Fifty healthy volunteers were randomly assigned to two groups and were fed an isocaloric breakfast (464 kcal) containing high GI (HGI; GI = 90) or low GI (LGI; GI = 47) components. Serum motilin, orexin, and NPY concentrations were measured before (0 h) and 2 h after the meal.
The concentrations of motilin, orexin-A, NPY, C-peptide, and blood glucose at 0 h were similar in both groups of subjects. However, 2 h after breakfast, the serum motilin, NPY, C-peptide, and blood glucose concentrations were increased and orexin-A concentrations were decreased in both groups. The percentage changes from 0 to 2 h [(2-h value 鈭?#xA0;0-h value)/baseline 脳 100)] in motilin (27.72 卤 2.46%vs. 20.95 卤 2.06%, p = 0.04) and orexin-A (9.15 卤 2.06%vs. 3.49 卤 1.67%, p = 0.038) concentrations were significantly higher in the LGI group than in the HGI group. By contrast, the percentage changes in NPY (53.7 卤 9.73%vs. 28.1 卤 5.2%, p = 0.026) and blood glucose (12.3 卤 3.78%vs. 1.77 卤 2.52%, p = 0.025) concentrations were significantly greater in the HGI group than in the LGI group. Although C-peptide concentrations increased significantly after breakfast in both groups, the magnitude of the increase was similar (132.69 卤 25.15%vs. 139.98 卤 27.29%, p = 0.845). Motilin and NPY concentrations were moderately positive correlated (r = 0.410, p = 0.042), while orexin-A and NPY concentrations were negatively correlated (r = 鈭?.429, p = 0.033) at 2 h in the LGI group.
A breakfast with a LGI reduced the secretion of orexin-A but significantly stimulated motilin secretion, without marked effects on the secretion of NPY. Therefore, consumption of a LGI diet may help to regulate food intake and energy expenditure in healthy individuals based on the changes in these hormones.