populations, on analysis of the genetic determinants (i.e. phenotypes and, more recently genotypes) of body composition, and on re-instigating the study of dynamic BC.