Always remember this simple truth, if you want to lose weight you will need to expend more calories than you consume. The main points of most weight loss diets are based on this rule. If you reduce your daily caloric intake by 600 during the course of a month you can lose between 2-6 kilos (5-12 pounds).
If you reduce daily calories by 800 during the first month you can lose between 10-20 kilo (20-40 pounds). The greater your original weight the more weight you will lose. However, the more calories you reduce the harder dieting will be for you.