Fluid retention is the pre-eminent cause of obesity, and the main cause of fluid retention is salt sensitivity. In children a high salt intake causes salt sensitivity/fluid retention/obesity. In adults it is sometimes the result of eating salt and salty food during pregnancy, when altered hormone levels make the body vulnerable to salt. It is most dramatically and tragically caused by the taking of injudiciously prescription drugs such as steroids, HRT and certain tricyclic antidepressants.
The way to reduce obesity is to abandon the dieting fallacy and address the fluid retention by severely cutting down on salt/sodium intake and eating plenty of fruit and fresh vegetables as these help to remove from the body some of the excess sodium and its accompanying water.
You can lose weight by eating less salt! – Go on! – Try it!