If you’re contemplating a 72-hour fast, the question that may come to your mind is whether it’s good or beneficial to your health. Of course, you shouldn’t just jump into fasting before understanding the potential benefits. So, is fasting for 3 days good for you?
That is the question we plan to discuss in this article. 3-day fasting has gained a great deal of popularity recently, perhaps due to the claims of potential benefits that come with it and also the simplicity of implementing it. But first, let’s talk about why people claim it is beneficial.
Is Fasting for 3 Days Safe for Your Health?
When approached with caution, fasting for 3 days can be safe for most healthy adults. Whether it’s safe or not depends on the health of the individual, in addition to other individual factors. The body has the ability to go for a certain period without food if you don’t have any health or metabolic conditions, aren’t underweight, and aren’t pregnant or breastfeeding. It’s also important to know that fasting for 3 days may come with some risks, even for healthy people. To reduce some of these risks, such as dehydration, you need to drink plenty of water to help keep you hydrated during the fasting period.
Therefore, if you’re an adult in good health, this type of fasting could be safe for you. However, if you have diabetes, are pregnant, breastfeeding, or have any other medical condition, you should consult a healthcare professional to understand whether it’s safe for you or not.
What Do 3 Days of Fasting Do to the Body?
When you start fasting, your body undergoes some metabolic adaptations. One of the first things that happens is that the body uses glycogen that is stored in the liver and in the muscles for energy. Glycogen is stored carbohydrates that can be used for energy in the absence of enough carbohydrates from food. When the glycogen stores get depleted, the body enters the state of ketosis where it starts to break down fat to release energy. A 3-day fast may also lead to the following changes in the body:
- Might Improve Insulin Sensitivity
It has been suggested that intermittent fasting improves insulin sensitivity and blood pressure (2). It may also be helpful in improving glucose and lipid metabolism. These metabolic improvements are probably related to weight loss, which fasting may help with by decreasing your overall energy intake. Weight loss and metabolic improvements take time though, so a single 3-day fast isn’t likely to make much of a difference. Other forms of fasting that are more intermittent (such as time-restricted feeding, 5:2, and alternate-day fasting) can be done over a longer period of time and are more likely to lead to these benefits.
- May Improve Digestive Health
It has also been suggested that fasting alters the gut microbiome. It may increase the bacteria that are associated with short-chain fatty acid production and improve overall metabolic health (3). The gut microbiome is a key factor in digestive and overall health.
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- Promotes Ketogenesis
As the body depletes the glycogen stores, it resorts to burning fat for energy. The ketogenesis process produces ketones from fat that serve as an energy alternative to the body. Some people find this desirable for various reasons.
- Weight Loss
Fasting can make the body utilize stored fats for energy as it happens in the process of ketosis. After the body has used up its glycogen stores, which usually happens within 24 hours, the body starts to break down fats that are stored in the body for energy and this can lead to loss in weight. However, sustainable weight loss takes a long time, and a single 3-day fast isn’t likely to move the needle much. Long-term healthy, balanced diets are a much more reliable strategy for weight loss.
Read more: The Ultimate Low-Carb Intermittent Fasting Meal Plan: Your Guide To Fat Loss Without Starving
How Long Can I Fast Without Losing Muscle?
Any time you go without enough food, your body uses stored glycogen and fat for energy and also breaks down some muscle tissue for the protein it needs to function. This may actually happen earlier in a fast, until your body starts to spare protein as much as it can (5). Any time you fast, if you lose weight, it’s likely to be a combination of water, fat, and muscle. There are some other factors that may influence muscle loss while fasting, including:
- Protein intake – if you’re eating adequate amounts of protein during your eating window, it should be helpful for preserving muscle mass during the fasting period.
- Resistance training – engaging in resistance exercise (during your eating window) is important for countering muscle loss as it promotes protein synthesis.
- Individual factors – other factors such as sex, age, genetics, and overall health condition may also dictate how your body responds to fasting and the potential for muscle loss.
How Long Do You Need to Fast to Get Rid of Bad Cells?
Getting rid of bad cells and cell components in the body (autophagy) is believed to be upregulated from as little as 12 to 16 hours of fasting. Longer fasts probably induce more significant autophagy (1). However, there’s a lack of definitive evidence about the effects of fasting on autophagy in humans. In addition, while autophagy is believed to have benefits, excessive autophagy may be detrimental.
What Happens to Your Cells When You Fast for 3 Days?
When you fast for 3 days, your body probably increases autophagy – a process of cellular repair where old and damaged cells and cell components are broken down and recycled. However, as previously mentioned, there is a lack of clear evidence on the effects of fasting on autophagy in humans.
Read more: Intermittent Fasting Vegan Diet: What It Entails, Rules To Follow & More
How Can I Safely Do a 3-Day Fast?
Whether you’re a beginner or just want some tips on how to safely conduct your 3-day fast, it’s important to understand that this isn’t a short period and this is how to safely undertake it:
- Talk to Your Healthcare Provider
Before starting any type of fast or fasting regimen, always talk to your healthcare provider first. They can help you determine whether you should do it and how to do it safely, according to your individual health needs and preferences.
- Start Slowly
When starting, incorporate some shorter fasts as in intermittent fasting where you fast for a few hours, then eat during the eating window hours. This will help you understand your body and learn how it responds to fasting, and you can work your way up to longer fasting windows.
- Choose a Suitable Type of Fast
The type of fast you choose is also important. For example, if you’re a beginner, you probably shouldn’t do a water-only or extended fasting period as you need to first understand how your body responds and shorter fasts or fasts that allow a limited number of calories would be more appropriate to start with. Dive deeper into the 16:8 fasting diet plan with our dedicated article.
- Hydrate Properly
It’s important to take plenty of water as it helps maintain overall health and well-being. It also helps prevent dehydration-related issues such as fatigue, dizziness, and headaches while fasting.
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- Limit Physical Activities
While fasting, particularly if you’re doing more than 24 hours, you need to limit certain physical activities such as high-intensity exercises as they require a lot of energy. However, you may include some light physical activity that doesn’t require as much energy.
- Listen to Your Body
While fasting, it’s important to listen to your body and stop or limit any exercises you’re doing if you feel dizzy or weak.
- Can You Exercise While Fasting?
Yes, you can exercise while fasting. However, you need to ensure that your exercises are light to moderate, depending on how you feel and the length of your fast. Therefore, you can engage in simple exercises such as walking or stretching. However, it’s important to note that intense workouts or exercises may not be suitable as the body is in an energy-conserving state.
The lighter exercises you do are helpful in fat oxidation and also maintaining a certain level of physical activity that doesn’t cause fatigue or dehydration. In addition, while exercising, you should listen to your body for any signals and stop the exercises if you feel weak or dizzy.
The number of days that is safe for fasting depends on individual needs, goals, and health conditions. While a 3-day fast is safe for some, it may not be safe for individuals with health issues or metabolic conditions. Always talk to your healthcare provider as they can help you assess your individual situation and determine whether you should fast and how to fast safely. A 3-day fast may be good for gut health in some ways. It allows the digestive system to rest for a short while and may promote the growth of beneficial bacteria that are good for the gut (3). However, individual experiences may vary. Fasting may temporarily affect your metabolism and your metabolic rate could either increase or decrease, depending on the type of fasting and also the duration among other factors. Fasting also causes your metabolism to temporarily shift to alternate sources of energy. It has been suggested that fasting helps suppress inflammation, modulates immune responses, and enhances immune memory (4). Fasting may also stimulate the production of new immune cells and the breakdown of damaged and old immune cells. However, it’s not possible to say exactly what effect a single 3-day fast will have on an individual’s immune system. Frequently Asked Questions
How many days of fasting Is safe?
Is a 3-day fast good for gut health?
Does fasting for 3 days reset your metabolism?
Can a 3-day fast reset your immune system?
The Bottom Line
As we’ve learned, fasting can cause a number of changes in your body. It’s thought to be beneficial for improving insulin sensitivity and blood pressure and also in weight loss, among other benefits. While it comes with some potential advantages, it’s important to approach it with caution.
A 3-day fast may be beneficial if it’s suitable for your body and individual needs. However, if you have other health conditions such as diabetes or you’re pregnant or breastfeeding, among other conditions, then you should consult a healthcare professional to get personalized advice. However, if you’re an otherwise healthy adult, implementing a 3-day fast safely may help you achieve some benefits. In addition, you must remember to keep hydrated by drinking plenty of water during the fast.
DISCLAIMER:
This article is intended for general informational purposes only and does not serve to address individual circumstances. It is not a substitute for professional advice or help and should not be relied on for making any kind of decision-making. Any action taken as a direct or indirect result of the information in this article is entirely at your own risk and is your sole responsibility.
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SOURCES:
- Autophagy Fasting: What You Need to Know Before Starting (2024, lifemd.com).
- Effect of Intermittent Fasting Diet on Glucose and Lipid Metabolism and Insulin Resistance in Patients with Impaired Glucose and Lipid Metabolism: A Systematic Review and Meta-Analysis (2022, pmc.ncbi.nlm.nih.gov).
- Fasting alters the gut microbiome reducing blood pressure and body weight in metabolic syndrome patients (2021, nature.com).
- Fasting and Immune Health (2024, ifm.org).
- Is muscle and protein loss relevant in long‐term fasting in healthy men? A prospective trial on physiological adaptations (2021, pmc.ncbi.nlm.nih.gov)
