If we're starting to work towards healthier food consumption, the place I like to start is the sugary beverages. So if they're having Frappuccinos, finding an alternative drink they enjoy that doesn't have the load of sugar that those have. Reducing juice and pop.
After that, we start getting into trying to find higher fibre grains that they might enjoy. This may be just by mixing grains. So not only whole wheat pasta, but mixing white and whole wheat pasta together so you're increasing your fibre slowly.