Fat is not something you have, it is something you are. We identify with our bodies. So the child gets the message that this fatness is badness. Emphasize body trust. Bodies say when they're hungry.
People come in all different weights and heights.
You and your body are unique in all the world. Accept that weight may not change even when there is progress in self-care. Higher weight is correlated with health problems, especially in later life. Because we have no treatments, preventing weight problems is preferable, which means all kids need to hear the message. Care about how they are doing, not what they weigh, and develop a relationship that communicates this to them.