Abstract
OBJECTIVES: The glucostatic theory of appetite suggests that changes in blood glucose determine hunger and food intake behavior. While, this is the most popular theory to date it is not without controversy. Our goal was to evaluate this theory in an acute buffet meal challenge setting. METHODS: Overweight and obese (BMI: 32.9 ± 2.6 kg/m(2)) men and women (n = 21 and 50 respectively) were tested in a daylong satiety protocol. After an overnight fast, blood draws and self-reported visual analog scores for appetite questions were obtained at the following times: 2 times at fasting, 5 times after a breakfast meal providing 25% of energy need, and 12 times after a lunch meal with 40% of energy need 4 h after breakfast. Satiety hormones (plasma insulin, ghrelin, amylin, PYY, CCK, GIP and GLP-1) and plasma glucose and triglycerides were measured. A buffet dinner was offered beginning 4 h after lunch and participants self-selected the time and duration for this meal. The inter-meal interval between dinner and buffet consumption duration were recorded, as well as the amount of food consumed during the buffet. Boosted random forest models were used to identify factors that were best at predicting self-reported hunger, fullness, amount of buffet food consumed, and inter-meal interval. RESULTS: The inter-meal interval was 288.6 ± 36.8 min. The total energy consumed at the dinner buffet was 1482.4 ± 545.8 kcals. The random forest model identified that GLP-1, amylin, triglycerides, PYY and insulin were the top 5 predictors of both calories consumed during buffet (training R(2 )= 0.551, validation R(2 )= 0.249, test R(2 )= 0.278), as well as the inter-meal interval (training R(2 )= 0.577, validation R(2 )= 0.354, test R(2 )= 0.316.)Glucose and insulin were the primary predictors of self-reported hunger (training R(2 )= 0.638, validation R(2 )= 0.358, and test R(2 )= 0.248) and fullness (training R(2 )= 0.666, validation R(2 )= 0.406, and test R(2 )= 0.349). CONCLUSIONS: While the glucostatic theory may hold true while predicting self-reported hunger and fullness, it is not the primary predictor of how long a person stays full, or how much food is consumed in a buffet type setting. Hedonic cues may dominate physiological signals while exposed to buffet-style settings. FUNDING SOURCES: National Dairy Council (Dairy Research Institute); Dairy Council of California; USDA, ARS 5306-51530-006-00D and 5306-51530-016-00D.