It depends. Sometimes a change in diet, even to what seem to be healthy foods, can be an indicator of disordered eating, but it isn’t always. For instance, a child who suddenly declares s/he is Vegan could just be using that as an excuse to explain away what is really happening, which may be that she is engaging in unhealthy calorie restriction. With a closer look, you may notice that your child is restricting the healthy foods she eats and really not getting the well-rounded nutrients s/he needs for healthy body growth and maintenance.