Clinical Relevance for the Veteran The relationship between energy expenditure and lean tissue in monozygotic twins discordant for spinal cord injury

Purpose of the Work. The objective of this study was to determine energy expenditure and fat-free mass (FFM), as well as the relationships between these parameters, in persons with spinal cord injury (SCI). Subjects and Procedures. Thirteen pairs of monozygotic twins discordant for SCI were studied. Basal energy expenditure (BEE) and resting energy expenditure (REE) were determined by indirect calorimetry. Measurements for FFM and fat mass were obtained by dual-energy x-ray absorptiometry. Total body potassium (TBK) was determined by a wholebody counting chamber. Values are expressed as mean ± standard deviation. Results. BEE and REE of the twins with SCI were significantly less than the able-bodied cotwins (1387 ± 268 vs. 1660 ± 324 kcal/d, p < 0.005, and 1682 ± 388 vs. 1854 ± 376 kcal/d, p < 0.05, respectively). Regardless of the group, direct and highly significant relationships were evident among BEE or REE and FFM or TBK. Thus, twins with SCI had lower energy expenditure than their able-bodied co-twins. Regardless of paralysis, direct linear relationships existed between energy expenditure and measures of lean mass. Relevance to the Veteran Population. For the maintenance of body weight, the caloric content of the diet should be directly related to energy expenditure. In persons with SCI, lean mass is reduced, and the magnitude of this reduction is directly related to energy expenditure. Because the relationship of lean mass to energy expenditure is similar in those with SCI and able-bodied persons, the prescription of energy needs for individuals with SCI may be computed if a surrogate measure of body composition providing a measure of lean tissue is employed. William A. Bauman, MD