The fastest way to lose excess weight is to cut down on salt/sodium. This reduces water weight/fluid retention.
Other tips include 1) increasing calcium intake, which reduces fluid retention AND fat retention and 2) lowering carbs and increasing intake of healthy saturated fats.
3) Avoid prescribed pharmaceutical drugs as far as you can because they are a major, and increasing, cause of fluid retention/salt sensitivity. See weight gain from amitriptyline and other antidepressants and also weight gain from prescribed steroids, HRT and other prescription drugs.
4) Cut down on bread and processed food. Cook fresh foods instead.
5) Avoid artifical sweeteners, including aspartame, saccharine, sucralose, diet drinks and low calorie drinks.