The greater the concentration of energy (kcal/ml) in the gastric contents, the less is the volume rate of transfer per minute to the duodenum. Two sets of duodenal receptors are involved, one stimulated by the osmotic properties of the digestion products of carbohydrate and protein and one by the digestion products of fat. All three food stuffs slow gastric emptying equally when their concentration is expressed as kilocalories per mililiter. Doubling the energy density of food from 0.7 to 1.4 kcal/ml increased the transfer from 116 to 176 kcal/30 min (50% instead of to 232 kcal/30 min had there been no slowing of gastric emptying. Changing the energy density of formula feedings given to infants from 0.7 to 1.4 kcal/ml increased their food intake by 50%. A tendency to choose diets with a high energy density is characteristic of persons with relatively high weight-to-height ratio. It seems possible that the regulation of gastric emptying and the control of food intake have components in common and that rapid gastroduodenal transfer of energy may be associated with high food intake.