Gastric emptying, CCK release, and satiety in weight-stable obese subjects

Scintigraphic gastric emptying studies are far from conclusive in obesity. The aim was to investigate gastric emptying and CCK release in weight-stable obese subjects on their usual diet and to study the impact of factors known to determine gastric emptying. Patients entering a weight reduction program were asked to participate in a study examining gastric emptying by scintigraphy and CCK release in response to a meal with questionnaires on feelings of satiety. Forty-five patients (9 M, 36 F) with a mean (SD) BMI of 37.0 (4.0) kg/m2 entered the study. The mean T50 (emptying of 50%) of fluids was 20.7 (10.3) min, and that of solids 141.9 (168.3) min. The percentage emptying of solids was 34.5 (19.9)%/hr. CCK values peaked within 42 min and paralleled the subjective ratings of satiety but did not correlate with gastric emptying. Five of 45 subjects (11%) had very prolonged gastric emptying of solids; they showed higher caloric intakes and higher insulin levels. They did not differ in CCK values and ratings of satiety but scored higher in being active and awake. Without these five subjects the T50 of solids was 94.3 (36.1) min, and the percentage of emptying 37.9 (18.4)%/hr. Liquid emptying was faster and solid emptying similar compared with those of normal-weight individuals. Height, fat-free mass, and waist-hip circumference were positively related to solid emptying. In weight-stable obese subjects liquid emptying was faster and solid emptying similar to those in normal-weight subjects. Higher caloric intakes and insulin levels were present in subjects with prolonged solid emptying; they also appeared more vigilant. Body size and composition were the only determinants suggesting a faster solid emptying in taller and muscular subjects or in subjects with more intraabdominal fat.