Fasting during Ramadan is a religious duty for all healthy adult Muslims. Ramadan is the ninth month of the Islamic lunar calendar. Many of the world's great religions recommend a period of fasting or abstinence. The Islamic fast during the month of Ramadan during which a whole month is dedicated to fasting is particular to Islam, and is strictly observed by millions of Muslims worldwide. Since more than a billion people worldwide follow Islam, it is assumed that hundreds of millions of people observe the Ramadan fasting each year. The experience of fasting teaches Muslims self-discipline and self-restraint, and reminds them of the feelings of the impoverished. Fasting is not obligatory for children. Menstruating women as well as sick and travelling people are excused, and pregnant and lactating women are permitted to postpone the fasting during Ramadan, however, they should fast during another month of the year, when they have no reason for exemption. 1,2 During Ramadan, the majority of Muslims have two good-sized meals; one immediately after sunset and the other just before dawn. They are allowed to eat and drink between sunset and dawn but not after dawn. Since the Islamic calendar derives from a lunar cycle, the Islamic year contains 354 days. Therefore, the Ramadan month occurs 11 days earlier every year, and may occur in any of the four seasons, making the length of fasting hours variable from 11 to 18 hours in tropical countries. The month of Ramadan is either 29 or 30 days.From the physiological standpoint, Islamic fasting provides a unique model of fasting. It is distinct from regular voluntary or experimental fasting by the fact that the observant of the fast does not drink during fasting hours. In addition, Ramadan fasting is not just disciplining the body to restrain from eating and drinking. The eyes, ears, tongue, and indeed the whole body, are equally obligated to be restrained. Therefore, one may assume that physiological changes occurring during Islamic fasting would be different from those noted during an experimental fast. This review discusses the findings of research conducted on various aspects of Ramadan fasting and its impact on some disease processes. A comparison with the effects of experimental fasting is attempted whenever possible. The author conducted a Medline search, reviewed local journals in some of the Islamic countries, as well as some research findings from two international congresses on health and Ramadan.
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Impact of Ramadan Fasting on Metabolism
Carbohydrate MetabolismThe effects of experimental short-term fasting on carbohydrate metabolism have been reviewed extensively.
5,6The post-absorptive period of fasting is defined as 8 to 16 hours after eating, a period of very early adaptation to starvation. The primary metabolic priority of this period is the provision of adequate glucose for the cells of the brain, red blood cells, peripheral nerves and renal medulla. A slight decrease in serum glucose to around 3.3-3.9 mmol/L (60-70 mg/dL) occurs a few hours after fasting i...