Review of Macronutrient Metabolism Group workshop.

Dr Marinos Elia (Cambridge) described the theoretical basis of compartmental analysis of body composition. Classically the body has been considered to be composed of fat and fat-free tissue. Fat is a relatively homogeneous compartment but fat-free mass (FFM) includes water, protein, bone, glycogen and small amounts of other constituents. He described how increasingly sophisticated methods of body composition analysis attempted to make measurements of each of these compartments of the body in order to re-assemble the components of body weight, without making assumptions about the relationship of one constituent to another, as required in traditional two-compartment models (Elia, 1992). He also described how some of the methods employed in body composition analysis were increasingly finding use outside this narrow field. In particular, he referred to work on bioimpedance tomography (Brown et al. 1994). This can be used to produce images of specific regions of the body, including heart, lungs and brain throughout cycles of activity, and to pinpoint specific abnormalities in these tissues. He suggested that further breakthroughs in both the measurement of body composition and scanning techniques, such as bioimpedance tomography, are most likely to come from physicists, but that input from nutritionists and clinicians would be essential in order to ensure that the greatest progress was made in producing answers to biologically-relevant issues.