Learning about the energy density of liquid and semi-solid foods

BACKGROUND: People learn about a food's satiating capacity by exposure and consequently adjust their energy intake. OBJECTIVE: To investigate the effect of energy density and texture on subsequent energy intake adjustments during repeated consumption. DESIGN: In a randomized crossover design, participants (n = 27, age: 21 +/- 2.4 years, body mass index: 22.2 +/- 1.6 kg m(-2)) repeatedly consumed highly novel foods that were either low-energy-dense (LE: 30 kcal per 100 g) or high-energy-dense (HE: 130 kcal per 100 g), and either liquid or semi-solid, resulting in four product conditions. In each condition, a fixed portion of test food was consumed nine times as an obligatory part of breakfast, lunch and dinner on 3 consecutive days. All meals continued with an ad libitum buffet; food items for evening consumption were provided and the intake (kcal per day) was measured. RESULTS: Buffet intake depended on energy density and day of consumption of the test foods (day*energy interaction: P = 0.02); daily buffet intake increased from day 1 (1745 +/- 577 kcal) to day 3 (1979 +/- 567 kcal) in the LE conditions; intake did not change in the HE conditions (day 1: 1523 +/- 429 kcal, day 3: 1589 +/- 424 kcal). Food texture did not affect the intake (P = 0.56). CONCLUSIONS: Intake did depend on energy density of the test foods; participants increased their buffet intake over days in response to learning about the satiating capacity of the LE foods, but did not change buffet intake over days when repeatedly consuming a HE food as part of their meal. The adjustments in intake were made irrespective of the food texture.