Post-prandial plasma ghrelin levels in people with different breakfast hours

OBJECTIVES: To investigate the changes in post-meal plasma ghrelin levels in people with different breakfast hours. DESIGN AND INTERVENTIONS: The subjects adhered to strict breakfast times starting 2 weeks before the study. Blood was drawn hourly from 0530 or 0630 until 1130. Plasma ghrelin, leptin, and insulin levels were measured by radioimmunoassay. SETTING: Medical Research Institute, Pusan National University Hospital, Korea. SUBJECTS: A total of 16 healthy volunteers. RESULTS: The mean plasma ghrelin level in subjects consuming breakfast was 548.7 +/- 239.6 fmol/ml before breakfast and 384.8 +/- 168.7 fmol/ml 1 h after breakfast, with leptin levels of 6.8 +/- 2.6 and 6.5 +/- 2.5 ng/ml, respectively. Plasma ghrelin levels were lowest 1 h after the meal, although the breakfast times differed. The plasma ghrelin level was lowest at 0730 in subjects not eating breakfast. CONCLUSIONS: These findings suggest that the plasma ghrelin levels are lowest 1 h after breakfast despite the variance in breakfast times. This timing might best reflect an individual's plasma ghrelin level and enable reasonable comparisons.