Main study : four groups of subjects ( n = @ ; age @-@ years , BMI @-@ @ kgm ( -@ ) ) consumed @ml/@kcal foam ( based on pre-study results ) immediately after main meals ( M ) , after snacks ( S ) , in-between snacks and main meals ( I ) or not at all ( control , C ) within @ day of a reduced-energy meal plan consisting of three main meals and three snacks .