Fasting is one of the 5 pillars of Islam. God asks Muslims to fast for one month each year. He says this in the Holy Quran:
185. The month of Ramadân in which was revealed the Qur'ân, a guidance for mankind and clear proofs for the guidance and the criterion (between right and wrong). So whoever of you sights (the crescent on the first night of) the month (of Ramadân i.e. is present at his home), he must observe Saum (fasts) that month, and whoever is ill or on a journey, the same number [of days which one did not observe Saum (fasts) must be made up] from other days. Allâh intends for you ease, and He does not want to make things difficult for you. (He wants that you) must complete the same number (of days), and that you must magnify Allâh [i.e. to say Takbîr (Allâhu-Akbar; Allâh is the Most Great) on seeing the crescent of the months of Ramadân and Shawwâl] for having guided you so that you may be grateful to Him.
[Suarl Al Baqarah / The Holy Quran]
We fast the 9th month in our Hijri Calendar in the Month of Ramadan. Muslims refrain from consuming food and drinking liquids from dawn until sunset. In the Middle-East at this time of year fasting lasts around 16 hours.
God asked us to fast the Month of Ramadan so our hearts would grow greater in Godly fear and reverence. I would say that fasting increases the belief in God and it makes the body and soul more resilient on face of worry and hardship. This does not contradict that fasting can have direct benefits on our health.
This subject is very wide and many researchers wrote about it. Today I would like to present for you some findings that suggest that fasting can improve the functioning of the nervous system.
The National Institute on Aging (USA) has been at the forefront of the Nation's research activities dedicated to understanding the nature of aging, supporting the health and well being of older adults, and extending healthy, active years of life for more people.
Results published on the web site of the National Institute on Aging suggest that food restriction for mice suffering from diabetes leads to improved neural functioning. More specifically, it has been found that a high-calorie diet reduces hippocampal synaptic plasticity and impairs cognitive function, possibly through BDNF-mediated effects on dendritic spines. The results are supervised by Dr. Mark P. Mattson, Chief of the Laboratory of Neurosciences at the National Institute on Aging.
The Hippocampus belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. In degenerative diseases such as Alzheimer's this part of the brain is first to start degenerating.
(Article at Wikipedia)
BDNF, as its name implies, is a substance that increases the growth of new nerve cells in the brain, but it does much more than that. BDNF is neuroprotective against stress and toxic insults to the brain and is somehow–no one yet knows how, exactly–involved in the insulin sensitivity/glucose regulating mechanism. Infusing BDNF into animals increases their insulin sensitivity and makes them lose weight. Humans with greater levels of BDNF have lower levels of depression. BDNF given to depressed humans reduces their depression. And Increased levels of BDNF improves cognitive ability. In short, you want as much BDNF as you can get., and with IF you can get a lot.
Another findings presented by Dr. Michael R. Eades suggest that intermittent fasting (like caloric restriction) reduces oxidative stress, makes the animals more resistant to acute stress in general, reduces blood pressure, reduces blood sugar, improves insulin sensitivity, reduces the incidence of cancer, diabetes, and heart disease, and improves cognitive ability. But intermittent fasting does even more. Animals that are intermittently fasted greatly increase the amount of brain-derived neurotrophic factor (BDNF) relative to CR animals (control group animals i.e. the animals not subjected to intermittent fasting). CR animals do not produce much more BDNF than do ad libitum (at one's pleasure) fed animals.
Fasting the month of Ramadan is obligatory. Yet, many people voluntarily fast once in while all year long. Prophet Muhammad (God's peace and blessings be upon Him) advised His nearest companion Abu Bakr Al Sedeeq (May God be pleased of him) to fast for three days each month. The days are called the white days and they are the 13th, 14th and 15th days in the Hijri month (lunar month). In other words, some people fast the day when it is full moon and the two days that precede it. I had read in the past that fasting those days should counteract the stress and higher degree of arousal that accompanies the full moon. I am not sure how accurate is that. This particular subject needs more research.
Summary, the couple of findings presented here suggest strongly for a relationship between brain health and fasting. Much more is written about this subject. Kindly visit the links below to read more.