Hypocaloric parenteral nutrition support in elderly obese patients

Hypocaloric nutritional support has been successfully used to achieve positive nitrogen balance in obese patients. However, advanced age is associated with changes in substrate metabolism. To evaluate the efficacy of this practice in elderly patients, we retrospectively reviewed 30 obese patients requiring parenteral nutrition support. Total caloric requirements (TCR) were calculated on the basis of the Harris-Benedict equation. Patients were given a minimum of 1.5 g/kg/day protein, 75 per cent of TCR when current body weight was >120 and < or =150 per cent of ideal body weight (IBW), and 60 per cent of TCR if current body weight was >150 per cent of IBW. The patients were divided into two groups: Group I (N = 18) patients were age <60 and Group II (N = 12) patients were > or =60 years of age. Only one of the Group I patients (143.2 +/- 25.7% IBW, received 18.2 +/- 3.7 kcal/kg/day and 1.6 +/- 0.4 g/kg/day protein), but five of the Group II patients (141.3 +/- 14.4% IBW, received 18.3 +/- 2.6 kcal/kg/day and 1.7 +/- 0.3 g/kg/day protein), had negative nitrogen balance (P = 0.025). Apparently, elderly obese patients have limited capacity to mobilize their fat stores as energy sources and may continue to undergo protein catabolism with hypocaloric high-protein nutrition support. Therefore, this form of nutritional support should be used with caution in elderly obese patients.