The fastest way to loose weight is not recommended, that is starving yourself and dehydrating yourself by the use of diuretic foods or pills. Most popular Fad diets work this way, by cutting out whole food groups causing severe calorie deficit while eating foods that have a diuretic effect. This will loose weight fast but it is muscle and water that is being lost and very little fat.
The healthy alternative is to eat a balanced diet of carbohydrates, protein, and esential fats while cutting portion sizes. Removing whole food groups and meal replacements may be fast but will not give your body all the required nutrients and cause other health problems. Exercise will increase your calorie deficit without the need to starve. Cardio exerecise should be done for heart and lung health but weight training should be done also to maintain lean muscle which is needed to maintain a healthy metabolism and to force the body to burn fat and not muscle.

