Adopted children and food obsession?

One idea that helped out my co-worker who is also a speech and language therapist....and something I'm keeping in the back of my mind for possible use is a food chart/step.... the hardest part is setting it up....think of all the foods you feed the kids and take pictures of them. then every night put a sheet ordered with 1, 2, 3... (i usually do this with velcro when working with my kids at my work with other needs, but the chart/picture/visual board idea is the same) then introduce them their foods that will be served that night (e.g. maccaroni and cheese, apple slices, breadsticks, peas, yogurt etc.) explain, these are our food items and then let them velcro out what they want to eat first. When they are done with that item they take off the picture and go to the 2nd item...and so forth until they visually see what they have eaten. For my co-worker...it worked because her daughter saw that there was food and she could visually see how much she ate... of course this was a preschooler hence the picture ideas. Forgive me,I don't remember the ages of your kids.