This is a lie. To presume you can and act upon that presumption is a travesty and does much damage to people's lives and spirits. This view is judgmental and prejudicial. Fat people suffer negative economic and social consequences due to the way they are treated in our society. Reputable medical, legal and lay people, after studying the facts, will state diets do NOT work, accept on a short term basis, and diets do much physical and psychological damage to everyone.
Medical people know diets for children are damaging and they still advocate diets.
If the medical and parental force upon a fat child does not damage them, their peers will, given the acknowledged acceptance of constant discrimination in school and play. Weight loss at any cost in today's social climate is dangerous and killing and perpetuates discrimination against fat people. The acceptability of fat prejudice and much of the hostility directed toward fat people is supported by the widespread belief that fat people can become thin forever. It is most important to teach children the love of movement and the enjoyment of activity. Weighing, charting, and comparing children by weight is NOT a benign procedure.