@olivewreath13 Whilst I feel for you, I feel for your child. I was a fat child, and today some people would be saying I didn't eat healthily. Except my mother was a nurse and a health visitor and we cooked from scratch every night, rarely had fried anything. It turns out I have lipoedema, a fat disorder that has a connective tissue element. It gives you a certain shape, and sufferers post photos of themselves as "fat" children. Except lipoedema isn't normal fat. The cells multiply rapidly and get much larger than undiseased fat. That and a thyroid autoimmune disorder meant I spent thirty years under the impression that my large body was somehow my fault, that I could somehow control it. This was not true.
Fat acceptance and body neutrality are the way to go. If you aren't going to embrace calorie counting combined with a good quality heart rate tracker then anyone who is not "normal" is just going to be hurt and discouraged. Children should not diet in my opinion. They do not have enough control over their food. That doesn't mean that they shouldn't have basic knowledge on how many calories their body needs to maintain their weight, what that means practically for meal calorie count. If there is any kind of hormonal disorder then natural appetite suppressant doesn't work. I have had leptin resistance as well, I never felt satiated until I went through that. Thyroid hormones have a massive effect on appetite.
My attitude is that you only have one body, you need to love it the way it is because you don't get another one, you need to know what healthy is and you also need to know what narrow beauty standards are because you will never fit them. Let's face it, a lot of the fat hatred is nothing about health, it's about women's perceived lack of compliance. How can you explain "fat" without reference to all this? It's only part of the picture.
My child is being taught to eat well, move lots and work at sports and skills. Physical health is how she feels and what the metrics say, not what a random person perceives.