BACKGROUND & AIMS: Ghrelin is secreted by the stomach and stimulates food 
intake. Obese individuals have lower fasting plasma ghrelin levels but increased 
appetite, suggesting greater responses to endogenous ghrelin in obesity. The aim 
of this study was to compare effects of exogenous ghrelin (at a dose that 
stimulates growth hormone [GH] release in the physiologic range) versus placebo 
on gastric emptying, gastric volume, and postprandial symptoms and determine 
whether body mass (ranging from normal weight to obesity) influences responses 
to ghrelin.
METHODS: After intravenous bolus synthetic human ghrelin (0.33 mug/kg) or 
saline, we measured plasma GH, gastric volume, and gastric emptying by combined 
(99m)Tc-single-photon emission computed tomography and scintigraphy ((111)In egg 
meal, 300 kcal) and postprandial symptoms using visual analogue scales.
RESULTS: In 25 obese subjects (5 men and 20 women; body mass index [BMI], 36 +/- 
4 kg/m(2)) and 13 female normal-weight (BMI, 22 +/- 2 kg/m(2)) subjects of 
similar ages, ghrelin increased GH levels (15.0 +/- 2.4 ng/mL) at 40 minutes 
postinjection and tended to decrease fasting gastric volumes compared with 
placebo (P = .059). There were no effects of BMI on treatment response and no 
differences between ghrelin and saline on postprandial (P = .09) or change in 
(postprandial minus fasting) gastric volumes, gastric emptying, or aggregate 
postprandial symptoms. Effects of ghrelin did not differ between obese and 
normal-weight participants.
CONCLUSIONS: At doses that stimulate physiologic GH plasma levels, synthetic 
ghrelin tended to decrease fasting gastric volumes without altering postprandial 
volumes or gastric emptying in a predominantly female cohort. The data are not 
consistent with the hypothesis that higher body mass is associated with 
increased gastric responsiveness to ghrelin.