Many weight loss doctors will tell you to never let yourself get hungry. Eat up to 6 times a day, but very small portions and very low fat/low carbohydrate. Those are the two main sources of weight gaining calories.
to answer your question, studies have shown that eating several meals a day (6-7 small meals) compared to three-four (moderately sized meals) has little affect on weight loss in general. Just keep it simple and eat the appropriate amount every day. Personally, i like to just eat when I'm hungry and stop and the right time. Sometimes I'll stop when I've had just enough to get by, and I always stop when I feel full. Think about it. If you're not sure how much to eat, it a medium amount and if you need more later you're body will tell you.