A comparison of postoperative metabolic and nutritional responses to different hypocaloric parenteral nutrition supports was performed in 42 patients with various gastric lesions. Sixteen patients (group A) received 3000 mL of a 5% glucose in water or glucose in saline infusion per day after surgery (approximately 10 kcal/kg per day). Another 14 patients (group B) received 2000 mL of 5% glucose in water or saline plus 1000 mL of 5% amino acid solution per day (approximately 10 kcal/kg per day and 1 g of protein per kilogram per day). The other 12 patients (group C) received 2000 mL of 5% glucose in water or saline plus 500 mL of 5% amino acid solution and 500 mL of 10% fat emulsion (approximately 20 kcal/kg per day and 0.5 g of protein per kilogram per day). After 7 days of study, all three groups were found to have a decrease in body weight, mid-arm circumference, triceps skin-fold, and serum albumin level, and the differences among them were not significant. Groups B and C had significantly less negative mean nitrogen balance than group A (-5.54 +/- 0.63 g/d and -6.07 +/- 0.49 g/d vs -9.20 +/- 0.68 g/d). Group B also had a significantly greater increase of transferrin (from 175.5 +/- 9.9 mg/dL to 185.4 +/- 9.3 mg/dL) than group A and a significantly greater increase in total lymphocyte count (from 956 +/- 113 cells/mm3 to 1196 +/- 176 cells/mm3) than groups A and C.(ABSTRACT TRUNCATED AT 250 WORDS)