Imam As-Suyooti has reported that Al-Harith Ibn Kalda stated that: "Imposing abstinence from food" was the essence of medicine. Fasting, in medical terms, may mean a variety of things.

　　Research has shown that fasting can improve the control of diabetes. Another study has shown that fasting improved the health of persons with irritable bowel syndrome and constipation. Another study suggests that fasting may improve cholesterol levels.

　　Al-Bukhari has also reported that the Prophet narrated that Allah the Almighty Said: "The fast is for Me and I will give the reward for it, as he (who observes the fast) leaves his (sexual) desire, food and drink for My Sake. Fasting is a shield (from Hell) and there are two pleasures for a fasting person, one at the time of breaking his fast and the other at the time when he will meet his Lord. The smell of the mouth of a fasting person is better in Allah's Sight than the smell of musk."

　　i) 'Eed Al-Fitr: The day of festival after the Ramadan fasting

　　ii) 'Eed Al-Adh-ha: The 'Festival of Sacrifice' celebrating on the 10th of Dhul-Hijjah, the last month of Islamic Calendar

　　iii) Days of Jumu'ah (Fridays): If a person needs to fast on the day of Jumu'ah, either he should fast on the prior day of Jumu'ah and continue on the day of Jumu'ah, or he can fast on the day of Jumu'ah but has to continue the fast on the next day too.

　　Married women are admonished not to fast without the permission of their husbands (especially optional fasts), as the husband have a righty over their wives.

　　Sunnah and the narration reported by Imam Abu Dawood : "When one of you is fasting, he should break his fast with dates, but if he cannot get any, then (he should break his fast) with water, for water is purifying." Imam Muslim has reported that the Prophet said: "The Ajwah date is an excellent remedy." The best days for fasting are Mondays and Thursdays. Imam At-Tirmithi also reported that the Prophet said: "The deeds of men are presented to Allah on Mondays and Thursdays, and I like mine to be presented when I am fast­ing." The Ayyam Al-Beedh (the thirteenth, fourteenth, and fif­teenth of each lunar month) are also recommended for fasting.