This study examined the effects of four breakfast preloads of different sweetness and energy content on motivational ratings, taste preferences, and energy intakes of 12 obese and 12 lean women. The preloads consisted of creamy white cheese (fromage blanc) and were either plain, sweetened with sucrose or aspartame, or sweetened with aspartame and supplemented with maltodextrin. Their energy content was either 300 kcal (1,255 kJ) or 700 kcal (2,929 kJ). Motivational ratings of hunger and the desire to eat were obtained prior to and at 30 min intervals after breakfast. Taste preferences were measured prior to and 150 min after breakfast. The subjects ate buffet-style lunch, snack, and dinner meals in the laboratory. Obese women consumed significantly more energy at meals (2,596 kcal or 10,862 kJ) than did lean women (1,484 kcal or 6,209 kJ); derived a greater proportion of energy from fat (39.9% vs. 35.5%), and had lower dietary carbohydrate-to-fat ratios. Consumption of low-energy as opposed to high-energy breakfast preloads was associated with elevated motivational ratings by noon. However, energy intakes at lunch, snack, or dinner did not vary as a function of preload type, and no compensation was observed for the energy consumed at breakfast. Taste preferences were not affected by preload ingestion or by preload type. The study provided no evidence that aspartame promotes hunger or results in increased energy intakes in obese or in lean women.