Changes in gut hormone and glucose concentrations in relation to hunger and fullness

BACKGROUND: The search for biomarkers of appetite is very active. OBJECTIVES: The aims were to compare dynamics of hunger and fullness ratings on a visual analog scale (VAS) with dynamics of glucagon-like peptide 1, peptide tyrosine-tyrosine, ghrelin, glucose, and insulin concentrations throughout different meal patterns-and thus different timings of nutrient delivery to the gut-by using a statistical approach that focuses on within-subject relations of these observations and to investigate whether appetite ratings are synchronized with or lag behind or in front of changes in hormone and glucose concentrations. DESIGN: Subjects (n = 38) with a mean (±SD) age of 24 ± 6 y and BMI (in kg/m(2)) of 25.1 ± 3.1 came to the university twice for consumption of a 4-course lunch in 0.5 or 2 h (randomized crossover design). Per subject regression slopes and R(2) values of VAS scores on hormone and glucose concentrations were calculated. We tested whether the means of the slopes were different from zero. Regarding possible lags in the relations, the analyses were repeated with VAS scores related to hormone and glucose concentrations of the relevant previous and following measurement periods. RESULTS: VAS scores and hormone and glucose concentrations changed synchronously (P < 0.005, R(2) = 0.4-0.7). Changes in ghrelin concentrations lagged behind (10-30 min) changes in hunger scores (P < 0.005, R(2) = 0.7) and insulin concentrations (P < 0.005, R(2) = 0.6), which suggests a role for insulin as a possible negative regulator of ghrelin. No major differences in slopes and R(2) values were found between the meal patterns. CONCLUSIONS: This method may be useful for understanding possible differences in relations between VAS scores and hormone and glucose concentrations between subjects or conditions. Yet, the reported explained variation of 40% to 70% seems to be too small to use hormone and glucose concentrations as appropriate biomarkers for appetite, at least at the individual level and probably at the group level. This study started in 2007, which means that it was not registered as a clinical trial.