Fasting: Where Religion Meets Evolution

 Fasting:  Where Religion Meets Evolution

M. Bakri Musa

 

 

The Qur’an exhorts us to fast as “ . . . it was decreed for those before you, that you may attain salvation.” (2:183; approximate translation.)

 

            Taking a much broader or stretching the meaning of “those before you” to include our hunter-gatherer ancestors, extending the meaning of fasting to mean sustained periods without food, and interpreting salvation to mean survival, the essence of that ayat is one of the few certitudes that both faith and science share.

 

            The signal difference between the fasting (or periods without food) of our hunter-gatherer ancestors versus the current practices of many faiths, as well as health enthusiasts, is the factor of volition. Unlike our ancestors who had to endure periods without food because of the environment, as with poor hunting seasons, today’s faithful and health enthusiasts choose to forego food for specified periods of time.

 

            Our biology however does not appreciate such differences. The net effect of food deprivation, whether intentional or otherwise, on our metabolism is the same. The evolutionary energetics (the study of energy and its transformation) of our hunter-gatherer ancestors to cope with periods without food are still operative and called upon today in those who fast. Principally this is the “metabolic switching,” of using glucose as the principal source of energy in times of plenty versus relying on stored body fats during fasting or periods without food.

 

            In the last few decades biologists have used this insight to help elucidate the dynamics of our evolutionary pathways, supplementing in very major and revolutionary ways the evidence garnered through such traditional sources as fossil studies of bone (in particular skull) sizes and shapes. For this we owe a huge debt of gratitude to our contemporary fellow humans who still retain our ancestral hunter-gatherer lifestyle, the Hadza tribe of Central Africa.

 

            Using doubly-labeled water, ²H₂¹⁸O (DLW–where the hydrogen has an extra proton and the carbon, an extra pair), for their subjects to drink, biologists could estimate the “free-living energy expenditure” of an individual. Energy is and reflects life; no energy, no life. Incidentally these experiments with DLW were first done on the military.

 

            The major consumption of energy for our ancestor hunter-gatherers, as extrapolated from studies on the Hadzas, is directed towards the twin purposes of brain function and reproductive capacities. That makes teleological sense as the former is for immediate self-survival; the latter, species survival.

 

            For our ancestors, periods of food deprivation were the norm. It was only much later when they discovered agriculture that they settled on the land, their foods now assured through farming. While they had plants as food earlier as with their fruits and leaves, those too were seasonal.

 

            Beyond that, their discovery of metals that could be fashioned as killing tools, as well as the utility of fire beyond keeping themselves warm, as with cooking and preserving their hunted meat, were consequential. Dried meat buffered their hunting droughts. With cooked meat they could dispense with huge jaws, thus preserving precious skull space for the brain.

 

            Beyond those visible anatomical changes, deep in our cellular innards were even more consequential changes with our basic metabolism, specifically energy production. In times of plenty we burn glucose and store the excess as fat. Glucose is what powered our muscles as well as the brain. In times of scarcity we burn fat, the by-products being ketone bodies which the brain could use but not muscles. We could burn muscles to produce glucose (gluconeogenesis), but that would be self-destructive, akin to depleting our capital. We need muscles to hunt. Weak muscles equal no kill and thus no food.

 

            The ability of the brain to use ketones, and very effectively too, again makes teleological sense. When times are tough we need our cognitive ability more than ever to strategize and hunt smarter. No surprise that ketogenic diet is now used to enhance cognitive ability. It has long been the mainstay to prevent convulsions of childhood epilepsy. The spiritual enhancements of ascetics as well as the heightened spirituality of Muslims during Ramadan reflect this. Their commonality with marathon runners who fast before major races may be mediated through the effects of these ketone bodies on the brain.

 

            In contrast to the positive evolutionary changes with fasting through the ensuing ketogenic diet, starvation is destructive. With the latter, with fat being depleted, you start burning muscles. That undermines your strength and physical integrity. You need muscles to hunt or even to breathe. The vicious cycle continues until you die. The clinical manifestation of this is anorexia nervosa, a condition where the individual loses any desire to eat.

 

            We should leverage this role of ketosis during fasting. It is no surprise that mosques are full during Ramadan because of this enhanced spirituality. Ramadan is my most productive time intellectually. During lunch hours I can work uninterrupted. The hour before the breaking of fast, being too tired to do any physical work, is spent reading; likewise the early hours after suhor (the predawn breakfast). I enjoy a quantum leap in my reading during Ramadan.

 

            Rumi encapsulated it best:  Fasting blinds the body in order to open the eyes of the soul. In modern biological parlance, that would be enhancing our central neuronal connections. Or as per my Imam Ilyas, Ramadan is the time for us to get closer to Allah. May this Ramadan achieve this as well as bring peace and prosperity to all.