Effect of two fasting periods of different duration on ghrelin response to a mixed meal.

The inhibitory effect of food on ghrelin secretion is reduced in several eating disorders such as restricting type anorexia nervosa, bulimia and obesity. These conditions are frequently characterised by irregular distribution of meals during the day. It is unknown whether two short fasting periods different duration affect ghrelin response to a mixed meal. Aim of the present study was to examine, in healthy volunteers, the effects of two fasting periods of different duration on pre- and post-prandial ghrelin concentrations after a standard mixed meal. Methods and results: Nine healthy men (mean ageGS.E.M., 25.1G0.2 years; mean body mass indexGS.E.M., 22.6G0.3 kg/m2) were studied in 2 days after 12 h of fasting (12F) and 17 h of fasting (17F) with a within-subject repeated measure design. On both days they ate a standardized mixed meal. Before each meal hunger rating was evaluated with a visual analogue score. Blood samples for ghrelin, insulin, and glucose were collected at 0, 45, 60, 90, 120, 150 and 180 min after meal. Comparing fasting values of 17F with 12F there was a significant increase in plasma ghrelin (160G20 vs. 146G18 fmol/mL, PZ0.015) and hunger rating (evaluated with a visual analogue scores) (7.0G0.3 vs. 5.1G0.4, P!0.003). A positive correlation between fasting ghrelin and hunger rating (rZ0.52, P!0.01) was found. Circulating ghrelin decreased after both meals without any significant difference in relation with the previous length of fasting. Also postmeal ghrelin AUC as well as fasting and postmeal concentrations of insulin and glucose were similar after 12F and 17F. Conclusions: In healthy subjects a longer fasting period increases ghrelin concentration but did not affect post-prandial ghrelin response to a mixed meal.