The effect of a carbohydrate oral rinse on energy expenditure in a fed state in individuals with high and low sensitivity to carbohydrate taste

Twenty participants will complete a randomised crossover study that investigates participants’ energy expenditure and substrate (carbohydrate and fat) oxidation after drinking a beverage containing 50g of maltodextrin followed by sensory stimulation with a maltodextrin, glucose or water (control) solution. There will be 3 x 3 hour test sessions in total for each participant, with a washout period of at least 3 days. Test sessions will take place in Deakin University's clinical laboratories. Measurements will be taken at approximately the same time for all 3 test sessions. Participants will be asked to adhere to the following guidelines the day before test sessions: eat a dinner that is the type and amount they would usually eat, keep their usual physical activity level, avoid high intensity exercise, and fast overnight (8-12 hours). On the day of test sessions, participants will arrive after their overnight fast, voided urine. They will first undertake anthropometry measurements. Body weight and composition will be measured using a body composition analyser (Tanita BC-418). Height will be measured using a portable stadiometer. They will then rest for 30 minutes before having their REE measured using an indirect calorimeter (Quark RMR). The measurement involves the placement of a transparent hood over the upper body of participants, which is connected to gas analysers that measure oxygen consumption and carbon dioxide production. Following this, participants will drink a carbohydrate drink containing 50 g of maltodextrin within 3 minutes. This will be immediately followed by oral stimulation with a maltodextrin solution (carbohydrate taste), glucose solution (sweet taste) or de-ionised water (control) using the “sip and spit” method for 45 seconds. Gaseous exchanges will be measured for the next 90 minutes to determine energy expenditure and substrate oxidation using the hooded indirect calorimeter. Participants are allowed to watch the television during the measurement. A researcher will be present at all times during the test session in order to monitor adherence to the intervention. The indirect calorimeter will be calibrated prior to each test session to ensure accuracy of readings. Respiratory quotient (RQ) will be calculated as a ratio of carbon dioxide production to oxygen consumption. Oxygen consumption and carbon dioxide production will be used to calculate energy expenditure using Weir equation and substrate oxidation (carbohydrate and fat) rates using Frayn equations.