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Medical Aspects of Islamic Fasting

There are over 1.58 billion Muslims in the world. The majority of them observe total fasting (no food or water) between dawn and sunset during the month of Ramadan. They do so not to lose weight or for any medical benefit, but because it is ordained in the Quran which says, “O you who believe! Fasting is prescribed to you, as it was prescribed for those before you (i.e. Jews and Christians) so that you may (learn) self-restraine” (2:183).

Food is needed by the body to provide energy for immediate use. This is done by burning up carbohydrates, that is, sugar. Excess of carbohydrates which cannot be used are stored up as fat tissue in the muscles and as glycogen in the liver for future use. Insulin, a hormone from the pancreas, lowers blood sugar and diverts it to other forms of energy storage, that is, glycogen. To be effective, insulin has to be bound to binding sites called receptors. Obese people lack receptors. Therefore, they cannot utilize their insulin. This may lead to glucose intolerance.

When one fasts (or decreases carbohydrate intake drastically), it lowers one’s blood glucose and insulin level. This causes a breakdown of glycogen from the liver to provide glucose for energy needs and break-down of fat from adipose tissue to provide for energy needs. On the basis of human physiology described above, semi-starvation (ketogenic diets) have been devised for effective weight control. These diets provide a calculated amount of protein in divided doses with plenty of water, multivitamins, etc. These effectively lower weight and blood sugar, but because of their side effects, should be used only under the supervision of physicians.

Total fasting reduces or eliminates hunger and causes rapid weight loss. In 1975, Allan Cott in his Fasting as a Way of Life,noted, “Fasting brings a wholesome physiological rest for the digestive tract and central nervous system and normalizes metabolism.” It must be pointed out, however, that there are also many adverse effects of total fasting. That includes hypokalemia and cardiac arrhythmia associated with low calorie starvation diets used in unsupervised programs.


Dr. Soliman from University Hospital , Amman , Jordan has reported that during the month of Ramadan 1404 AH (June-July, 1984 AD) healthy Muslim volunteers@2 males and 26 females ranging in age from 15-64 and 16-28 years respectively-were studied. They were weighed and their blood levels of cortisol, testosterone, Na, K, urea, glucose, total cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), triglycerides (TG) and serum osmolality were measured at the beginning and at the end of Ramadan. There was significant loss of weight in males from a mean of 73.8 +/-6.2 kg to 72.0 +/-7.1 kg (P less than 0.01) and in females from 55.2 +/-4.8 to 54.6 +/-4.2 kg (P less than 0.05). Blood glucose levels rose in males from 77.7 +/-23.6 mg/dl to 90.2 +/31.2 mg/dl (P less than 0.05) and in females from 76.0 +/-7.6 mg/dl to 84.5 +/-11.1 mg/di (P less than 0.002). All other parameters did not show significant changes.

Dr. F. Azizi and his associates from the University of Medical Sciences , Tehran , Iran has reported the following. Serum levels of glucose, bilirubin, calcium, phosphorus, protein, albumin, FSH, LH, testosterone, prolactin, TSH, T4, T3, and T3 uptake, as well as prolactin and TSH responses to TRH were evaluated in a group of nine healthy men before and on the 10th, 20th, and 29th days of Ramadan. Mean body weight decreased from 65.4 +/- 9.1 to 61.6 +/- 9.0 kg at 29th day. Serum glucose decreased from 82 +/- 4 mg/dl on the 10th day, and increased thereafter (76 +/- 3 and 84 +/- 5 on the 20th and 29th days of fasting respectively). Serum bilirubin increased from 0.56 +/- 0.17 to 1 43 +/-.52 mg/dl on the 10th day, and decreased thereafter ( I. I. +/- 0.4 on the 20th and 29th days). All changes returned to basal values four weeks after fasting. There were no significant changes in serum levels of Ca, P. protein, albumin, and any of the measured hormones. Prolactin and TSH responses to TPH were also unaltered. He concluded that 1) intermittent abstinence from food and drink for 17 hours a day for 29 days does not alter male reproductive hormones, hypothalamic-pituitary- thyroid axis or peripheral metabolism of thyroid hormones and 2) physicians caring for Muslims should be aware of changes of glucose and bilirubin during Ramadan.

Therefore it is concluded from the above two studies that the pre- scribed fast does not cause any adverse medical effect and on the contrary, may have some beneficial effect on weight and lipid metabolism.


The prescribed fast of Muslims is different from the so-called “Diet Plans” because it has beneficial features of both plans. Its unique medical benefits are due to the following factors:

1. As compared to other diet plans, fasting in Ramadan does not cause malnutrition or inadequate calorie intake since there is no restriction on the type or amount of food intake before beginning the fast or upon ending the fast at sunset. This was confirmed by M.M. Hussaini in 1974, when he conducted dietary analysis of Muslim students at the University of North Dakota , State University at Fargo during Ramadan. He concluded that calorie intake of Muslim students during fasting was at two-thirds of NCR-RDA.

2. Fasting in Ramadan is voluntarily undertaken. It is not a prescribed imposition from a physician. In the hypothalamus part of the brain there is a center called “lipostat” which controls the body mass. When severe and rapid weight loss is achieved by starvation diet, the center does not recognize this as normal and, therefore, reprograms itself to cause weight gain rapidly once the person goes off the starvation diet. So the only effective way of losing weight is slow, self-controlled, and gradual weight loss which can be achieved by modifying our behavior and changing our attitude about eating especially by eliminating excess food. Ramadan is a month of self-regulation and self-training in terms of food intake thereby causing hopefully, a permanent change in lipostat reading.

3. With the prescribed fast, Muslims are not subjected to a diet of selective food only (i.e. protein only, fruits only etc.). An early breakfast, before dawn is taken and then at sunset the fast is broken with something sweet i.e. dates, fruits, juices to offset any hypoglycemia followed by a regular dinner later on.

4. Additional prayers are prescribed after dinner which help metabolize the food. Using a calorie counter, I counted the amount of calories burnt during the special night prayer of Ramadan (tarawih). It amounted to 200 calories. This form of prayer as well as the five daily prescribed prayers use all the muscles and joints and can be considered a mild form of exercise in terms of calorie output.

5. Ramadan fasting is actually an exercise in self discipline. For those who are chain smokers or who nibble food constantly, or drink coffee every hour, it is a good way to break the habit.

6. The psychological effect of Ramadan fasting are also well observed by the description of people who fast. They describe a feeling of inner peace and tranquility. The prophet advised those fasting, “If one slanders you or aggresses against you, tell him ‘I am fasting.”‘ Thus personal hostility during the month is minimal. The crime rate in Muslim countries falls during this month.

It is my experience that within the first few days of Ramadan, I begin to feel better even before losing a single pound. I work more and pray more. My physical stamina and mental alertness improve. As I have my own lab in the office, I usually check my chemistry, that is, blood glucose, cholesterol, and triglyceride before the commencement of Ramadan and at its end. I note marked improvement at the end. As I am not overweight, thank God, weight loss is minimal. The few pounds I lose, I regain soon after. Fasting in Ramadan will be a great blessing for the overweight whether with or without mild diabetes (Type 11). It benefits those also who are given to smoking or nibbling. They can rid themselves of these addictions in this month.


As mentioned earlier, the sick are exempt from fasting. But some, for whatever reasons, do decide to observe fasting. For physicians treating Muslim patients, the following guidelines are suggested.

Diabetic Patients: Diabetics who are controlled by diet alone can fast and hopefully, with weight reduction, their diabetes may even be cured or at least improved. Diabetics who are taking oral hypoglycemia agents like Orinase along with the diet should exercise extreme caution if they decide to fast. They should reduce their dose to one-third and take the drug not in the morning, but in the evening at the time of ending the fast. If they develop low blood sugar symptoms in the daytime, they should end the fast immediately. Diabetics taking insulin should not fast. If they do, at their own risk, they should do so under close supervision and make drastic changes in the insulin dose. For example, they should eliminate regular insulin altogether and take only NPH in divided doses after ending the fast or before the pre-fast breakfast. Diabetics, if they fast, should still take a diabetic diet during the pre-dawn meal, the ending of the fast meal, and dinner. The sweet snacks common in Ramadan are not good for their disease. They should check their blood sugar before breakfast and after ending their fast.

Hypertensive or Cardiac Patients: Those who have mild to moderate high blood pressure along with being overweight should be encouraged to fast, since fasting may help to lower their blood pressure. They should see their physician to adjust medication. For example, the dose of water pill (diuretic) should be reduced to avoid dehydration, and long acting agents like Inderal LA or Tenormin can be given once a day before the pre-dawn meal. Those with severe hypertension or heart diseases should not fast at all.

Migraine Headache: Even in tension headache, dehydration or low blood sugar will aggravate the symptoms, but in migraine during fasting, there is an increase in blood free fatty acids which will directly affect the severity or precipitation of migraine through release of catecholamine. Patients with migraines are advised not to fast.

Pregnant Women (normal pregnancy): This is not an easy situation. Pregnancy is not a medical illness. Therefore, the same exemption does not apply. There is no mention of such exemption in the Quran. However, the Prophet said that pregnant and nursing women do not have to fast. This is in line with God not wanting anyone, even a small fetus, to suffer. There is no way of knowing the damage to the unborn child until delivery, and that might be too late. In my humble opinion, during the first and third trimester (three months) women should not fast. If however, Ramadan happens to come during the second trimester (4th-6th months) of pregnancy, a women may elect to fast provided that 1) her own health is good, and 2) it is done with the pen-nission of her obstetrician and under close supervision. The possible damage to the fetus may not be from malnutrition provided the Iftaar and Sahoor are adequate, but from dehydration, from prolonged (10-14 hours) abstinence of water. Therefore it is recommended that Muslim patients, if they do fast, do so under medical supervision.

By Shahid Athar , M. D.



1. Bistrian,B.R.,”Semi-starvation Diet Recent Development”, Diabetic Care, November 1978.

2. Blackbum, G.L., et el, “Metabolic Changes On PSMF diet” diabetes, June 1976.

3. Cott, A., “Fasting Is A Way Of Life”, New York: Bantam Books, 1977.

4. Hirsch, Jules, “Hypothalmic Control Of Appetite” Hospital Practices, February 1984.

5. Khurane, R.C., “Modified Ketogenic Diet For Obesity” , Cancer Monthly Digest, July 1973.

6. Hussaini, N.M., Joumal of Islamic Medical Association, October 1982.

7. Athar, S., “Therapeutic Benefits Of Ramadan Fasting “, Islamic Horizon May 1984.

8. Soliman, N., “Effects Of Fasting During Ramadan”, Journal of Islamic Medical Association, November 1987.

9. F. Azizi et el, “Evaluation of Certain Hormones And Blood Constituents During Islamic Fasting Month”, Journal of Islamic Medical Association, Nov. 1987.

10. Athar, S., “Fasting For Medical Patients – Suggested Guide-line” Islainic Horizon, May 1985.

Soliman, N. “Effects Of Fasting During Ramadan,” Journal of the Islamic Medical Association, November 1987.

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