Considering that there is a direct link between children obesity, salt and a messy diet, there are only a few things there can be done with low costs and high efficiency in order to correct this sort of problems: get a healty diet (with less salt, more water and a moderate level of sugar - along with meat, vegetables and fruits) for your kid and put him to practice a sport.

We can not live a normal healty life without salt, it's a necessary ingredient in our daily diet. But, in the same time it is well known that a high salt intake is associated with blood pressure in the adult population.

There is an old saying (at least old for me) that says that a good leader always lead by example and not by force and/or coercion. Of course, you are not the ruler, god or emperor of your child, but he has something in common with any other people that follows you: the empathy. It is even more than empathy because the adults will always filter what they hear and see through reason and emotions

Reading some article about how to get children to be more sociable, especially the shy ones, I remembered the magical two words about a very good method the help them integrate into a collectivity: sports & team. All that articles I've read in the last hours where considering that the shy kid was the only child in the family and he was surrounded by adults, with other children somewhere in the background.