Body composition during the first year of life

Knowledge of changes in body composition is of great potential benefit to the understanding of the nutritional needs and functional outcome of nutritional management for both healthy and sick infants. This review evaluates the different methods presently available to evaluate whole-body composition analysis based on different models, i.e. 2, 3, or more compartments. Analysis of the various approaches related to age, body weight and body length suggests that the major differences observed between the techniques could be preferentially related to differences in the population and that gender is one of the major determinants of whole-body composition during the first year of life. Among the techniques dual-energy X-ray absorptiometry (DEXA) and, more recently, air displacement plethysmography appear to be major techniques that have been evaluated in infants. Determination of weight gain composition is one of the major keys to the evaluation of the nutritional requirements, whereas the dynamic aspect during the first years of life could play a fundamental role in the nutritional programming of adult morbidity. Recent data suggest that protein intake and the protein:energy ratio are the main determinants of weight gain composition in preterm infants. Nevertheless, these data need to be confirmed in larger cohorts evaluated during the first year of life. To that, DEXA appears to be a useful technique to obtain sequential analysis of weight gain composition over a longer period of time and in a less invasive fashion.