when you stomach is full, you can not stop your mind thinking about other things such as money, love, sex, entertainment, etc, especially when you are alone at night.
When your stomach is empty, your mind will not disperse, and you can concentrate more on the teaching of buddha.

As for the reason above, monks will not allowed to have dinner.

That's my grand father told me long long time ago

In the past, if monk have dinner so lady can serve dinner for monk at night time maybe some ladies and monks make someting outrules , at night time difficult to control monk behaviour especially when monk and ladies see together out of sight  . To protect wrong thing may happen with monk so buddha make a rule not allow monk have dinner.
  The last I think have 2 meals per day make good health because dinner make a bad health (fat & weight)   

The 6th precept:

6. Vikalabhojana veramani sikkhapadam samadiyami

I undertake the precept to refrain from eating at the forbidden time (i.e., after noon).

Rationale:
...aims at cutting down the sloth which is experienced after a day's work and a substantial evening meal, while it ensures that the body is light and fit for meditative practice.
(source: http://www.accesstoinsight.org/lib/authors/khantipalo/wheel206.html#atthasila)

After 12 noon, we do not consume any food.At most we drink a little bit of a beverage.This is enough.For what reason?Because it is considered that 2 meals daily are enough for us to live.As for the third meal, if we chant, pray, maintain the precepts, and meditate, we do not use much energy.So 2 meals are enough.
(source: http://www.dmc.tv/pages/en/good_questions_good_answers/sila_vata.html)

        Where are MONKS came from ?
         Where is BUDDHA came from ?

          How about CHINESE BUDDHA ?
          How about VIETNAMESE BUDDHA ? 
          How about BUDDHA  around the world ?

            Why they are difference ?, Monks are the HUMAN,
          What is Big Deal about dinner. Think about !!!!!!!!!!  

          Howmany RELEGION in this Wolrd ? They are all Good.
          Which one BETTER ? I don't know.


           Plese give me good answer.

                 Oooh I am lao in USA.

Seems like you dudes have never been a monk before.

The reason why monks don't eat after lunch is actually quite simple, it is to feel hunger, and hence, feel the dependecy that humans have by being alive. We are not independent, no self, we are conditioned beings. When the Buddha was still practising before enlightenment, he followed some other teachers who practised fasting, not eating for days at a time. He later abandoned this practise since he realized that the body needed nutrients to keep the mind functioning properly in order to gain wisdom. This also lead to the "middle path" which translates to living in moderation and not extremes. This hunger or craving/wanting is the root of suffering/life, if we monks are reminded of this hunger everyday, we will be able to understand it and fight it head on, thus becoming free from it eventually.

why do you call yourself as khonthakek, i don't understand,,