Benefits of Fasting For The Brain

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The biggest distinguishing feature which separates humans from other mammals is the size of our brain in comparison to the size of our bodies.  There is, however, another factor which comes into play with our large brains.

That factor is the amount of energy that the human brain consumes. Although it represents 2.5 % of our total body weight, the brain consumes 22% of the human’s energy at rest.  In other words, it takes a lot of calories to keep our brain functioning.

Taking the above into consideration, one has to ask what actually happens in our bodies when there is not enough food?

The human brain developed a unique biological pathway where an alternative source of calories is utilized during starvation.  Let me explain:

Daily food intake provides the glucose the brain needs.  Between meals the glycogen stored in the liver and muscles is broken down and this supply the brain with a steady stream of glucose (blood sugar).  Metabolism shifts when glycogen stores are depleted and gluconeogenesis takes place which involves the construction of new glucose molecules through the harvesting of amino acids during the breakdown of muscle protein.  Muscle-breakdown during starvation is however not good for humans (hunter-gatherers) as we need to move around in order to obtain food.  This becomes a problem when our muscles break down due to starvation and we cannot move or lack the energy to move.

brain health

What Happens To The Human Mind During Starvation?

The human mind becomes very active once food is deprived in order for us humans to find out how to find food.  This mind activity helps protect the brain from oxidative stress and injury.  The mind sharpens when looking for food and at the other end of the spectrum when there is an abundance of food, it dulls the senses making it harder to form associations.

Fortunately, humans have another pathway to provide fuel for the brain – body fat – adding to the factors which distinguish humans from other animals.  When body fat is used as a source of energy, ketones are produced.

Ketones slow down the disease process in the brain, allowing us to remain cognitively engaged, (keep our wits) which in turn allows us to be more likely to survive starvation during a famine.

Let’s face it, none of us are keen to give up our grub for any reason, despite studies that prove that it is a powerful approach to brain enhancement and overall health.  Why would we deprive ourselves of food? It is not the dark ages and food is available in abundance!

What Is Fasting And How Does It Work?

Everybody knows that the human species has been fasting throughout mankind’s history, whether it is for religious reasons, a typical overnight abstinence where you do not eat after a specified time or during more extended periods when food is scarce.

As seen in the Journal of Nutrition, Dr. Clive McCay subjected rats to a daily stringent diet and found a link between metabolism and lifespan in the 1930s. Upon further investigation, it was found that a higher metabolic rate corresponds with increased use of energy by the body, thus leading to shortening the lifespan of test subjects.

Following these studies, two terms emerged:

Caloric Restriction (CR):

Known also as dietary restriction, caloric restriction(CR), the only non-genetic method that extends the lifespan of worms, flies, yeast and rodents which were used as study subjects.  In layman’s terms, caloric restriction refers to constant dieting, eating specific measured amounts of food which do not lead to a deficit in nutrition.

Studies showed a delay in the aging process of up to forty percent in the test subjects with sporadic evidence in humans and non-human primates.  A 2012 NIA caloric restriction study casts a shadow over  caloric restriction, as a ~ 30% restricted diet was used in the study which is very hard to maintain in humans.  This type of diet could be harmful as the molecular effect of caloric restriction proved to be more complicated than what scientists anticipated.

Intermittent Fasting (IF):

Intermittent fasting refers to a shorter period of food intake after a short period of fasting.  In practical terms, eating less every other day or eating meals during 8 hours of the day while not taking in any food for the remaining 16 hours of every 24 hour period.  This means that you could just skip breakfast, eating your first meal at 11:00 am and your last meal before 19:00 pm at night and you are fasting intermittently.  This approach might fit in much easier with daily schedules than measuring specifically cooked meals.  Please note, that it is, however, important to eat the correct foods during the 8-hour window and not binge on fatty fast foods.

Two intermittent fasting trials have been conducted to date.  Dr. James Johnson partnered with Mattson to conduct a clinical trial with 12 overweight subjects with asthma.   Following an alternative day diet, asthma symptoms improved.  Dr. Johnson wrote “The alternative day diet” based on the success of the trial.

Michelle Harvie from the University of Manchester conducted the second trial with 100 overweight women with high risk of breast cancer.  3 Groups each received a different diet: average diet, caloric restriction, and intermittent fasting. The results have yet to be published, but Mattson reported that participants in the fasting group lost weight and improvements in their insulin sensitivity were noted.

The most promising evidence thus far indicates that intermittent fasting does not adversely affect muscle mass, blood glucose levels or cognition which confirms that periodic fasting, unlike long-term calorie restriction (CR) does not lead to the harmful side effects found in calorie restriction.

Professor Mark Mattson (National Institute on Aging USA) promotes intermittent fasting, but does warn that it is not recommended for people over 70, as their brains do not seem to benefit from intermittent fasting – if it does, there would be a very little benefit for the elderly over 70-years of age.  Intermittent fasting is also not recommended for the very young as children need calories to keep them growing.


What Intermittent Fasting Is Not

Intermittent fasting is NOT an extreme form of dieting.  It is also NOT starvation followed by binge eating.  It is simply a method that you could use to time your meals, allowing for regular periods of fasting. At this point, it is important to note that the type of food you eat during intermittent fasting is important as well.  The bottom line or easiest rule to follow is to eat as much possible unprocessed food.   Keep in mind that proteins are needed for the body to function so it is best to avoid the starches and stick to plant-derived proteins. Lean meats, fresh vegetables and a high intake of water are recommended.

Why would my brain benefit from fasting – is fasting not used just for weight loss?

  1. Fasting slows down the onset of strokes, Alzheimer’s, Parkinsons, dementia and other cognitive disorders:

Fasting introduces a mild form of beneficial stress in the body.  When the body enters a state of stress neurochemical changes take place in the brain.  The brain responds to the fasting challenge to cope with the stress and risk of disease.  (The same changes take place in the brain with regular exercise).  Both exercise and fasting are cognitive challenges which increase the production of protein in the brain, which in turn, strengthen synapses,  the growth of neurons and the connections between neurons.

Brain-derived Neurotropic Factor (BNDF) is a protein, which is produced during these changes in the neurochemistry of the brain.  In simple terms,  Brain-derived Neurotropic Factor prevents dying of neurons.  Low levels of BNDF have been linked to Alzheimer’s disease, dementia, and other cognitive disorders.  Fasting increases the level of BNDF which, in turn, slows down or prevent the onset of cognitive disease.

Some case reports also showed that short-term fasts were able to improve Alzheimer symptoms in 9/10 patients.  Animal studies also indicated that intermittent fasting may increase protection against diseases such as Parkinson’s and Huntington’s disease.

  1. Improve memory and learning ability through fasting:

Professor Mark Mattson at the National Institute on Aging, Baltimore, USA reported that the body switch to its fat stores for energy when a person does not eat for a period of 10-16 hours.  Fatty acids (ketones) are released into the bloodstream as a byproduct of burning fat.  These fatty acids or ketones slow disease processes in the brain and protect learning functionality as well as memory.

At the same time, the production of mitochondria in neurons are stimulated as a result of the neurons adapting to the stress of fasting.  This increase in mitochondrial material improves learning and memory ability.

Fasting alone is not enough – working memory brain training can increase the synaptic plasticity in the prefrontal and parietal lobes (areas in the brain involved in cognitive functions) as a study by McNab and colleagues indicated.

  1. Repair of brain cells also known as autophagy:

Brain autophagy is a cleansing process where old, damaged cells are torn down. This process begins when fasting is done for more than 6 hours.  Consider it a self-eating process where waste material is recycled by brain cells and in the process, the brain cells repair themselves.  Human Growth Hormone (HGH) turns on genetic repair mechanisms which in turn creates physiological changes in metabolism to save protein and favor fat burning.

In short, fasting stimulates the production of Human Growth hormone which cleanses the brain cells with weight loss as a by-product as it favors fat burning, to mention but one of the advantages of increased Human growth hormone (HGH).

  1. Keeping the brain young:

Combining exercise and fasting buffers the brain against memory loss and other functions associated with aging as it maintains the brain volume.  A study done by Mark P. Patterson,  based on the results of 30 elderly patients, indicated the following:

  • Performance on memory tests improved significantly in a test group of 50 elderly, normal subjects when their caloric intake was reduced by 30% for three months.
  • Memory and higher cognitive functioning were observed in elderly subjects who exercised for 4 months.
  • Cognitive health is aided by aerobic exercise as it reduces the age-related loss of the brain’s volume. It also contributes to adding volume to gray and white matter in frontal and temporal cortices.
  • When you add brain training to exercise and fasting, multi-tasking and working memory updating also increase – thought processes normally affected by aging such as memory, verbal abilities, fluency and visual-spatial measures in aging also improves.


All human life ends at some stage.  The studies mentioned in this article have proven that a longer life is possible through fasting or restricting your caloric intake through dieting. Additional effects include a healthier brain with better memories which is all we can ask for as we grow older and the time comes when we move on.

The decision to follow a calorie restricted diet or fast intermittently is a personal choice and depends on your lifestyle.  Intermittent fasting is a very practical way to prevent the start of diseases such as brain disease as well as other cognitive disorders.  It also keeps your weight down and overall health in good condition. Proven benefits of intermittent fasting also include keeping your brain healthy, maintain brain mass which shrinks as we grow older and improve memory and learning.

There are undeniable benefits of fasting for the brain, which is already confirmed by scientists and ongoing trials will most likely reveal more benefits.  It might be time to take control of your health and discuss intermitted fasting or caloric restriction action plans with your health professional. The first step might be a change in mindset from We are what we eat to We are how we eat. The benefits to overall health and your brain makes it worth the while to give intermittent fasting.  To Healthy Brains until the end of days!

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