Effect of Mixed Solid Food and Water Intake on Blood Glucose Level and Energy Metabolism

Carbohydrate-rich solid foods, such as bread, pasta, and steamed rice, are applied for test meals in studies examining digestion and absorption of food related to glucose metabolism and sports science. Such research must consider that drinking water is sometimes better as it avoids the risk of choking or aspiration. However, the water increases test meal volume and dilutes glucose concentration, which may influence the digestion and absorption of ingested foods, as well as energy metabolism. Therefore, this study aimed to investigate whether the peak time and concentration of glucose and energy metabolism will differ among the intake of steamed rice alone (Rice), simultaneous intake of steamed rice and water (Mixed), and water alone (Water). Following the intake of the test meals, there was an immediate increase in blood glucose in Mixed compared to Rice and Water. The glucose peak time of Rice (60 (56-68) min; median and quartile) was also delayed compared to Mixed (38 (29-45) min). The blood lactate peak time was also significantly different in Mixed and Rice. Although meal and time interaction was not found in energy expenditure, Mixed increases the respiratory quotient by 40 min compared to Water. In conclusion, this study demonstrated that simultaneous intake of steamed rice and water hasted digestion and absorption of glucose and activates glycolysis. Future studies investigating gastric emptying rate and glucose metabolism should ensure that the conditions of fluid intake and the test meal volumes are consistent and do not differ significantly.