Why you can't believe the studies on fasting during Ramadhan

Fasting during the month of Ramadhan not only refers to the restriction of food and beverages between the hours of sunrise and sunset, but also to the restriction of other appetites, such as sexual abstinence and refraining from negative behaviour such as swearing and lying.

Various researchers have studied fasting at Ramadhan, and generally found that while the body does face challenges during the month, things go back to normal after Ramadhan is over:

Sports

A study in 2009 on middle distance runners established that nightly sleeping time and energy intake were lower on day 21 of Ramadhan than before fasting began. Fatigue had also increased by the end of the month. The researchers noted that metabolic, hormonal, and inflammatory measurements rose over the month, but had gone back to pre-Ramadhan levels seven days after fasting had been completed.

Another 2009 study on elite judokas also noted a rise in fatigue but also 'little effect' on aerobic performance and on very short duration sprinting and jumping test performance, and concluded that experienced athletes can maintain both sufficient energy intake and normal training loads during Ramadhan.

Aerobic exercise

This 2012 study systematically studied what happens to various components of blood and urine for a group of fasting men while they exercised, compared to a control group who had eaten. While there were changes for fasting the authors said that aerobic training in a fasted state lowers body weight and body fat percentages, whereas 'fed' aerobic training only decreases only body weight.

Physical work

Fasting labourers studied in Germany in a 1991 study were found to suffer the symptoms of 'moderate to severe' dehydration, from tachycardia (rapid heartbeat), severe headaches, dizziness, nausea, vomiting and circulatory collapse (low blood pressure, cold extremities). Ramadhan 1990 and 1991 occurred around March, when it would presumably have been fairly cool weather. Sunrise to sunset would have been about 12 hours, according to calculations from Chennai IQ.

Pregnancy

A 2008 study in the Journal of Obstetrics and Gynaecology Research has found that fasting during Ramadhan does not have adverse effects on intrauterine fetal development or the fetus' health. The researchers studied 36 healthy ladies who had uncomplicated pregnancies of at least 20 weeks' gestation and compared them to a control group of pregnant ladies who were not fasting. The study found that fasting of a mean of 18 days did not affect the babies' growth, though the fasting ladies had lower blood glucose levels. It is not clear whether results would be different if the ladies had actually completed the entire month of fasting, which would last 29 or 30 days.

Chronic kidney disease

A 2007 study from the Saudi Journal of Kidney Diseases and Transplantation studied 15 patients with chronic kidney disease (CKD) who did not yet require dialysis against healthy counterparts both before Ramadhan and after it. Researchers established that N-acetyl-beta-D-glucosaminidase (NAG) levels rose for the fasting CKD patients, indicating kidney damage.

Diabetes type I and II

Suggested insulin regimens are provided in this 2008 study for those with well-controlled diabetes type I. Even then, frequent testing is suggested to determine if blood glucose is too high or too low for fasting to continue.

Another 2010 study showed that providing some training on physical activity, meal planning, glucose monitoring, hypoglycaemia (low blood sugar), dosage and timing of medications to people with diabetes type II can have a beneficial effect. Researchers divided the diabetes patients into two groups, those, who had received the training and those which had not. There was an average weight loss of 0.7 kg after Ramadhan in the trained group, whereas the untrained group gained an average of 0.6 kg. There were also more hypoglycaemic events in the untrained group.

Weight gain is common enough. Two-thirds of a population of Saudi families in Jeddah (59.5%) surveyed reported weight gains after Ramadhan in 2011, attributing it variously to foods rich in fat and carbohydrates such as dates and rice; relative lack of physical exercise, and basically, eating more.

Not everyone gains weight however. One population of ladies in Jordan saw weight and BMI decrease 'significantly' during fasting in 2004, although the average energy and nutrient intake and physical activity was roughly the same before and during Ramadhan. Another Moroccan population of 32 men had lower cholesterol during Ramadhan compared to before it, it was reported in 1997. Triglyceride levels - high triglycerides are an indicator of possible heart disease - also fell. The reductions of both components in the blood were maintained a month after Ramadhan. Meanwhile body weight declined by 2.6% at the end of Ramadhan.

While these studies indicate what could happen for Ramadhan none of them can actually be directly extrapolated to current-day fasting. Other than the fact that the studies are typically done on relatively small populations and should be extended to larger populations, they are usually not repeated over several years. Ramadhan is at a different time of the year every year, so the duration of fasting, ambient temperatures and humidity would vary if it occurs in winter compared to in summer. This means research for Ramadhan in 2000 would actually be studying very different conditions compared to Ramadhan in 2005.

Finally, most of the studies say little about the actual calorie intake of those studied, which could affect the results a great deal. While many would assume that fasting means eating much less, it is quite possible to gain weight during Ramadhan instead. The pre-dawn meal, suhoor, is encouraged but ultimately optional; if taken, it can range from a light meal to a heavy one. The breaking of the fast, or iftar, can be equally light, or feature very rich spreads of Ramadhan delicacies. Some people may also make up for the mid-day meal with a full meal in between iftar and suhoor, or reduce activity while fasting. The end-result could be the ingestion more calories per day than outside of Ramadhan.