Gastric test meals of Polycose, with volumes of 300, 400, and 600 ml and energy densities of 0.5, 0.7, 1.0, 1.3, 1.5, and 2.0 kcal/ml, were given to 21 men and recovered after 30, 60, or 120 min. Polycose, a polymer of glucose, was chosen as a soluble homolog of food. The results of 1134 Polycose meals were analyzed in terms of the rates of energy delivery to the duodenum. The rates of emptying in the initial 30 min were significantly greater than in either the 30-60- or 60-120-min periods. Increases in either energy density or meal volume increased the rate of energy delivery in all time periods (p less than 0.001). The steady rate of energy delivery, which was evident after the initial 30 min, was correlated with increases in the initial meal volume and energy density, such that doubling the volume of meals from 300 to 600 ml increased the rate of emptying by a mean of 0.72 kcal/min, whereas doubling the energy density of the meals from 0.7 to 1.3 kcal/ml raised the rate of emptying by 0.62 kcal/min, with an overall mean rate of caloric emptying of 2.5 kcal/min. Thus, increases in either the initial volumes or the energy densities of the test meals significantly increased the rate of acceptance of energy by the duodenum.