Take a 1-min quiz to get a Your Fasting Plan Male Female

36-Hour Fast for Weight Loss: Effectiveness, Safety, and Benefits

Fasting for 36 hours, aka the Monk Fast, may be an ideal weight loss option for some, but not for others. Named after the monks who practice this type of fast for spiritual purposes, it involves abstaining from food and calorie-containing beverages for a full 36 hours. 

Theoretically, this fasting method can lead to a significant overall calorie deficit, resulting in weight loss. However, as with any other dietary approach, it has its own set of potential benefits and drawbacks.

So, if you’re wondering whether a 36-hour fast is effective, safe, and beneficial for weight loss,  keep reading to find out.

How Much Weight Can You Lose Doing a 36-Hour Fast?

A single 36-hour fast may lead to a weight loss of 1-2 pounds (0.5-1 kg) on average, which will be mostly water. This number may vary depending on your starting weight and body composition. You may lose more weight if you’re able to consistently do this fast multiple times over a period of weeks or months (15).

During a 36-hour fast, you’ll be consuming zero calories, which means your body will need to rely on its stored energy. At first, it will use up its glycogen (carbohydrate) stores, which will cause the release of a significant amount of water that is stored together with the glycogen. 

Once glycogen is depleted, your body will turn to its stores of protein (muscles) and fat. 

There is limited research on the effectiveness of a 36-hour fast specifically for weight loss. Some studies have found that longer periods of fasting can lead to greater weight loss, but we know that weight loss is not solely dependent on the length of time between meals.

Weight loss ultimately comes down to creating a calorie deficit, consistently over time. For some, a 36-hour fast every so often is the best way of doing this. It may help reset their eating habits and decrease overall calorie intake. 

However, for others, this approach may not be sustainable or suitable. Beginners who have never fasted before may find it challenging to go without food for such an extended period, which can lead to overeating and potential weight gain once the fast is broken.


Weight loss is also dependent on food quality. Just because you’re not eating for 36 hours doesn’t mean it’s an excuse to binge on high-calorie foods during the feeding window.  

We know that food quality has ripple effects on our weight and overall health. So, even if a 36-hour fast may help with weight loss in the short term, it’s important to prioritize nutrient-dense foods during the feeding window for long-term success (9).

Lastly, the effectiveness of a 36-hour fast for weight loss also depends on an individual’s metabolism and activity levels. Someone with a slower metabolism or lower physical activity levels may not see the same weight loss results as someone with a faster metabolism or higher physical activity levels (8).

So, is a 36-hour fast good for weight loss? In some cases, yes, it can be effective for weight loss if it helps a person eat less overall for an extended period of time. Beyond 36-hour fast success stories, you should consider individual factors and make sure it suits your overall lifestyle and goals.

BetterMe is your fast-track ticket to a long-lasting weight loss! Tailor your fitness journey and maximize your results with just a couple of swipes!

What Happens to Your Body After 36 Hours of Fasting?

Hormonal, metabolic, and cellular changes occur in your body when you fast, and these changes can have an impact on weight loss. During a 36-hour fast, the following may happen to your body:

  • Insulin levels drop: By not consuming any food or calories, insulin (the hormone that is responsible for regulating blood sugar) levels decrease. This helps your body switch from using glucose as its primary source of energy to eventually using more stored fat for energy (3).
  • Autophagy may increase: Autophagy is the process through which your body breaks down and recycles old or damaged cells. During a fast, autophagy is believed to increase, leading to potential benefits such as improved cellular function and decreased inflammation (13).
  • Ketosis may occur: After 36 hours of fasting, the body’s stored glucose may be largely depleted, and it starts to break down more fat for energy. This can lead to ketosis where the body produces ketones as an alternative source of fuel. Some people claim to experience the physical and mental benefits associated with ketosis, such as increased energy and focus, although this is subjective (7).
  • Metabolic rate may decrease: While fasting can lead to an initial increase in metabolism due to the stress response, after 36 hours without food, the body starts conserving energy by decreasing its metabolic rate. This is why it’s important to break a fast with nutrient-dense foods that may help avoid any potential negative effects on metabolism (14).

These changes in the body during a 36-hour fast may contribute to weight loss and other potential health benefits.

It should be noted that a great deal of research on fasting has been conducted on animal models or small-scale studies, so more research is required to fully understand the effects on humans. You should always talk to your healthcare provider before you attempt any fast or fasting regimen.

Is Fasting for 36 Hours Good for You?

A 36-hour fast twice a week or even just once a week may provide some health benefits. Research specifically looking at a 36-hour fast is limited, but studies on other intermittent fasting methods have suggested potential benefits including:

Improve Insulin Sensitivity

Insulin sensitivity refers to how well your body responds to insulin, a hormone that regulates blood sugar levels. Poor insulin sensitivity can lead to health issues such as type 2 diabetes and metabolic syndrome. Some studies have found intermittent fasting to improve insulin sensitivity, which can potentially reduce the risk of developing these conditions (3).

Improved Markers of Metabolic Health

Metabolic health refers to the state of your body’s metabolism, including blood sugar levels, cholesterol levels, and blood pressure. Research has suggested that intermittent fasting methods can improve some of these markers of metabolic health, potentially reducing the risk of chronic diseases (14).

Reduced Inflammation

Inflammation is a natural response in the body, but it can become harmful when it becomes chronic or uncontrolled. Some studies have suggested that intermittent fasting can potentially reduce inflammation levels in the body, which may have a positive impact on overall health (10). 

Increase Autophagy

Autophagy is the body’s natural process of breaking down old or damaged cells and recycling their components for energy. This process is responsible for the removal of damaged cell components and misfolded proteins, and it can also improve cellular functioning. Research has suggested that intermittent fasting may increase autophagy, which can lead to potential health benefits (13).

Weight Loss

As previously mentioned, a 36-hour fast can promote weight loss by creating an overall calorie deficit. This helps reduce body fat and may also have positive effects on overall health, as excess weight is linked to various chronic diseases (6).

Improved Cardiovascular Health

Some studies have found intermittent fasting to help reduce blood pressure, inflammation, and cholesterol levels, all of which are risk factors for heart disease (5).


By improving insulin sensitivity, reducing inflammation, and increasing autophagy, intermittent fasting may also have anti-aging effects and potentially increase lifespan, although there is a lack of research in humans in this area (4).

Read more: Why Stop Eating Oatmeal – A Breakfast Revolution


Safety Considerations

While there may be potential benefits to a 36-hour fast for weight loss and overall health, it’s important to consider safety precautions before you embark on this or any type of fast. Here are some things you should keep in mind:

Talk to Your Doctor

If you have any underlying health conditions or are taking medication, it’s important to talk to your doctor before you start a 36-hour fast. They can provide personalized advice and ensure that fasting will not interfere with your health.

Not everyone can fast safely and the following groups of people should avoid fasting altogether:

  • Pregnant or breastfeeding women
  • Children and adolescents
  • Individuals with a history of disordered eating
  • Individuals with low body weight
  • Those with a history of blood sugar issues, such as diabetes
  • Individuals with underlying health conditions or who are taking medication
  • Older adults (may need a modified fasting approach)

Ease into It

If you’re new to fasting, it may be helpful to ease into it by starting with shorter fasting periods and gradually increasing the duration. This will give your body time to adapt and help prevent any adverse effects. A common approach is to start with a 12-hour fast and slowly increase it by one or two hours until you ultimately reach your desired fasting duration. You’ll know you’re ready for a 36-hour fast when you feel comfortable and have enough energy to go about your day.

Stay Hydrated

During the 36-hour fast, you must hydrate well. Dehydration is a potential side effect of fasting, as you’re not consuming any food during this time. Make sure to drink plenty of water – at least 8 cups a day – and consider electrolyte supplementation if necessary. 

This will also help reduce hunger pangs and keep your energy levels up. You’re allowed to drink zero-calorie beverages such as sugarless black coffee, tea, and electrolyte-infused water.

Listen to Your Body

You should never push yourself beyond what feels comfortable during a 36-hour fast. Some discomfort is expected (such as hunger and fatigue), but if you experience any severe symptoms such as dizziness, nausea, or extreme weakness, it’s important to break the fast and eat a small meal.

Break the Fast Carefully

Breaking a 36-hour fast should be done gradually. Start with a light meal that includes nutrient-dense foods such as vegetables, protein, and healthy fats. Avoid overeating or binging on high-calorie foods, as this can lead to digestive issues and weight gain. 

Once the fast is broken, continue to prioritize nutrient-dense foods during the feeding window for optimal health benefits.

If you’ve mustered up the courage to crush your weight loss goal, let Betterme take the sting out of this demanding process. Our app will help you restructure your habits, remold your life and crank up your fitness results!

Can I Exercise on a 36-Hour Fast?

During the fasting period, engaging in low-intensity exercises such as walking or yoga can be beneficial and help reduce hunger pangs. It may also help stimulate autophagy and improve insulin sensitivity (11). However, high-intensity exercises should be avoided during a fast, as they require more energy and may cause fatigue or dizziness.

The best approach to exercise during a 36-hour fast is to listen to your body and do what feels comfortable. If you’re new to exercising while fasting, it may be helpful to start with low-intensity activities and gradually increase the intensity as your body adapts.



  • Can I drink coffee on a 36-hour fast?

Yes, you can drink black coffee during a 36-hour fast, as long as it’s sugarless and calorie-free. Some people find that it helps reduce hunger pangs and can provide an energy boost during the fasting period (11). However, you should be mindful of any potential side effects such as increased heart rate or anxiety. If you’re particularly sensitive to caffeine, it may be best to drink decaffeinated coffee or opt for other zero-calorie beverages such as tea or electrolyte-infused water.

  • How often should you do a 36-hour fast?

How often you should do a 36-hour fast can vary depending on individual health and goals. 

If you’re in good health and have built your tolerance over time, you may be able to do a 36-hour fast as often as once or twice per week, if desired. It’s important to find a frequency that works for you and doesn’t cause any adverse effects.

  • Why am I not hungry after a 36-hour fast?

During a 36-hour fast, the body shifts into a state of ketosis, using stored fat for energy instead of glucose from food. Some people find this can suppress their appetite and reduce hunger pangs. 

  • How long should I fast to lose belly fat?

Some people have found that fasting for 36 hours once or twice a week helps promote fat loss and reduce belly fat. However, individual experiences will vary. It’s also essential to prioritize nutrient-dense foods and regular exercise during the feeding window for optimal results. 

It’s important to remember that spot reduction is not possible and fat loss will occur evenly throughout the body. Therefore, a combination of reduced overall calorie intake, healthy eating, and exercise is the best approach for losing belly fat.

The Bottom Line

Fasting for 36 hours may be an effective weight loss option for some individuals. It may also have potential health benefits, such as improving insulin sensitivity and certain markers of metabolic health. 

However, it’s important to consider individual factors, prioritize food quality during the feeding window, and consult a doctor before you start this type of fast. While fasting can be a helpful tool for achieving your weight loss goals, it shouldn’t be used as a sole means of weight loss and should be incorporated into a healthy lifestyle. 


This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. Effects of Intermittent Fasting on Brain Metabolism (2022,nih.gov)
  2. Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. (1988,nih.gov)
  3. Intermittent Fasting and Insulin Resistance: Benefits Beyond Weight Loss (2022,jeffersonhealth.org)
  4. Intermittent fasting and longevity: From animal models to implication for humans (2024,sciencedirect.com)
  5. Intermittent Fasting: A Heart Healthy Dietary Pattern? (2020,nih.gov)
  6. Intermittent fasting and weight loss
  7. Low-carb diets, fasting and euphoria: Is there a link between ketosis and gamma-hydroxybutyrate (2007,nih.gov)
  8. Metabolism and weight loss: How you burn calories (2022,nih.gov)
  9. Optimal Diet Strategies for Weight Loss and Weight Loss Maintenance (2021,nih.gov)
  10. Role of Intermittent Fasting on Improving Health and Reducing Diseases (2014,nih.gov)
  11. The effect of black coffee on fasting metabolic markers and an abbreviated fat tolerance test (2021,nih.gov)
  12. The Effects of Exercise on Appetite-Regulating Hormone Concentrations over a 36-h Fast in Healthy Young Adults: A Randomized Crossover Study (2023,nih.gov)
  13. The effect of fasting or calorie restriction on autophagy induction: A review of the literature (2018,nih.gov)
  14. The Effect of Fasting on Human Metabolism and Psychological Health (2022,nih.gov)
  15. Twice-Weekly 36-Hour Intermittent Fasting Practice Attenuates Hunger, Quadruples ß-Hydroxybutyrate, and Maintains Weight Loss: A Case Report (2024,nih.gov)


150 million people
have chosen BetterMe

I like very much this application

In one app you have timing for fasting, workouts and calorie counter. Very comfortable to use. And additional service with a meal plan is very useful! I love the recipes it has! They are amazing!...

Fasting program

Gary S.
This fasting program is excellent! Well designed and easy to use. You will get great results.

Such an awesome

Aaron K.
Such an awesome app! been using it for a few months now and I am really happy with the results as the app is incredibly versatile especially if you prefer to work out at home...