Background: Recently, the particular interest is
on ghrelin, the dietary control factor among many
scientists and it a toxic diurnal variations has been
demonstrated before and after meal. However, the
experimental approach has been only to see the
changes in the concentration of ghrelin after intake
of meals standardized with fixed calories at
scheduled meal hours. The authors of this particular
experiment have tried to observe and record the
changes in concentrations of plasm ghrelin of
persons with different breakfast hours. This might
help in providing a basis for further possible studies
in outpatient setting.
Method: A group of four relatively healthy males
whose ages between 23.4 and 35.5 with prior
agreements were selected for this study. After body
measurements, body lipid status was measured based
on Lunar prodigy (GE medical systems, Waukesha,
Wisconsin, USA) which is also referred to as
DEXA. All of the selected persons had somewhat
fixed breakfast time; however, they were asked to
strictly keep their breakfast time fixed and steady
starting two weeks before the beginning of
experiment. The bloods of those who skip their
breakfast without any particular stress were sampled
at 6:30 AM, whereas the rest had different schedule,
whose bloods were sampled every hour starting 1
hour before the first meal of the day till just before
lunch (11:30 AM). From each blood sample, the
level of plasma ghrelin was measured using the
commercial radioimmune assay (Phoenix Pharmaceuticals,
Inc., Belmont, CA). Leptin was measured
with double antibody radioimmune assay using I-125
labelled leptin, plasma insulin with radioimmune
assay using antibody attachment tube, and blood
sugar with Synchron LX20 (Beckman Coulter, Inc,
Fullerton, USA) using glucosylation enzyme method.
Result: The body mass index of the volunteers
was 22.9∼27.1 kg/m2, with 80.3∼93.3 cm waist
circumference. Based on measurements by DEXA, the rates of total body lipid and trunk lipid were
each 27.1∼31.8% and 32.7∼32.4%, respectively.
The concentrations of plasma ghrelin of those who
consume their breakfast before and 2 hour after their
breakfast are 113.0∼800.0 pg/mL and 78.3∼553.0
pg/mL. The concentrations of leptin are 4.9∼5.1
ng/mL and 4.4∼4.7 ng/mL. Compared to the
cocentration of plasma ghrelin and of leptin recorded
just before breakfast, it showed 7.2∼30.9% and 7.
8∼10.2% decrease, respectively, 2 hours after
breakfast. For those who skip their breakfast, the
plasma concentration of ghrelin was recorded the
lowest at 7:30 AM, even though there was no
change in insulin and blood sugar. The rest of the
subjects had their lowest plasma ghrelin concentration
at 2 hours after breakfast, despite their
different meal schedule.
Conclusion: The persons with different breakfast
hours had their lowest plasma concentration of
ghrelin at 2 hours after breakfast. In contrast, the
persons who skip their breakfast had their lowest
concentration at 7:30 AM.

Keywords: Peptide, Leptin, Insulin, Meal, Radioimmune assay