Gastric Emptying of Solids and Semi-solids in Morbidly Obese and Non-obese Subjects: an Assessment Using the 13C-octanoic Acid and 13C-acetic Acid Breath Tests

Background: It has been suggested that obesity is associated with an altered rate of gastric emptying. The objective of the present study was to determine whether the rates of solid and semi-solid gastric emptying differ between morbidly obese patients and lean subjects.

Methods: The Gastric-emptying time (GET) of solid and semi-solid meals were compared between lean healthy subjects and morbidly obese patients enrolled in two previously published studies. GET of solid and semi-solid meals was measured using the 13C-octanoic acid breath test and 13C-acetic acid breath test, respectively, in 24 lean and 14 morbidly obese individuals of both sexes. Student t-test was used to compare the mean data between the lean and morbidly obese groups. The influence of sex, gender, BMI and morbid obesity on the GET of solid meals was verified by linear regression analysis.

Results: Mean t(1/2) values of solid GET (+/- standard deviation) were 203.6 +/- 76.0 min and 143.5 +/- 19.1 min for lean and obese subjects, respectively (P = 0.0010). Mean t(lag) values of solid GET were 127.3 +/- 42.7 min and 98.4 +/- 13.0 min for lean and obese subjects, respectively (P = -0.0044). No significant difference in semi-solid GET was observed between the lean and morbidly obese groups.

Conclusion: The present study demonstrated a significantly enhanced gastric emptying of the solid meal test in morbidly obese patients when compared to lean subjects. This finding is compatible with the hypothesis that rapid gastric emptying in morbidly obese subjects increases caloric intake due to a more rapid loss of satiety.