The specific nutritional consequences of malabsorption after small-bowel surgery were studied in a consecutive series of 48 ambulatory patients who had had small-bowel resection (n = 43) or bypass (n = 5) and in 10 patients who had an ileal pouch (n = 10). The patients received a 3-day standardized oral regimen providing daily 30 kcal/kg of ideal body weight (IBW). Throughout the study, 41 patients had malabsorption (fecal fat greater than 5%); 17 had fecal fat less than 5% and served as controls. The malabsorption patients absorbed 70% of protein and 71% of fat. Twenty-one were normonourished and 20 had features of mild energy malnutrition, vs. 15 and 2 controls, respectively. Compared with controls, malabsorption patients had decreased body weight and triceps skin-fold but no features of protein malnutrition. their mean daily food intake at home was significantly enhanced (39.6 +/- 13.1 kcal/IBW kg) vs. controls (28.8 +/- 5.8 kcal/IBW kg, P less than 0.001). In the malabsorption group, caloric intake was higher in the normonourished patients than in those with mild malnutrition. This study shows that a chronic malabsorption has limited nutritional consequences. The patients compensate for their absorptive handicap by increasing their oral intake.