Dear noble brothers, the Prophet PBUH used to break his fasting on three dates, then he offers Maghrib, and after that he eats. 

The unbelievable thing is that the sugar in dates is the fastest kind of sugar to reach blood from the mouth, for it takes only 10 minutes, so by eating three dates, the sugar reaches the satiety center in the brain. 
 

By eating three dates, then offering Maghrib Salah, 10 minutes will pass, and you will feel satiation, which makes you eat moderately afterwards. Well, when does man feel satiation? He does so in two situations: the first situation (which is the worse) is when his stomach is full,

and the second one is when his satiety center in the brain is stimulated.

Hence, starting your Iftar (breaking your fasting) with three dates will stimulate the satiety center in the brain,

and so you will eat moderately as if you are having any other meal during the day in other months.