Grehlin concentrations correlate with hunger and craving ratings following oral ingestion of macronutrients
Objectives: We investigated the effects of oral ingestion of different nutrient solutions on olfactory, cognitive, metabolic and psychophysical function and the role of grehlin for the prediction of hunger and food craving. Experimental methods: Twenty healthy men participated in our study employing a double-blind, cross-over, repeated measurement design (four different study days). Each day participants received, one of three isocaloric (protein, carbohydrate or fat 600 kcal, 1,500mL) solutions or a placebo. Olfactory and cognitive tests were conducted three times per day. Psychophysical and metabolic function tests were performed 7 times on each examination day (observation period:−60min, 0 = solution intake, +60, +120, +180, +240, and +300min). Data were subjected to analyses of variance (ANOVA) with time and solution as within-subjects factors. Pearson correlation coefficients were calculated to estimate the correlation between ghrelin concentrations and their hunger and food craving. Results: Odorants were perceived as more unpleasant directly after ingestion of the macronutrient solutions. Ratings of hunger and food craving significantly differed over the observation period with lowest ratings following application of the protein solution. We observed a significant positive correlation of active grehlin with hunger and fat, protein and sweets craving for each nutrient solution. Active grehlin significantly correlated with carbohydrate craving for carbohydrate and fat solution and with vegetable craving for fat solution only. Conclusions: The significant correlations of active ghrelin concentrations with hunger and craving ratings recommend ghrelin as predictor of these physiological measures. Funding: This investigation was made within the Neurotrition project, which is supported by the FAU Emerging Fields Initiative.