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Intermittent Fasting 101: Everything You Need to Know for a Successful Fast

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Intermittent fasting has been a hot topic recently, as a lot of influential internet personas are encouraging people to fast. The way I heard about fasting is from a Joe Rogan podcast episode. I got more intrigued, and I directly moved to Andrew Huberman’s 2-and-a-half-hour-long episode on intermittent fasting and time-restricted eating. Since then, I’ve restricted my eating period to 8 hours (eating only from 11 am to 7 pm), and fast for 16 hours. My honest opinion – I have never felt better in my whole life. 

If you’re new to fasting, the amount of information can be super overwhelming. Thus, if you don’t know where to start – don’t worry, I got you covered. In this article, we will cover the types of fasting, the health benefits, potential risks, and tips for successful fasting. This article will be covered by studies and personal experience. 

What is intermittent fasting

Let’s start with one question what is intermittent fasting? Well, there is no formally accepted definition for fasting, as this study by the University of Glasgow suggests. But to explain it in short – Intermittent fasting, also known as time-restricted feeding, involves eating during specific periods of the 24-hour cycle or not eating for entire days.

Types of Fasting

Intermittent Fasting:

  • Intermittent fasting involves cycling between periods of eating and fasting. The 16/8 method restricts eating to an 8-hour window daily, while the 5:2 approach involves regular eating for five days and restricting calorie intake on two non-consecutive days.
  • Intermittent fasting may aid in weight loss, improve metabolic health, enhance brain function, and provide other health benefits.
  • Misconceptions may include the idea that fasting always leads to extreme hunger, or that it is detrimental to metabolism. However, when done correctly, intermittent fasting can be a sustainable and beneficial practice.

Water Fasting:

  • Water fasting involves abstaining from all food and beverages except water. It is a complete restriction of caloric intake for a specific duration.
  • Benefits may include autophagy (cellular repair) and improved insulin sensitivity. Risks can include electrolyte imbalances, nutrient deficiencies, and potential adverse effects in certain health conditions.
  • Duration and considerations: Water fasting durations can vary, from 24 hours to several days. Considerations include individual health status, hydration, and the need for medical supervision.

Extended Fasting:

  • Fasts lasting more than 48 hours: Extended fasting typically exceeds 48 hours and can extend to several days or even weeks.
  • Potential benefits and risks: Benefits may include enhanced autophagy, fat loss, and metabolic improvements. Risks may involve nutritional deficiencies and complications, particularly without proper supervision.
  • Medical supervision and safety: Extended fasting should be done under medical supervision, especially for periods beyond a few days. Safety measures include regular health monitoring and addressing any emerging concerns promptly.

Health Benefits of Fasting

Probably the biggest benefit of intermittent fasting is that it help lower the blood glucose of an individual. A recent study from 2021 named “Fasting blood glucose as a predictor of mortality: Lost in translation”, concludes that a higher blood glucose is associated with mortality in humans, while lower blood glucose predicts mortality in mice, highlighting species-specific differences in research translation. For me, that’s a pretty dope benefit!
Now, before I talk about the other amazing benefits of fasting, this video of the Joe Rogan Experience, episode 1108, gives a great overall context of some intermittent fasting benefits.

Weight Management

How fasting affects metabolism:

Fasting plays a significant role in influencing metabolism by altering the way the body processes energy. During periods of fasting, especially in extended fasts or intermittent fasting, the body shifts from utilizing glucose as its primary energy source to burning stored fat. This metabolic shift promotes fat oxidation and contributes to weight loss over time. By tapping into fat stores for energy, fasting can be an effective strategy for those looking to manage their weight.

Research findings on weight loss:

Numerous studies have explored the connection between fasting and weight loss, consistently demonstrating positive outcomes. A Harvard research suggests that intermittent fasting, in particular, can lead to a reduction in body weight and body fat percentage. Additionally, extended fasting periods have been associated with more significant weight loss results. These findings underscore the effectiveness of fasting as a viable approach for individuals seeking sustainable weight management.

Improved Insulin Sensitivity

Impact on blood sugar levels:

Fasting has been shown to have a positive impact on blood sugar levels, especially in individuals with insulin resistance or diabetes, as shown in “Effects of intermittent fasting on health markers in those with type 2 diabetes: A pilot study”. To know the positives to your body, this is best done by buying a blood glucose monitor. By abstaining from food for specific durations, fasting helps regulate insulin production and sensitivity. This, in turn, contributes to better blood glucose control. For those with diabetes, incorporating fasting under medical supervision may be a complementary strategy to manage and improve their condition.

Benefits for individuals with diabetes:

Fasting can offer valuable benefits for individuals with diabetes, including improved insulin sensitivity and enhanced glycemic control. Some studies suggest that intermittent fasting may help reduce insulin resistance, lower fasting blood sugar levels, and decrease the need for diabetes medications in certain cases. Individuals with diabetes must consult with healthcare professionals before implementing fasting into their routine to ensure a safe and personalized approach.

Cellular Repair and Autophagy

Explanation of cellular rejuvenation:

Fasting triggers a process known as autophagy, which is the body’s way of cleaning out damaged cells and regenerating new, healthy ones. During periods of fasting, the lack of incoming nutrients signals cells to undergo this self-repair process. Autophagy not only helps in the removal of dysfunctional cellular components but also promotes the regeneration of new, functional cells, contributing to overall cellular health and longevity.

Role in preventing diseases:

The cellular repair and regeneration facilitated by autophagy through fasting have been linked to a reduced risk of various diseases. Research titled “Fasting: Molecular Mechanisms and Clinical Applications“ suggests that autophagy may play a protective role against conditions such as neurodegenerative diseases, cardiovascular diseases, and certain types of cancers. By promoting cellular health, fasting emerges as a potential strategy for preventing diseases associated with cellular dysfunction.

Mental Clarity and Focus

Cognitive benefits of fasting:

Fasting has been associated with cognitive enhancements, including increased mental clarity and focus. Some proponents of intermittent fasting report heightened alertness and improved concentration during fasting periods. The mechanisms behind these cognitive benefits are not yet fully understood, but it’s believed that the metabolic changes induced by fasting may positively impact brain function and neuroplasticity.

Studies supporting improved mental function:

Several studies have explored the link between fasting and cognitive function, revealing promising results. Fasting-induced ketosis, where the body utilizes ketone bodies for energy, has been associated with improved cognitive performance. Additionally, research indicates that fasting may have neuroprotective effects, potentially reducing the risk of age-related cognitive decline. While more research is needed, the existing studies suggest a positive relationship between fasting and mental well-being.

Potential Risks and Precautions

Nutrient Deficiency

Fasting, if not done mindfully, can lead to nutrient deficiencies. It’s crucial to ensure proper nutrition during fasting periods by focusing on nutrient-dense foods when eating. Including a variety of vegetables, fruits, lean proteins, and whole grains in non-fasting windows helps maintain essential vitamins and minerals.

Supplements and Hydration

To mitigate potential nutrient gaps during fasting, considering supplements may be beneficial. Consult with a healthcare professional to determine if specific vitamins or minerals need supplementation. Adequate hydration is equally essential; drinking water and herbal teas helps maintain overall health and supports the body’s functions during fasting.

Impact on Hormones

Fasting can influence hormonal balance in the body. While some hormonal changes, such as increased human growth hormone (HGH) levels, can be beneficial, it’s important to be aware of potential disruptions. Women, in particular, should consider hormonal fluctuations during fasting and tailor their approach accordingly.

Considerations for Women and Fasting

Women may experience unique hormonal challenges during fasting, especially if they are of reproductive age. It’s advised for women to be mindful of how fasting affects their menstrual cycle and hormonal balance. Pregnant or breastfeeding women should avoid certain fasting practices and consult healthcare professionals for guidance.

Who Shouldn't Fast

While fasting can offer various health benefits, it may not be suitable for everyone. Individuals with certain medical conditions, such as eating disorders, diabetes, or metabolic disorders, should approach fasting with caution and under the supervision of healthcare professionals. Additionally, those with a history of significant weight loss or underweight individuals may need to avoid fasting to prevent further health complications.

Tips for Successful Fasting

Start Slow

Gradual introduction to fasting is a very important point, as you might experience problems with your gut, as it happened to me. Especially in the beginning, breaking a fast might be stressful for your organism, especially your gut, particularly if you have gut problems. Therefore, break a fast slow, with a small meal. 

Stay Hydrated

As important is to stay consistent with your fasting schedule, as your body adjusts to it. Take, for example, flying to another time zone. Your body needs some time to adapt, so I wouldn’t recommend putting your body to this kind of stress often. The timing of when one eats is emphasized as a crucial factor, impacting genes associated with circadian clocks, liver health, bile acid metabolism, energy expenditure, inflammation, and more.


Electrolytes, such as sodium, potassium, and magnesium, play a key role in various physiological processes. Fasting can sometimes lead to electrolyte imbalances, and adequate water intake helps mitigate this. It’s very important to get electrolytes without any sugar in it. 

Why we must Avoid Sugar

Insulin Response

Consuming sugar, especially in the form of refined carbohydrates, causes a rapid spike in blood sugar levels. In response, the pancreas releases insulin to help regulate blood sugar. During fasting, the goal is often to maintain lower and stable insulin levels to promote fat burning and prevent insulin resistance. Consuming sugar can disrupt this process by causing sharp increases in insulin.

Interference with Ketosis

In certain fasting methods, such as intermittent fasting and extended fasting, the body enters a state of ketosis. During ketosis, the body shifts from using glucose as its primary energy source to burning fat. Consuming sugar can halt this process, as the body prioritizes using glucose for energy over fat when sugar is available.

Hunger and Cravings

Foods high in sugar can trigger hunger and cravings. When fasting, managing hunger is crucial to adhere to the fasting period successfully. Consuming sugary foods may lead to a cycle of increased hunger, making it challenging to sustain the fast for the intended duration.

Energy Fluctuations

Sugar provides a quick source of energy, but it is short-lived. During fasting, the goal is often to encourage the body to utilize stored fat for energy, promoting a more sustained and stable energy release. Consuming sugar can lead to rapid energy spikes and crashes, disrupting the desired energy balance during fasting.

Inflammatory Response

Excessive sugar consumption has been linked to inflammation in the body. Fasting is often associated with anti-inflammatory effects, and consuming sugary foods may counteract these benefits. Chronic inflammation is associated with various health issues, and fasting aims to promote a state of improved health and well-being.

Writer's Note

Judging by my personal experience, and all of the research I have read, an optimal feeding window for most people is around 8 hours. We shouldn’t forget, however,  the importance of transitioning gradually when adjusting eating schedules and considering individual factors such as hormone health and personal preferences. Listen to your body, and be consistent. 

I want to leave you with this absolute wealth of knowledge video of Dr. Andrew Huberman, talking for 2 hours and 26 minutes about intermittent fasting. I would really find the time and listen to the video. Happy intermittent fasting everyone, and good luck!

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