Let me start with this: lots of kids from chaotic homes have a history of inconsistent eating. Parents who are failing to properly care for their children are typically not feeding them properly. As a result, many if not most of the kids who come into foster care have issues with food.
I love food. I love to cook it. I love to eat it. I love to share it. I love to talk about it. Food is important in my life, and so food is important in my home.
Early in our foster parenting journey, someone shared with me the book Love Me, Feed Me. It was one of only two books I read during the first 6 months of our first foster placement (the other being a brainless chick-lit novel I despised but read while sitting on the floor of the foster kids' room every night so they wouldn't cry themselves to sleep). I cannot recommend Love Me, Feed Me enough.
The premise is based on Ellyn Satter's work, and it's pretty simple: the adults' job is to teach kids to be competent eaters. Competent eaters feel good about eating, eat consistently, and enjoy food. Competent eaters trust themselves to eat well. This means they can eat a wide variety of foods, try new foods, choose foods that support their physical health, eat enough to satisfy their hunger, and stop eating when they are full.
Teaching competent eating is done through structure and modeling, not through coercion or pressure. It's not the adults' job to make kids do anything or to get kids to do anything. It's simply the adults' job to set up the structure that will, over time, teach kids what competent eating looks like and how to eat competently.
That simple premise, then, gets implemented through the division of responsibility (DOR): Adults choose what foods are offered, when they are offered, and where they are offered. Kids choose if, what, and how much they will eat from the offered foods. The DOR means you can parent all of your kids the same way, because the rules are the same for the adopted and biological kids, the "too fat" and "too thin" kids, or the typically- and differently-abled kids. The DOR also means meals can be relaxed and pleasant opportunities to connect, because the adult has finished all of his/her part of the responsibilities BEFORE sitting down at the table.
The book delves into the details of how to implement the DOR, potential roadblocks, typical eating problems with foster/adoptive kids, and a host of other topics. There's a ton of valuable information. Suffice to say, though, that it revolutionized how I thought about feeding my children, particularly the non-biological kids. With that revolution in thinking came a tremendous sense of relief and an immediate increase in the joy of preparing and eating meals in my house.