Did you know fasting can improve your cognition, be used as a form of therapy and may even help slow down aging processes?

This month, hundreds of Muslim students at USask and millions across the world will be observing the Islamic holy month of Ramadan, fasting every day for 29-30 days straight. Students will eat suhoor, their morning meal, before the sun rises and go on with their normal daily tasks until sunset, when they break their fasts at iftar. During their fasts, the period between suhoor and iftar, students will be refraining from eating and drinking any food or beverage. 

The tradition of fasting has been in place across various countries, cultures and religions for centuries, for various spiritual reasons. `While fasting has become a popular practice in the fitness and health industries as a method of weight loss, it is also used as a form of therapy for some neurological disorders and chronic illnesses, and can even help with recovery from chemotherapy. What sets the practice of fasting during Ramadan apart from other forms of fasting is the abstinence from all food and drink, and the duration of the fasting period.

Researchers have discussed and analyzed the practice for years to understand the effects that a month-long period of fasting can have on the human body. Like any other diet, there are both positive and negative effects. However, studies generally conclude that the practice of fasting during Ramadan can have various health benefits, and is a safe practice that boosts overall wellbeing.  

Here are some notable positive effects that long periods of fasting can have on the human body:

Lower Cholesterol 

Studies have shown that fasting can significantly reduce low-density lipoprotein (LDL) cholesterol levels, increase high-density lipoprotein (HDL) cholesterol levels and improve the circulation of total cholesterol and triacylglycerol levels. 

During prolonged intermittent fasting, the body undergoes metabolic adaptations to adjust to the new timing of food intake. Instead of relying on external sources for energy, the body begins to take from internal sources (a process also known as metabolic switching). Typically, the body gets its energy from glycogen in the liver, but as the human body only has a small amount in reserve (enough for 2-12 hours), it eventually begins to burn fat for energy when food is unavailable. 

As a result, triglycerides (small fat molecules) are released via adipose tissue into the bloodstream with the help of lipases. These triglycerides break down into fatty acids and glycerol, travel to the liver, and are converted into ketone bodies, which are used as a source of energy. 

With this metabolic change from glucose to ketones, the body starts to use lipids instead of reserving them, moving them out of the cells, through the bloodstream and into the liver to create ketones as well. With this change in lipids direction, the body must accommodate the amount of cholesterol needed to facilitate the transfer. As a result, HDL levels increase and LDL levels decrease.

High levels of HDL and low levels of LDL suggest a smaller likelihood of plaque buildup in the walls of blood vessels, reducing the risk of stroke and cardiovascular disease. 

Fasting also improves key components of metabolism such as insulin sensitivity, lipid metabolism and autophagy—the cellular stress response through which old, damaged or abnormal proteins and other substances are broken down and eliminated. 

This also promotes beneficial changes in the gut microbiome, increasing microbial diversity and favoring the growth of bacteria with anti-inflammatory properties, which contributes to overall health.

While several studies support these findings, the effects of fasting on cholesterol metabolism vary among individuals. Factors such as diet composition, metabolic rate and individual physiological differences influence the extent of these benefits.

Reduced Inflammation and Boosted Immune System

Studies have shown that fasting has an anti-inflammatory effect on the body, suppressing pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP) while reducing systemic inflammation independent of caloric intake and sleep patterns. Fasting also reduces oxidative stress by decreasing reactive oxygen species (ROS) and enhancing antioxidant enzyme activity, which helps protect cells from damage, leading to anti-inflammatory effects.

The body’s immune system largely relies on the gut microbiome. Studies have shown that, in both human and animal models, fasting may potentially increase the presence of protective bacteria within the gastrointestinal tract and decrease intestinal inflammation.

Research has also shown that fasting can induce immune cell regeneration. To conserve energy during fasting the body breaks down white blood cells and kills off any defective immune cells. This process can also induce immune cell regeneration and increase the amount present in the body.

Cells that support immune response leave the bloodstream when nutrient levels decrease, migrating to the nutrient-dense bone marrow, where they regenerate and become ‘supercharged,’ now better able to resist infection and attack foreign pathogens.

Through these mechanisms, fasting can enhance immune function and potentially improve the body’s resilience against chronic illnesses like cardiovascular disease, type 2 diabetes, and autoimmune disorders. Research also suggests that fasting may strengthen the body’s defense against infections and contribute to longevity by promoting cellular repair processes.

Improved Cognitive Function

Multiple studies have shown that fasting can significantly impact brain function.

Fasting has been found to stimulate neurogenesis—the production of new neurons—and enhance synaptic plasticity, which plays a crucial role in regulating pain perception and supporting the brain’s built-in anti-aging mechanisms. It has also been suggested that it can stimulate protein synthesis, which enhances learning and memory as well.

The brain’s ability to respond to external stimuli depends on the plasticity of its synaptic connections. The formation and maintenance of these connections are increased by the activation of synapses and signalling pathways stimulating stress responses. This associative and input-specific synaptic plasticity is considered the cellular correlate for multiple cognitive processes, such as learning and memory. 

Fasting increases quantities of brain-derived neurotrophic factor (BDNF), a protein widely present in the brain and essential for learning, memory and mood regulation. Higher BDNF levels are associated with improved cognitive performance and memory, as well as a greater resilience to stress and depression.

The capacity of BDNF to promote new functional neurons is essential for learning and memory formation. BDNF has been established as a critical regulator of synaptic plasticity in distinct brain regions such as the hippocampus and cortex. The hippocampus subregion dentate gyrus retains the ability to form new neurons throughout life, which suggests an increased ability for learning and memory acquisition. 

Furthermore, fasting triggers cellular stress response pathways that enhance neuronal resilience by promoting repair mechanisms and strengthening the brain’s adaptability, which contributes to overall brain health. 

Protection Against the Onset of Neurodegenerative Disorders

Studies into the relationship between diet and brain-related disorders such as Parkinson’s disease, Alzheimer’s disease, Multiple Sclerosis, Epilepsy and Stroke have argued that CR may have the potential to treat or prevent such illnesses.

It has been suggested that CR can decrease the neurocognitive decline that leads to neurodegenerative diseases by stimulating stress-resistance pathways and suppressing inflammatory processes.

Fasting impacts brain function via various mechanisms including changes in neurotransmitter levels, and alterations in energy metabolism. By promoting ketone production, fasting provides an alternative energy source for the brain for a short period (in a hypermetabolic state), which may enhance cognitive function and increase the brain’s ability to protect against neurodegenerative diseases.

Fasting may promote the growth of new neurons within the hippocampus—the area of the brain associated with learning and memory—a process that would contribute to improved cognitive function and a reduced risk of neurodegenerative diseases. Research has also suggested that fasting can even reduce neuronal insulin resistance and the pace at which the brain ages, as well as improve memory and executive function globally in older adults. 

Delayed Cellular Aging

Calorie restriction (CR) has been shown to work as an intervention to extend lifespan in nearly all animal models. 

Fasting can increase Sirtuin signalling in the body, which has been found to increase lifespan in numerous species. Sirtuin signaling is linked to autophagy, and the increased autophagy under a CR like fasting may possibly contribute to an increase in lifespan. 

Autophagy can improve cellular longevity and prevent cell death during CR. In mice, autophagy under CR can lead to a higher tolerance against cellular deterioration caused by chemotherapy, suggesting that the benefits of this process induced by CR are due to autophagy’s ability to limit the accumulation of damaged and dysfunctional materials. 

Sirtuins are a family of nicotinamide dinucleotide (NAD+)-dependent deacylases that delay cellular senescence and regulate DNA repair, fat differentiation, glucose output, insulin sensitivity, fatty acid oxidation, neurogenesis and inflammation. They also help in disease prevention and in reversing some aspects of aging. 

Sirtuins promote lifespan extension by regulating a variety of cellular processes. They help prevent cellular senescence primarily by slowing down age-related telomere shortening, maintaining genome stability, and promoting DNA repair. Additionally, Sirtuins influence overall lifespan by interacting with signaling pathways that regulate aging, like the insulin/IGF-1 pathway, AMP-activated protein kinase (AMPK), and forkhead box O.

The subcellular localization SIRT1 plays a critical role in cellular processes such as cell cycle regulation, cell metabolism, DNA repair, and aging. It is also associated with oxidative stress responses, inflammation and immune response, and can affect insulin secretion. 

CR boosts the expression of SIRT1 in the hypothalamus, a region of the brain that regulates physiological decline and links the neuroendocrine system to various bodily functions. Research in mice suggests that SIRT1 in the brain influences the secretion of hypothalamic and pituitary hormones, which may play a role in the aging-delaying effects of CR in mammals.

Final Thoughts

With all that being said, there is still plenty of research that needs to be done on the practice of fasting. Scientists continue to investigate the complex biological processes triggered by fasting, and future studies may reveal even more about its long-term effects. 

As millions worldwide observe Ramadan this month, fasting remains not only a deeply rooted spiritual practice but also a subject of growing scientific interest for its potential to promote overall well-being.

Ramadan Kareem to all those who observe!