The 72 Hour Fast: Discover Key Benefits and Challenges

Hoping to take the fasting game up a notch to discover what benefits might lie? The 72-hour fast is becoming a popular choice now, but before you dive into it, there’s always more to know when it comes to refraining from food and calories. In this article, we explore all there is to know about this longer-than-usual fasting period, whether it’s worth taking the plunge, and how you should prepare yourself for it!

What is a 72 Hour Fast?

A 72-hour fast involves refraining from food and caloric drinks for three consecutive days, usually consuming only water, coffee, or green tea. This extended fasting period prompts the body to enter ketosis, where it switches from burning carbohydrates to burning stored fat for energy. This type of fast is often used for weight loss, detoxification, and improving overall health. Typically, people work up to a 72-hour fast after trying shorter fasting periods, like intermittent fasting or 16–18 hour fasts.

Learn more about intermittent fasting:

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Stages of a 72 Hour Fast

A lot happens to your body during these 72 hours, so it is good to be aware and prepared so that you’re not taken by surprise during this period of time:

Stage 1 (0-4 Hours): Post-Meal Phase

Immediately after eating, your body processes and uses glucose from the meal for energy and cell maintenance. Insulin is released to store excess glucose as glycogen in the liver and muscles. Hunger typically isn’t felt during this time [1].

Stage 2 (4-12 Hours): Glycogen Breakdown

As your body uses up glycogen reserves, it begins breaking them down into glucose for energy. Hunger may set in as glycogen levels decline, especially if your last meal was carbohydrate-rich [2].

Stage 3 (12-48 Hours): Transition to Fat Burning & Ketosis

Once glycogen stores are mostly depleted (around 12-24 hours), the body switches to burning fat for energy with ketosis. Fat is broken down into fatty acids, which the liver converts into ketone bodies. During this phase, autophagy (cellular repair) ramps up, and levels of brain-derived neurotrophic factor (BDNF) increase, promoting brain health [3]. You might feel some fatigue at first, but mental clarity and energy often improve as your brain switches to using ketones.

Stage 4 (48-72 Hours): Full Ketosis

At 48 hours, your body is fully in ketosis, relying entirely on fat for fuel. Autophagy peaks, cleaning out damaged cells. Ketones supply the brain with steady energy, enhancing mental focus and mood [4]. While metabolism slows slightly to conserve energy, fat burning continues, aiding in weight loss and overall cell repair.

Discover answers to other burning questions:

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Benefits of a 72-Hour Fast

There are a wide range of benefits you can reap through this fasting period, and below are a few of them:

• Weight Loss & Metabolism: The 72-hour fast helps you lose weight by ketosis, which burns fat for energy and boosts metabolism by up to 14% [5]. All the while, it’s also improving insulin resistance and sensitivity.
• Cellular Renewal: Activates autophagy, clearing damaged cells and supporting disease prevention and recovery.
• Reduced Inflammation: Lowers chronic inflammation, reducing the risk of heart disease, diabetes, and cancer.
• Cognitive Enhancement: Increases Brain-Derived Neurotrophic Factor (BDNF) [6], improving memory, focus, mood, and potentially protecting against neurodegenerative diseases.
• Mental Clarity & Emotional Balance: Boosts mental clarity and mood, thanks to stable energy from ketones and reduced brain inflammation.

Challenges and Risks of 72-Hour Fasting

Listed below are the factors you should consider before attempting to take up the 72-hour fast:

• Dehydration – Fasting can cause water loss, so hydration and electrolytes are crucial. Drink water and stay hydrated.
• Orthostatic Hypotension – Low blood pressure may cause dizziness; Remember to rise slowly and stay hydrated [7].
• Hyponatremia – Excessive water intake without electrolytes can lead to low sodium, causing nausea and confusion [8].
• Worsening Medical Conditions – Fasting can worsen eating disorders, diabetes, and other health issues.
• Muscle and Weight Loss – Improper fasting can lead to muscle loss and loss of essential nutrients; ensure proper re-feeding, food intake, and exercises for muscle building.
• Dizziness – This may occur due to low blood pressure and blood sugar; Remember to manage hydration and the energy levels of your activity.

Who Should Not Fast

It is always important to consult a physician before taking on a drastic strategy like a 72-hour fasting or water fasting that can affect your body. If you fall under any of the categories below, please refrain from undertaking this fast.

• If you are under 18 or over 65
• Have chronic kidney disease
• Have diabetes (especially type 1)
• Have a history of eating disorders
• Are pregnant or breastfeeding
• Are underweight
• Take medications that affect blood sugar or require food

Tips for Successful Fasting Period

To successfully complete a 72-hour fast, it’s helpful to first try shorter fasts, such as 24 hours, to get your body accustomed to the process. Prior to starting, focus on eating nutrient-dense, low-carb meals and ensure you stay well-hydrated, aiming for at least 3 liters of water per day. You can also drink herbal teas or black coffee, but it’s best to limit caffeine intake. Individuals with certain medical conditions, such as high blood pressure, should consult with their healthcare provider before starting a fast.

During the fast, your body will transition from burning carbohydrates to using fat for energy, which may lead to temporary fatigue and irritability. To make this easier, stick to low-intensity exercises and prioritize rest. Having a support system can help you stay motivated and on track. When you’re ready to break the fast, start with easy-to-digest foods like chicken broth or yogurt, then gradually move to balanced meals. While a 72-hour fast can be beneficial, it’s important to limit such long fasts to a few times a year, and always consult a healthcare provider if you have any underlying health conditions.

Conclusion

With the right mindset and sufficient preparation, the 72-hour fast is a possible feat that includes several health benefits like weight loss, improved insulin sensitivity, and enhanced cognitive performance. But it’s always important to be well-researched on all the factors before diving into it. For more useful tips on diet and exercise, check out the JustFit app!