The Effects of Intermittent Fasting on Brain Function

What Is Intermittent Fasting?

Intermittent Fasting is not a diet led activity; it is more of a dieting sequence. It is where you purposely avoid eating food at specified points in time. You have a calorie intake during certain parts of the day and then refrain from eating for a larger portion of time than you spend eating.

It goes without saying that eating a balanced and nutritious diet is integral to your health and well-being. However, intermittent fasting works because often when you eat can also influence the reaction of your body to food.

How Does Intermittent fasting work?

When you eat, it takes your body between 2-4 hours to digest and processes the food.  Directly after you eat, the body will take its energy directly from the food you have just consumed and not from fat stored within the body.  When you are fasting, there is no food source for the body to obtain energy from, as such, it goes to the next available source which is the fat sources you have stored within your body.

Essentially, Intermittent fasting encourages your body to use what it consumes more effectively, using the fat that is stored for fuel when you are fasting.  When done correctly, it helps you build muscle and burn fat.

How to Get Started with Intermittent Fasting 

Getting started with Intermittent Fasting is relatively easy. There is a period of the day that you eat nothing, then a window where you consume your daily calories. The fundamental rules of a nutritious and correct diet still apply.

  1. Choose which type of Intermittent Fasting you are going to do.

  2. Then you need to work out how many calories you need to consume on any given day.

  3. Work out your macronutrients. A great app to work this out for you is listed

  4. Establish a meal plan and schedule.

Different Types of Intermittent Fasting (IF) 

Whole Day Fasts

This is probably the easiest form of intermittent fasting and involved 1-2 days of total fasting weekly.  This also includes unrestricted eating across all other days of the week. It is also known as Eat-Stop-Eat.

Fasting-Feeding Splits

There are two commonly regarding methods namely The Warrior Diet and The LeanGains method which fall into this category and provide examples of what this type of intermittent fasting is all about. Essentially, there is a fasting period and an eating period which each have a specific number of hours dedicated to each.

With the Warrior Diet, all of your daily intake of calories are eaten within a four-hour window, the other 20 hours of the day are fasting hours.  The LeanGains method involves eating your daily intake within an 8-hour window, with the other 16 spent fasting.

Alternate Day Fasts

Also referred to as ADF. This type of fasting will alternate between fasting days and unrestricted day. It is considered normal practice to have a single meal around midday when doing ADF that contains around ¼ of your normal calorie intake. There are many individuals who choose to forgo these meals. However, a lot of the research studies that are carried out will generally tend to include this singular meal.

Normally, you are not meant to consume any calories whatsoever during a fast. However, you can have black coffee, tea and sugar-free gum.  

Whichever option you choose, you need to be mindful of your calorie intake.

Intermittent Fasting Impacts Brain Function 

Fasting has phenomenal advantages in relation to a range of different brain functions. Perhaps the most significant of these comes from a cellular cleansing process known as autophagy activation.  Humans and mammals alike respond in similar ways when they are deprived severely from calories, and the size of most of their major organs will shrink, that is, except for the brain and the testicles.   It is said that this is to protect the survival of these species and it makes a lot of sense, on both counts.

What is Autophagy Activation? 

Autophagy is essentially where the body will eat itself. It sounds a little scary, but is actually one of the best things you can train your body to do.  It is the natural way for the body to clean itself from the inside out. 

Autophagy plays a crucial role in your body’s ability to regenerate, repair and detoxifies itself. By activating this process, you can reduce inflammation, optimise your brain functions and slow down the aging process.  Plenty of Research has been conducted which proves that fasting promotes autophagy within the brain. It can increase neuroplasticity, cognitive functions and improve brain structure.  Intermittent fasting is a proven way to activate autophagy.

History Prevails

Although this fact might be unknown to many, it is a topic that has been highly researched, and the benefits of fasting have been known for a long time now.   If you consider way back when cavemen were around, and food was a little scarce during winter months; if the normal functioning of the brain were to slow down on such occasions where food was limited, it would have made it almost impossible for those individuals to function and hunt for food.  However, it has been proven time and time again that an elevated cognitive function is attained during periods of fasting.  

Another historical example of this can be found in Ancient Greece, where it was common practice for ‘The Great Thinkers’ to fast in order to enhance their mental agility.  Even back then, it was highly regarded that starvation had a proven ability to sharpens one mind and increase the cognitive ability respectively.  

Recent Studies Showing the Effects of Fasting on Brain Function 

Professor Mark Mattson, the current Chief of the Laboratory of Neuroscience at the National Institute on Ageing and Professor of Neuroscience at The Johns Hopkins University, gave a TEDx talk on the subject of fasting and its effects on the brain. He reported studies showed fasting caused positive neurochemical changes to occur in the brains of test subjects, which lead to an improvement of cognitive function and resistance to stressful stimuli. These studies also showed calorific restriction reduced inflammation in the brain and increased neurotrophic factors such as the production and growth of neurons (which help with learning and memory).

Professor Mattson also reported studies indicated fasting constitutes a challenge to the brain. The brain reacts to this challenge by adapting response pathways to help it cope with stress.

Interestingly, Professor Mattson outlined the brain’s reaction to intermittent fasting is the same reaction it has to regular exercise. Both activities affect increasing protein production in the brain, which then promotes the growth and connection of neurons and strengthens synapses. Both practices also stimulate the production of nerve cells in the hippocampus, stimulates the production of ketones (“petrol” for neurons) and increases the number of mitochondria within neurons, which in turn help the neurons to maintain their connections. All of this has the net effect of improving memory and increasing the ability to learn. 

He also said there were some indications “intermittent fasting enhances the ability of nerve cells to repair DNA.” If this is the case, it may be a good topic for research to concentrate on when examining preventative measures and possible treatments conditions such as Dystonia and Dementia. In fact, according to Professor Mattson, some research which has been in this space has already shown positive results.[1]

One aspect of the research particularly interesting to note is that benefits were not related to a calorific restriction in general, but with specific intentional periods of intermittent fasting. 

All indications show that intermittent fasting not only has positive effects on your body, like weight loss and improvement of risk factors in respect of heart disease, diabetes and the like; it also has an extremely positive effect on your brain, allowing increased levels of focus and memory retention.

Intermittent fasting, in particular, may lead to improvements in memory and learning, as well developing a greater resistance in the brain to conditions such as Dystonia, and Dementia.


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