This study was done to determine the relative effects of energy content and weight of ingested food on subsequent satiety and food intake. The weight/volume and the energy content of nine preloads were manipulated, in a 3 x 3 factorial design, to give three weight levels, 250, 500 and 750 g, and three energy levels 0, 1.26 and 2.51 MJ (0, 300 and 600 kcal). The weights were varied by the addition of water, while the energy levels were varied by using yogurt and cream. Each of the 1.26 and 2.51 MJ preloads contained 27 g of protein and 31 g of carbohydrates. The 1.26 MJ preloads contained 8 g of fat and the 2.51 MJ preloads had 41 g of fat. Each of the nine preloads was presented as a lunch to 21 female and 16 male subjects. Two hours after the preloads, subjects consumed sweet and savory snacks and various drinks ad libitum from a buffet. The weight of the preload had a small but statistically significant effect on feelings of hunger and satiety between preload and buffet, and on energy intake during the buffet (5.34, 5.05 and 5.04 MJ after 250, 500 and 750 g preloads). There was a large difference between 0 and 1.26 MJ, but little difference in effect between 1.26 and 2.51 MJ preloads. Mean energy intakes in the buffet after the 0, 1.26 and 2.51 MJ preloads were 6.17, 4.83 and 4.42 MJ. These results suggest that the weight or amount of food affects subsequent appetite and food intake, but the effect of energy is stronger.