A Functional Patterns Viewpoint on 3 Day Fasts

A Functional Patterns Viewpoint on 3 Day Fasts


The tradition or habit of fasting has always existed in the history of the human race. Whether those fasting periods were forced by the environment (no animals to chase to feed the group) or a deliberate choice for religious reasons, or for other purposes generally linked to improving health and wellness.

The concept of a 3 day fast has been pushed by the health and fitness industry on various podcasts and YouTube channels as a means to achieve optimal health, but there’s also pushback on its effectiveness. 

A 3-day water fast includes refraining from eating or drinking anything containing calories for 72 hours. For a typical 3-day fast, the only permitted consumables are liquids such as herbal, non-caffeinated teas without any additives, or just plain water. Some people may also ingest coffee or black/green tea during their fast, however caffeine in general may have a negative return on investment, as we discuss in another article: The Link Between Caffeine and Anxiety. Despite which one you are considering partaking in, both can be very difficult on physical, mental, and emotional levels.

Throughout this article, we will explore the health benefits of fasting, the mindset and through processes behind fasting, and alternative ways to both regain and maintain a healthy metabolism and weight without straining the nervous system.

Why Participate in Fasting

A 3 day water fast is considered a prolonged fasting diet, any fasting period exceeding 48 hours is considered a prolonged fasting diet. 

Fasting refers to the abstinence from all food and drink, or any part of them, for a specific period of time. Nowadays the method of intermittent fasting seems to be the most commonly used practice. Intermittent fasting consists of alternating periods of fasting and periods of eating. You can decide on a window of time during the day in which you can eat and another one where you fast. For example not eating for 16 hours, either skipping your breakfast or your dinner and repeating the same pattern everyday or several days per week. The health benefits of such a diet are shown in many scientific studies and reviews (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8754590/

They include:

  • Putting the digestive system at rest, give a rest to your stomach and liver 
  • Eliminating toxins and waste by promoting autophagy: intracellular mechanism of protection and recycling of undesirable or damaged cellular elements, a pathogen introduced into the cell, poorly responding proteins etc. Hence promoting cellular regeneration 
  • Weight loss and the ability to maintain the weight lost (if fasting is coupled with ingesting the amount of calories your body needs and not overeat during the eating window)
  • Reducing inflammation: inflammation is a natural response process of an body facing an aggression. However, when it is too important or inappropriate it can be the cause of pathological phenomena

As stated at the beginning of this section fasting for 3 days is not considered an intermittent fast and we will look into what is more specific about that type of fast in the next section. 

The Benefits of Fasting for 3 Days or Longer

On top of all the benefits of intermittent fasting listed in the previous section, a 3 day fast helps your body use even more of the glucose stored as glycogen in your liver and muscles, glucose being the body’s main source of energy production. That glycogen level lasts on average 3 days. The reduction in glycogen stock activates the second physiological energy production system of your body: ketosis (which is the production of ketone bodies). Ketone bodies are made from fat everywhere in the body, even if you are very thin.

Your body is therefore a form of hybrid engine, composed of two energy production systems. The transition from one energy production system to another is normally quite fluid, but the way most people feed themselves nowadays reduces the opportunities for this transition from one mode to another. Longer fasts like a 3 day water fast claim to allow this system to get back into motion and regain flexibility.

Reviewing the Behavior Behind Fasting

In the wellness community, a 3 day fast is usually labeled more as a detox rather than a method to lose weight in a sustainable way, as the weight you usually lose during such a fast is mostly water and can quickly be regained once the fast has ended. It is safe to question what could be the negative externalities of putting one’s body through such a long period of time without any calories ingestion, and the intent behind these types of prolonged fasting diet when done in a repetitive way. 

A popular reason used to start fasting for 3 days or more is the need for a cleanse after a period of overeating. But why does one get to the point of overeating? There is a motivation, a deeper layer, behind the action of overeating that ultimately drove this behavior. To address the behavior, you have to uncover the thought process behind it. Taking the time to identify the preliminary urges, emotions, and traumas that are behind the overeating can help one eventually avoid it all together.

If you’ve ever used the following justifications: “I can eat whatever I want because I can just detox after” or “Why watch what I eat now if I can just start doing that later”, chances are, you have either experienced difficulty sustaining your results, or you have failed to meet certain health or weight goals on a planned schedule. That’s because overeating or fasting itself isn’t the sole issue, but it’s the experience, or the psychological state of mind, that is driving it. 

If you want to promote a healthy metabolism and a well functioning body, we suggest that fasting, especially whenever it’s over 24 hours, be used as a tool. When fasting is abused, such as a band-aid for dietary blunders, or a quick solution for weight loss, the results are unsustainable and usually conclude in more harm than good. 

At Functional Patterns, we are not against the idea of fasting: We often recommend people to try fasting or intermittent fasting to reset their diet or specifically explore the mental and emotional dependencies they may have on food. We also ask clients or those suffering from chronic pain, to eliminate certain foods that are proven to cause inflammation in the first place, such as processed food, grains (The Uncomfortable Truth about Grains), and PUFAs (polyunsaturated fatty acids) (Top Foods to Avoid if you Want to Perform Better). 

One of the main benefits of fasting is to reduce inflammation in your body. If you adopt the ability to slowly eliminate food that initially triggers inflammation, the need to go through extreme periods of fasting to reduce that aspect becomes less important. 


Downsides of Fasting

A 3 day fast or any fasting period longer than that will inevitably put a certain amount of stress on your body. During the first 48 hours of a fast your sympathetic nervous system (which primary function is to activate your body’s fight or flight response) will get into action and your body will start using your stock of glucose. When your body has adapted to that it is supposed to get more controlled by the parasympathetic nervous system to start the autophagy process. However getting into that relaxed mode is not a given and you might just keep producing a larger amount  of stress hormones involving a higher level of inflammation when you are trying to achieve the opposite. 

Constantly shifting from long periods of fasting and back to regular eating or even overeating, will inevitably put stress on your body. If we look at the bigger picture, in your quest of feeling healthy to have a well functioning body, your diet should not be the only thing to consider. Functional Patterns clients from our results page who were struggling with weight loss or eating habits started to address their problems once they started fixing how they moved their body in their environment, otherwise known as biomechanics.


A More Sustainable Option


Addressing weight loss and eating habits goes much deeper than just considering how long you should or should not fast. We all have a tendency to have our bodies twisted in one direction or another. You might notice certain asymmetries that exist in your body or in your movement. For example, maybe your right shoulder turns in much more than the left one; or your torso might be rotating more to the right; or maybe you constantly feel like you’re using your right knee much more than the left one, etc. These are biomechanical problems locking your body in a constant state of compression. 

There seems to be an associative set of responses we have in relation to the spirals we are stuck in. Whenever you find it hard to change your behavior towards food, or even towards repeated activities with negative returns (such as overspending money or making time investments in people that cannot reciprocate your efforts), you are operating from a state of deficiency that keeps you stuck in a  loop of coping response mechanisms. As the founder of FP, Naudi Aguilar puts  it:

“Until you address those imbalances and start to close that loop within your body and you start feeling good within your own body and within yourself, you are going to keep seeking things externally to account for the crises that are going on inside your body”

The more you address your mechanical problems in a relevant manner by focusing on the movement blueprint us humans have evolved with, the more reliable and healthy your body will feel. As a result of focusing on correcting your movement and body, your cells will be able to regenerate and your nervous system can more effectively enter a parasympathetic state from a stressed state.

The more often you are able to achieve a parasympathetic state for downtime and recovery, the more your body will start to instinctually desire certain foods that help you sustain your progress. If your relationship with food was already average in the first place, you will start feeling that the inflammation you might have had before is reduced without you having to regularly go through something like a 3 day fast.




Fasting is a healthy way to maintain a balance in your digestive system and in your body in general. However the way you do it and the reason why you do it matter. Intermittent fasting done in a relevant and practical way can definitely help you get some benefits in a sustainable manner. It is however fair to question the kind of strain a 3-day water fast can put on your body. Although questioning our food intake is important at Functional Patterns we know that the main thing that needs to be addressed is the imbalances in your mechanics. A well balanced body will be much more resilient and will have a better way of breaking down what you are ingesting and use it as fuel without you having to regularly go through some strenuous periods of cleansing. 

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