Believe it or not, eating more frequently during the day actually stimulates the metabolism. The process of breaking down and absorbing food uses calories, so eating more actually helps us burn more calories per day. On a 2000 calorie per day meal plan then, you'll lose more weight eating five 400 calorie meals daily than two 1000 calorie meals.
In addition, your metabolism is the most rapid in the morning; coming off the overnight fast, your liver and muscles require replenishment of their energy stores, so ingested calories are deposited as useful short term energy forms. Later in the day, when these stores are repleted, excess calories are deposited into your long term energy repository, i.e. the fat stores. Therefore, we should ingest our largest meals earlier in the day - large breakfast, modest lunch, smaller dinner.
Fine tuning your meal planning in this way will recharge your weight loss efforts.