Aging, energy expenditure and nutritional status: evidence for denutrition-related hypermetabolism

Resting energy expenditure (REE) and nutritional status have been evaluated in 39 elderly inpatients (mean age 84.0 +/- 6.9 years). The nutritional status declined with aging as shown by significant negative correlations between age and, respectively, weight (p < 0.001), fat free mass (FFM) (p < 0.01) and body mass index (BMI) (p < 0.01). The best prediction for REE when considering the whole population was given by FFM (p < 0.001). Increased REE was observed in patients after recent surgery, related to an inflammatory state, as shown by increased plasma levels of C-reactive protein and orosomucoid. Irrespectively of the inflammatory state, REE was also found to be related to the nutritional status: patients who showed a BMI < 20 had higher REE than patients with a BMI > 20 (28.4 +/- 1.3 vs. 22.1 +/- 0.7 kcal/kg of body weight; p < 0.001; 35.7 +/- 1.6 vs. 30.9 +/- 1.0 kcal/kg of FFM; p < 0.02). These results increasingly suggest that elderly patients may suffer from denutrition relevant to hypermetabolism.