Penitence, purification, mourning, sacrifice and enhancement of knowledge and powers were some of the aims of fasting envisaged by these religions. Even philosophers, scientists and physicians of the past adopted fasting as a healing process needed to recreate health where there was sickness. Socrates, Plato, Aristotle, Galen, Paracelsus, and Hippocrates all believed in fasting as a form of therapy. We find in scriptures such as the Bible, for example, prophets like Moses, Elijah, Daniel and Jesus resorting to fasting for the sake of spiritual purification as a means of communication with God. The Quran also indicates that fasting is a religious practice common to the religions of the past:

O ye who believe! Fasting is prescribed to you as it was prescribed to those before you, that ye may (learn) self-restraint, - (Quran 2:183)

Ramadan fast is one pillar of Islam. During one moon-month believers don’t eat and drink from sunrise till sunset. Sexual contact is also prohibited daytime. These are the physical signs of fast. However, the deeper meaning is more important. We know since Adam that humans have instincts like animals. The more we can restrain the function of our instincts over us the more we are mind and heart operated beings. In Ramadan our heart opens for the words of Allah. Our thoughts are more profound and our conduct is more kind. This is the month of forgiveness and good deeds. Also, Ramadan helps to understand for rich the life of those who live in poverty and suffer of shortage of food and livelihood during the whole year. This is the month of purification. Physically our body gets rid of those toxins and waste which can only leave by fasting. Spiritually our heart gets rid of thought and side-feelings which polluted our thinking and behavior.
However, Ramadan fast cannot be a torture. Who is sick or is on the way has excuse to suspend fast and these days can be made up later. Who suffers of a permanent reason what unables him to perform fast he can give ransom for poor and make good deeds as offering. Fast is for us and not against us. It builds our physical and spiritual character. Fast was prescribed in every religion. It is not a unique Islamic regulation. However, religions have changed and Islam remained the same.

Now let us review the fasting traditions of Judaism, Christianity, and Hinduism.

Judaism

The Jewish calendar contains comparatively few regular fast-days. Yom Kippur (the Day of Atonement), is the only fast-day prescribed by the Mosaic Law:And this shall be a statute forever unto you: that in the seventh month, on the tenth day of the month, ye shall afflict your souls, and do no work at all, whether it be one of your own country, or a stranger that sojourneth among you: For on that day shall the priest make an atonement for you, to cleanse you, that ye may be clean from all your sins before the LORD. It shall be a sabbath of rest unto you, and ye shall afflict your souls, by a statute forever (Leviticus 16:29-31).
The Jews observe ten days of repentance starting with Rosh Hashanah (the Jewish New Year) and ending with Yom Kippur (the Day of Atonement). This is a time to consider the sins of the previous year and repent.

Yom Kippur is the day on which Jews believe that the fates of all Jews are to be sealed for the coming year. This day is held to be the most solemn and serious day in the Jewish calendar, which involves grieving for sins committed in the past year as well as praying for forgiveness. On this day, Jews fast for 25 hours from sundown on the previous evening until sundown the next night. To the Jews, fasting is more than just refraining from drinking and eating: working on fast days is not permitted, and having sexual relations and bathing, as well as using ointments and leather shoes, are prohibited. The fast begins with a special evening service known as Kol Nidre (All Vows), and synagogue services last for the whole of the following day until the fast ends.
It is also customary among many Jewish communities to fast on the eve of New Year’s Day: Rosh Hashanah.
Besides Yom Kippur, there were four regular fast-days established by Jewish tradition to keep the memory of various sad events that affected the Jewish nation during their captivity. According to some scholars of the Talmud these fasts were obligatory only when the nation was under oppression, but not when there was peace for Israel.
The Synagogue is also empowered to impose fasting in case of a misfortune befalling the people, such as pestilence, famine, or an evil decree enforced by the ruler of the day.The Jewish fasts normally begin at sunrise and end with the appearance of the first stars of the evening, (with the exception of Yom Kippur, which lasts from sundown to sundown). The giving of charity on a fast-day, specially the distribution of food necessary for the evening meal, is encouraged (Jewish Encyclopedia).

Christianity

From the sermon on the Mount, we know that Jesus instructed his earliest disciples to fast: When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show men they are fasting. I tell you the truth, they have received their reward in full. But when you fast, put oil on your head and wash your face, so that it will not be obvious to men that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you (Matthew 6:16).

It is obvious that the kind of fast prescribed by Jesus was already familiar to the Jewish community, as there is no record that he taught any change. Therefore, it must have been complete abstinence from food and drink, as the above verses indicate. That is why he spoke of putting oil on the head and washing the face so that the tiredness of fasting may not be obvious to others.

Today, many Christians following the guidelines of the Church do not practice this kind of fasting; they avoid eating meat for a few days; or in some cases eat only one meal a day during the fast. And there is no ban on drinks either. This may be because the New Testament does not give any details as to how to fast.

Lent, which is observed by Roman Catholic, Anglican, and certain other churches, is a forty-day period of fasting and penitence in emulation of Jesus Christ’s example in his fast in the wilderness (deserts) of Judea.

The first main component of Lent is the obligation of abstinence which applies to all older than 14. For Roman Catholics, abstinence means not eating meat in any form, but not including fish. But there is also a concept of “partial abstinence”, meaning eating meat only once per day.

On three occasions in the Bible, people fasted for forty days. The first occasion was when Moses received the Ten Commandments (Exodus 34:28). The next occasion was when Elijah encountered God before the anointing of Elisha (I Kings 19:8). The third occasion for such a fast was when Jesus was in the wilderness and tempted by Satan (Matthew 4:2).

There are many reasons given in the Bible for fasting. It is seen as an act of sacrifice that reminds Christians of God and through fasting, while the flesh is denied comfort, the spirit is strengthened.

Hinduism

Fasting in Hinduism is the denial of the physical needs of the body for the sake of spiritual gains. According to Hindu scriptures, fasting helps create an attunement with the Absolute by establishing a harmonious relationship between the body and the soul. Hindus believe that this counter the tendency of people to be obsessed with worldly indulgences, and not allowing time for spiritual attainment. Worshippers are advised to impose restraints on themselves to get their mind properly focused. One form of this restraint is fasting.Fasting is prescribed on all Ekadasi days. Ekadasi is a Sanskrit word that refers to the 11th day of the lunar fortnight, twice a month (Bowker, 173).
Vedic scriptures strongly recommend observing a complete fast on the day of Ekadasi (without drinking water). Everyone from the age of eight to eighty, irrespective of caste, gender, or any material consideration, is recommended to fast on this day to make spiritual progress.
Those who cannot perform the austerity of complete fasting, can follow Ekadasi by eating once a day at midday, or eating once a day in the evening. However, under no conditions should one eat grains in any form on this day. On this day, devotees fast
On this day, devotees fast during the day and keep vigil during the night in prayer and meditation.
Observing Ekadasi, it is believed, would destroy all sins and purify the mind.
Fasting is seen not only as a part of worship; it is also a training of the mind and the body to endure all hardships and to persevere under difficulties and not give up.