Lots of people prefer eating smaller servings more frequently, some people need a snack to get through the day. Yet others have varying schedules that cause may fall between meals in a way that makes them hungry.
On the side bar there's a bunch more.
http://www.webmd.com/diet/obesity/features/6_meals_a_day#1 http://www.dailymail.co.uk/health/article-53111/Why-eating-l...