ABSTAINING FROM OVEREATING
God says in Qur’an:
“…and eat and drink, but do not transcend the limit[s]; indeed He does not like those who transcend the limit[s]. 
O friend, know that overeating undoubtedly kills the heart and makes the soul disobedient and oppressive; and know that hunger is the most exalted trait of a believer.
How beautifully has Yahya bin Ma‘aadh expressed [this reality]:
“If you make the angels of the seven heavens, the 124,000 prophets and their successors, and all the Divine scriptures, as your mediators, to enable your self to accompany you in detaching from the world and submitting to the Divine law, it [i.e. your self] would not agree. However if you were to take hunger as your mediator, and enter from the path of hunger, it would comply and obey you.” 
Hadhrat Imam al-Sadiq (‘a) in this connection says:
The stomach, due to overeating, transgresses, and the best state of a servant in the presence of God is when his stomach is empty of food, and the worst state of a human being before God is when his stomach is full. 
Narration of Presence
7. Evil effects of Overeating
Hadhrat Ustaad (perpetual be his esteem ) would say: fitna (sharpness of mind) does not merge with bitna (overeating and gluttony) . One who overeats is loquacious and speaks in confusion. And he (Ayatullah) writes in his book Sad Kalime (One Hundred Words): One who intelligently deals with his material food, must know that bitna (gluttony) is the opposite of fitna (perspicacity) and brings about increased stupidity and fitna (sedition). 
8. Overeating is a Hurdle in Spiritual Wayfaring to Allah
Akhund Mulla Husayn Quli Hamadani (may his spirit be sanctified) is one of the exalted saints and among the well-known students of Sayyid ‘Ali Shushtari (may his spirit be sanctified). He is also known as the greatest master of ethics and gnosis (‘irfan) in the later centuries. The spiritually united mystic, Marhum Maliki Tabrizi (may his spirit be sanctified) says about him: I have not seen a man of his caliber in the aforesaid things (i.e. long prostrations, worship, etc.). In one of his meaningful and invaluable instructions to Marhum Sayyid ‘Ali Agha Irawani (may his spirit be sanctified), Mulla Husayn Quli Hamadani writes as follows:
Janabe Agha! (O Mr.!) Take caution and beware of four impediments (of the spiritual path): Overindulgence in speech, overindulgence in food, overindulgence in sleep, and overindulgence in sitting with people; and on you is to transform and change that with the remembrance of Allah, the All-knowing King during the nights and days.
9. An advise from Iblis [Satan]
Imam al-Sadiq (‘a) narrated the following for Hafs bin Ghiyaath:
One day Iblis appeared before Hadhrat Yahya (‘a) in the state of having so many ropes hung around his neck.
Hadhrat Yahya (‘a) asked him: What are these ropes?
Iblis said: these are the selfish desires and needs of the children of Adam with which I [entrap and] trouble them.
Hadhrat Yahya (‘a) said: Is there any rope for me too?
Iblis said: Sometimes you have overeaten, and I have made you oblivious of prayer and the remembrance of God.
Hadhrat Yahya (‘a) said: I swear by God that henceforth I will never fill my stomach with food.
Iblis said: I swear by God that I likewise henceforth shall never advise any believer or monotheist. 
 Holy Qur’an, Surat al-A’raaf (7), v. 31
 Abu Taalib al-Makki, Qut al-Quloob, Egyptian ed., p. 215
 ’Allama Majlisi, Bihaar al-Anwaar, v.66, p. 336
 Perspicacity does not merge with gluttony. A human being who overeats would not be clever, and this statement of Hadhrat Ustaad (perpetual be his esteem) is an inspiration from the tradition of Hadhrat Amir al-Mu’minin (‘a) which says, “La tajtami’ al-fitnatu wal bitnatu” (The sharpness of mind cannot come together with overeating) (Haaji Noori, Mustadrak al-Wasaa’il, v.3, p. 81)
 Ayatullah Hasan Zahed Amoli, Sad Kalime, word no. 78, p. 37
 Ridha Mukhtari, Simaye Farzanegaan, pp. 59-60
 ‘Allama Majlisi, Bihaar al-Anwaar, v.63, p. 216
To be continued soon Insha Allah...