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48 or 72-Hour Fasting: Which Is Better for Your Health?

There are various types of intermittent fasting—from the easiest 12-hour fasts to more challenging methods; there are many routines to choose from and tailor to your own goals and health concerns.

If you have already tried shorter intermittent fasting styles and feel ready to go one step further, prolonged fasting might be just for you.

While practicing extended fasting, one must abstain from food for one or more full days. But what are the benefits of this eating pattern? And do they differ depending on the length of your fast?

This article explores the differences between the 48 and 72-hour fasting styles, their benefits, and some tips to help you succeed during this phase of your fasting journey.

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48 vs. 72-Hour Fast: What You Should Consider When Choosing

Intermittent fasting and prolonged fasting are both methods of time-restricted eating, but they differ in the duration of the fast. 

When intermittent fasting, you cycle between periods of fasting and eating that can last anywhere from 12 to 36 hours.

Prolonged fasting, on the other hand, refers to abstaining from food for several days or more, and it has traditionally been practiced for spiritual or religious reasons.  Nowadays, more and more people are using it for health-related or weight loss purposes.

The 48 and 72-hour fasts are forms of prolonged fasting.

A 48-hour fast is an extended fast that involves avoiding solid food for two days. While following this eating pattern, you would typically eat your last meal in the evening on the first day and then resume eating at dinner on the third day.

Similarly, a 72-hour fast is a form of extended fasting in which you do not eat for three full days. This fast can be mentally and physically challenging, and should be practiced only by experienced fasters.

In both cases, it is recommended to do an extended fast only 1-2 times a month. Minding the spacing of your fasts is essential for achieving better results.

For a successful fasting experience, regardless of the style you choose, it’s also important that you drink 2-3 liters of water every day and eat balanced, healthy meals on your eating window.

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What To Expect During the 48-Hour Fast

During a 48-hour extended fast, your body goes through several phases that occur within a specific timeline:

After 12 hours of fasting, you enter the first stage, known as ketosis. Ketosis is a metabolic process that occurs when your body’s main source of fuel or stored energy, glucose, runs out. As a result, your body starts burning stored fat resources for fuel and creating ketones by releasing fat into your bloodstream.

During this phase, you may experience symptoms such as fatigue, headaches, nausea, increased thirst or hunger, and bad breath, all common signs of the “keto flu.”

After 18 hours of fasting, your body completely enters the fat-burning mode, using only ketones for energy. You may feel less hungry during this phase as your body adapts to the fasted state.

After 24 hours of fasting, the body finally reaches the state of autophagy. During autophagy, your body reuses old and damaged stem cell parts to create new, healthier ones, functioning as a cellular recycling system.

Autophagy is essential for cells to survive and function properly, and some studies suggest it may help prevent diseases such as type 2 diabetes, Alzheimer’s, and cancer. During this phase, you may experience fatigue and reduced appetite.

But what happens if you continue fasting beyond 48 hours?

What To Expect During the 72-Hour Fast

A 72-hour fast results in a continuation and progression of the phases that started during the first hours of fasting:

After 48 hours, fasting stimulates the secretion of HGH, which is crucial for bone, muscle, and organ growth, as well as regulating body composition, metabolism, and overall physical and mental well-being. This hormone also helps regulate fat distribution in the body and preserve lean muscle and bone mass.

Until you break your fast at the 72-hour mark, your body will continue to burn fat and stimulate cell regeneration. Stem cell regeneration is essential for tissue repair, slowing the effects of aging, protecting against chronic diseases, and recovering from injuries. During this process, stem cells can transform into other types of cells, including new white blood cells, immune cells, fat cells, muscle cells, and nerve cells.

Fasting for 72 hours can increase the stress on the body, which in turn can enhance the process of stem cell regeneration to a greater degree than a fast of a shorter duration.

However, it’s important to note that extended fasting should only be attempted under medical supervision, and it may not be suitable for everyone. Always listen to your body and stop your fast if you experience severe symptoms or discomfort.

48 vs. 72-Hour Fast: Benefits

The two extended fasting types are quite similar to one another. However, they can offer different health benefits.

48-hour fast benefits

The benefits of fasting for 48 hours include:

72-hour fast benefits

Fasting for 72 hours or more can provide additional health benefits, including:

  • Improved mental clarity — the energy that was previously used for digesting food is now used by the brain, promoting mental clarity. Furthermore, fasting reduces the number of toxic materials in the bloodstream and lymphatic system, which can improve brain health.
  • Can promote heart health — fasting for 72 hours can help lower blood pressure, reduce cholesterol levels, and improve heart health markers. This can benefit your heart and help prevent cardiovascular diseases.
  • Increased longevity — fasting for 72 hours promotes stem cell regeneration and  increases human growth hormone (HGH).

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48 and 72-Hour Fast: Risks and Drawbacks

Although both of these extended fasts show great weight loss and health-related benefits, they also do have some drawbacks that you might want to consider. These include:

  • Severe hunger — a decrease in leptin levels during fasting may cause severe hunger, but this should go away as the body adapts to the fasting conditions.
  • Dizziness and exhaustion — caused by low blood sugar levels that last for an extended period of time.
  • Dehydration — prolonged fasting can reduce urine production and sweat, leading to dehydration. Additionally, the body may lose electrolytes, which are important for maintaining hydration.
  • Insomnia — prolonged fasting might increase stress hormones such as cortisol and changes in the body’s circadian rhythm, which can cause insomnia. Additionally, it might be hard to fall or stay asleep if you’re feeling extreme hunger.

6 Tips To Minimise the Side Effects of Prolonged Fasting

Prolonged fasting can bring some side effects. Luckily, there are ways to mitigate them.

1. Get used to your routine slowly

To give your body time to adjust to changes and reduce the likelihood of side effects, it’s recommended to start with shorter intermittent fasting styles before attempting extended fasts. For beginners, a 12/12 intermittent fasting routine can be a good starting point. Once you get used to shorter methods, you can safely and gradually work your way up to longer fasts.

If you’re unsure where to start, a personalized fasting app like DoFasting can be helpful. By filling out a questionnaire about your goals and preferences, you can receive guidance and a customized fasting routine. The app also includes a fasting timer to help you keep track of your progress.

2. Stay hydrated during the fasting period

Dehydration can cause a number of adverse side effects, like dizziness, exhaustion, or headaches. Moreover, extended fasts can cause changes in the body’s metabolism and hormone levels that contribute to dehydration.

Therefore, drinking water or other zero-calorie fluids such as green tea is vital to keep yourself hydrated and help proper body functioning. Drinking will also help you reduce feelings of hunger since fluids can fill the stomach.

3. Replenish lost electrolytes

When fasting, it’s possible to lose electrolytes through sweat and urine, which can impact proper hydration and body function. Sodium, potassium, and magnesium are important electrolytes that need to be replenished.

To do so, it’s recommended to consume electrolyte-rich foods and drinks during your eating windows, like bone broth, coconut water, spinach, lentils, and sunflower seeds. You can also consume sports drinks high in electrolytes.

4. We Break your fast with a nutritious meal

Fasting for an extended period of time can cause your body to lose essential vitamins, minerals, and nutrients, which is why breaking your fast with unhealthy, low-fiber foods can cause blood sugar spikes and crashes.

To help your body adjust to your normal routine again, it’s recommended to break your fast with a nutritious meal, including healthy fats, proteins, fiber, and carbohydrates. 

You can plan what you eat ahead of time by using the DoFasting app, which includes thousands of healthy recipes to boost your fasting experience.

5. Keep yourself busy

Staying occupied with activities that require concentration can help you take your mind off hunger and prevent distractions caused by food around you.

To reduce hunger pangs, engage in light exercise, go for a walk, or try meditation. Hobbies like reading, painting, or anything that you enjoy can also help lower your hunger levels.

6. Know your limits and listen to your body

It’s important to understand that finding what works best for you may take some time. If you are attempting an extended fast for the first time, listen to your body and do not push yourself too hard. Don’t feel discouraged if you can’t stick to the routine on your first try.

If you experience any discomfort, complications, or adverse side effects during an extended fast, it’s best to break the fast. This may indicate that longer fasts may not be suitable for you.

Who Should Refrain From Prolonged Fasting?

Although fasting can be beneficial for many people, it may not be appropriate for everyone. Certain groups of people should refrain from fasting, including:

  • Pregnant or breastfeeding individuals — as they have higher nutritional needs.
  • Children under 18 — children in developing age have increased metabolic needs and require more calories for growth and development.
  • People with type 1 diabetes — patients with this condition are at higher risk of experiencing hypoglycemia when fasting.
  • Underweight people — as they could lose even more weight.
  • People with a history of eating disorders — as fasting might trigger the symptoms of disordered eating.
  • People who are taking certain medications — these can be blood pressure medications, blood thinners, or insulin.

If you fall into one of these categories or have any health concerns, it’s recommended that you contact your doctor before starting prolonged fasting.

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48 vs. 72-Hour Fasting: Final Considerations

The 48 and 72-hour fasts are two forms of extended fasting in which one abstains from food for either two or three full days.

These lengthy fasts can provide various health benefits, including decreased inflammation, cellular repair, improved immune system, reduced insulin resistance, and weight loss.

However, fasting for such long periods may have certain adverse side effects that you could prevent by remaining hydrated, eating nutritious meals throughout your eating window, and listening to your body.

If you are not familiar with advanced fasting methods like these, it’s advisable to try with shorter fasting styles first. Consult with a medical professional if you have any health concerns.


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This is an evidence-based article that includes scientific citations. DoFasting’s professional writers and editors prepared the content, which a team of medical experts verified to be accurate.

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