Snack all the time
An idea that has worked for people is to plan in advance what foods and what quantities you'll be eating for the day.
Then, decide to stick with this plan. If possible, place all these foods in one container and snack on it all you want. But, when it's gone you're finished for the day (as you planned it). Some people divide the day's food into 5-6 parts, eating one portion every few hours.