Muslims around the world are currently observing the holy month of Ramadan with gratitude to Allah SWT. Even though the status of the Covid-19 pandemic has not been officially declared over, the situation is getting better. This time, we are allowed to perform tarawih prayers in congregation, tadarus and iktikaf at the mosque, and are no longer obliged to wear masks. The coverage of the first booster vaccination has reached around 75%, the second booster is around 68%, and approximately three million people having received the third, so it is much safer because herd immunity has been achieved. These are all the blessing of Allah SWT for which we Muslims are grateful.

Fasting during Ramadan is an obligation for Muslims, as stated in Surah Al-Baqarah verse 183: "O you who have believed, fasting is prescribed upon you, as it was prescribed upon those before you, so that you may be pious". The purpose of fasting, among others, is to be more restrained, to control passions, to cultivate patience, to empathize with the poor, to cultivate social sensitivity, and to have the courage to uphold justice and truth.

Ramadan fasting does not only have a ritual dimension, but also in all aspects of life, including the medical dimension. Fasting is a method to nourish the body, which has been applied by highly civilized nations for thousands of years, even before Islam. Several ancient civilizations, such as the Greeks, Romans, Egyptians and Chinese, were familiar with the culture of fasting for various purposes, from religious rituals to health purposes. The Romans, for example, used fasting as a diet method, and the ancient Chinese practiced fasting as a detoxification method, to cleanse the body of toxins that accompany food.

Medically, fasting has been shown to promote nitrogen balance, reduce inflammation, and have an invigorating effect on the body. By looking at its history, Ramadan fasting has roots in the fasting culture of highly civilized nations thousands of years before. This has become evidence-based medicine in the modern medical era. A review of evidence-based clinical studies on Ramadan fasting has at least been discussed by Valter D. Longo and Mark P. Mattson in their article: "Fasting: Molecular Mechanisms and Clinical Applications" in the journal Cell Metabolism (2014); 19(2); 181-192. By fasting completely during the month of Ramadan, the body experiences a calorie reduction of around 465 kCal or about 25 percent of daily intake if not fasting. At least, this is where fasting functions as a diet, a method for reducing obesity and maintaining good health. Such eating limitation with complete and balanced nutrition, will prevent disease potentials that results from excess food.

 This principle can also be applied to fasting outside of Ramadan to keep the body and soul healthy. For example, Muslims have various sunnah fasts, such as the Monday-Thursday fasting which was later adopted into the Javanese tradition, David's fast (a day of fasting, a day of not), Shawwal fast, and other sunnah fasts. Today many clinics use fasting as a method of treatment in the medical field, such as for treating obesity or preventing certain diseases. In this case the patient can undergo very low-calorie fasting, less than 200 kCal/day, and for a certain duration and under the supervision of a doctor. Additionally, we actually fast every day, that is by sleeping at night until morning. In English, therefore, the first meal of the day is called "breakfast" because it "breaks the fast".

Fasting in medicine

Physically, refers to the state of abstaining from food and drink for a set period of time. According to fiqh, the duration of Ramadan fasting starts from the arrival of the dawn prayer until the arrival of the sunset prayer. The length of this period varies depending on the geographic location, ranging from 11 to 22 hours.

In English, the term "fasting" typically connotes the experience of hunger and malnutrition.  Indeed, starvation in chronic conditions, for example only receiving intakes below 100 kCal per day and for a very long time, can be fatal. However, it is important to distinguish between fasting and starvation. Ramadan fasting or other fasts, is to stop the intake of food and drink into the body for a certain period of time. There is a long time lag (from dawn to dusk) in order to get some controlled catabolic processes. This is also different from dieting, which is a reduction in calorie intake to a certain amount, for example a maximum of only 30% of usual, but the frequency of eating is maintained and there are no strict meal intervals.

Several studies in both animal and human subjects have demonstrated that fasting has numerous benefits, such as improving brain function, increasing nerve cell synthesis, protecting against neurodegenerative conditions such as Alzheimer's and Parkinson's diseases, and delaying the aging process. In medicine, fasting is also utilized for diagnostic purposes. For example fasting before a blood test to ensure more accurate results. Temporary nutritional intake can mess up measurements, blood sugar levels or cholesterol triglyceride levels can be detected high due to a false positive or inaccurate signal caused by a momentary influx of nutrients. For this reason, it is recommended to fast for 9-10 hours before a blood test.

Furthermore, fasting is also intended for medical procedure such as surgery to prevent food from entering the respiratory tract. During surgery under general anesthesia, digestive tract movements are halted/paralyzed due to the effects of anaesthesia. To prevent aspiration,  or the entry of food into the respiratory tract, the stomach must be emptied by fasting or by using a laxative.

The biological role of fasting

The biological function of fasting involves the body's ability to adapt to changes in nutritional intake. Typically, humans have a regular pattern of eating every 8 to 14 hours to maintain bodily functions and prevent illness. However, during Ramadan fasting, the time lag between meals changes to 11-22 hours, causing the body to establish a metabolic control system to regulate nutrient flow and organ function during the fast.

During fasting, the body will automatically conserve energy, due to a gradual decrease in physical activity If the duration of fasting is prolonged, physical activity will continue to decrease, leading to a reduction in energy consumption and resting metabolic rate. Even though there is no protein calorie intake within a certain range, energy needs for the body's metabolism can still be met during the fasting period because the body is equipped with a warning system that involves nervous and hormonal responses. This mechanism can recognize a lack of calories with a span of 24 hours, and respond to it as a form of compensation for the body through a catabolic process.

To overcome the lack of nutrients and reduce the effects of hunger during fasting, the body seeks alternative energy sources. Within the first 24 hours of fasting, the body uses available blood glucose-fatty acids and liver-muscle glycogen as an energy source. However, this amount is insufficient to meet the body's daily metabolic needs. If no nutritional intake occurs, the body breaks down triglycerides into fatty acids and ketones, which are used by non-brain tissue as energy sources. The brain, on the other hand, uses only glucose to produce energy, using approximately 5 grams of glucose per hour. However, the brain is also capable of using ketones as an energy source, whether awake, sleeping, or thinking.

Mark P. Mattson, a neurologist at Johns Hopkins University School of Medicine, explains that during normal conditions, the liver stores glucose, which is used as the body's energy source before it is converted into fat. It takes about 10 to 12 hours to deplete the glucose stored in the liver before the body switches to burning stored fat for energy. When food is consumed, glucose is used for energy, with any excess being stored in the liver and fatty elements being stored in adipose tissue. However, during fasting, once the glucose is used up, the body breaks down fat deposits and uses them for energy, although at a slower metabolic rate.

For those trying to lose weight, it is important to fast for 16 hours without adding calories. However, Mattson, who has studied the health effects of intermittent fasting for 25 years, suggests an easier way: stop eating at 7 pm, skip breakfast the next day, and eat again at 11 am. This method is known as the 7:11 diet, as written in The New England Journal of Medicine. In short, this pattern is formed by eating in limited time each day, by narrowing the time span of eating to 8 hours per day.

While habitual fasting can lead to gradual weight loss, the challenge in managing obesity is maintaining weight loss. Obesity is an eating disorder that cannot be resolved simply by reducing food intake because the body becomes less responsive to the internal signals that regulate eating behavior.

Other health benefits of fasting

The advantages of fasting extend beyond calorie reduction, weight management, and nutrition; there are more intricate benefits as well. For instance, fasting can regulate illnesses stemming from food or dietary intake, such as heart disease and diabetes. Intermittent fasting can reduce various risk factors, including blood pressure, cholesterol, triglycerides, and blood sugar.

Interestingly, fasting can improve blood sugar regulation by decreasing insulin resistance, which is especially valuable for those susceptible to developing diabetes. One study conducted on ten type 2 diabetes patients demonstrated that short-term fasting can considerably lower blood sugar levels. Another review of studies discovered that intermittent fasting is just as effective as calorie restriction in reducing insulin resistance, enhancing the body's sensitivity to insulin, and facilitating the more efficient transfer of glucose from the bloodstream to the body's cells. Consequently, fasting can help prevent erratic fluctuations in blood sugar levels, keeping them steady.

Based on the above explanation, it can be inferred that both obligatory and voluntary fasting provide numerous benefits for the body and soul's health. For Muslims, fasting during Ramadan is obligatory, and its significant health benefits are a blessing that merits appreciation. Therefore, let us continue our Ramadan fast with joy and gratitude in the hope of receiving abundant blessings.

Djoko Santoso
Professor, Faculty of Medicine, Universitas Airlangga
Chairman of Health Department, Indonesian Council of Ulama, East Java