Introduction

There is increasing evidence that poor or excess nutrition during infancy and early childhood may be associated with increased risks for adverse health effects later in life. Postmenopausal osteoporosis, for example, can be viewed as a disease with a “pediatric origin” related to suboptimal mineralization of the skeleton during growth. Likewise, there is increasing interest in the association between body composition during infancy and the incidence of adolescent and adult obesity. For many years, the assessment of an infant's growth has been based on the measurement of body size (i.e., weight, length, body circumferences) and occasionally skinfold thicknesses. These indices have been very useful in our understanding of general growth on a population basis, but are usually too crude to distinguish significant changes in body composition for the individual infant except at the extremes of abnormal weight. Over the last several decades, a number of noninvasive techniques for the in vivo assessment of human body composition have been developed, and recently reviewed. In most cases, the instruments used for these assays have been designed for use in adults, and it is only more recently that these technologies have been extended to the examination of pediatric populations.

The term “body composition” will have different meanings depending on one's own scientific background, experience, and interest. It can refer to the chemical makeup of specific tissues, organs, or the whole body, or it may be viewed from the prospective of physiological function or anatomical structure.