Bread buns or slices? variations of bread shape modifies ad libitum intake of bread and toppings

The size and shape of foods are geometrical textural properties that have been shown to influence food intake. Changing shapes and sizes of carrier food such as bread influences the spreadable surface area and this may affect the amount of toppings used. In a cross-over study, 37 participants (11 males, 24 ± 7 years old, BMI of 23 ± 3 kg/m²) consumed three times an ad libitum breakfast consisting of either small buns (SB: 34 g per unit), large buns (LB: 47 g), or squared sandwich slices (SA: 36 g), similar in nutritional composition. Participants were free to use four kinds of toppings similar in energy density (2.3–2.4 kcal/g): apple syrup, jam, cream cheese, and egg salad. The ratio bread(g):topping(g) differed considerably (1:0.49 for SB; 1:0.53 for LB; and 1:0.63 for SA, p < 0.001), but total meal intake did not differ (g or kcal) p = 0.27. In sum, the meal with SA leads to relatively higher intake of toppings and lower intake of bread, whereas the meal with small buns (SB) leads to relatively lower intake of toppings and higher intake of bread. Changing surface areas by shapes of carrier foods can be used to manipulate the amount of toppings, condiments or sauces and thereby modulate the macronutrient and energy intakes within a meal or snack.