The best way to lose weight after you have your band surgery is to eat a meal that will eventually be the maximum amount of food that will fill you once your band is completely adjusted.  I tell my patients that it is better to fill your band into your diet rather than eat into your band fills.  If you watch what you eat during the period of band fills you will lose more weight and not have as many episodes of vomiting or feeling nauseous. 
Normally about 3-4 oz of your protein and 4 oz of vegetables will fill you once your band is adjusted properly.