This tragic state of affairs obtains because members of the public continue to receive the wrong information and advice about obesity, and in particular, about child obesity.
When children become fat it is essentially because they are eating salty food. Children are especially vulnerable to salt because of their small size and small blood volume, and because their blood vessels are weaker than those of adults. Salt, and the water it attracts to it, can more easily distend weak blood vessels than fully mature ones. The resulting increase in blood volume and other fluid retention results in weight gain, as well as higher blood pressure and many other undesirable consequences. The smaller the child, the less salt they should have - and a baby, of course, should have no salt at all. - Babies can die if they are fed salty food.
Because children have much smaller bodies than adults it would be best if they had no more than half as much salt as adults. Most children, however, have much more than this because they eat so many snacks and instant foods. Just one cheeseburger, for instance, contains almost double the recommended daily salt maximum for children. There are high amounts of salt in packet soups, instant noodles, ketchup and sauces, sausages, burgers and savoury snacks. Fat children will lose weight fast if they eat less salt. And even faster still if they eat plenty of fresh fruit and unsalted vegetables, because these are rich in potassium, which helps to displace sodium from the body. Overweight children should not be put on a diet; dieting is harmful and unnecessary and does not usually result in weight loss. Once children start dieting it is often the beginning of a lifetime of yo-yo dieting and increasing weight and ill-health.
Unfortunately bread contains a lot of salt and most families eat quite a lot of bread because of using it for sandwiches in packed lunches, and for toast, etc. Because of its high salt content bread is not a healthy food for little children or for anyone who is overweight. Some bread manufacturers have lowered the salt content of certain loaves, but most bread still usually contains 0.5g or more of sodium per 100g. This is too much. - Always check on the packet; look for the lowest sodium content.
Cheese is often recommended as being good for children because it contains calcium, but cheese is not really good for children because it has a high salt content. So don't give them a lot of it. Children can get plenty of calcium by drinking milk and by eating yogurt (but avoid the sort of yogurt that has lots of chemical additives).
And see Sodium in foods
Read my Mensa article on Obesity and the Salt Connection