Is A 48 Hour Fast Safe

Is A 48 Hour Fast Safe?

Written by Andrew Brewer. ⚕️Reviewed and fact checked by our medical team.

Is A 48 Hour Fast SafeIntermittent fasting has been in practice for centuries because of its incredible health benefits. However, you may be wondering if it is safe to do some of the extended fasts, like a 48-hour fast. Yes, but to be safe, you may want to consult a doctor before you start. Here’s why.

Key Takeaways

  • Intermittent fasting, including extended fasts like a 48-hour fast, can have significant health benefits, but it is important to consult with a doctor before starting to ensure it is safe for you.
  • A 48-hour fast involves refraining from consuming any calories for two days, focusing on drinking water and possibly black coffee or tea. Consuming even a small amount of calories can disrupt the fasting process.
  • During a 48-hour fast, the body transitions into a state called ketosis, where it starts burning stored fat for energy. This process can take around 12 hours to occur, and reaching ketosis is essential for reaping the benefits of intermittent fasting.
  • Prolonged fasts, like a 48-hour fast, can initiate a cellular regeneration process called autophagy, which helps remove damaged cells and promote the growth of new cells. The longer the fast, the more extensive the cellular regeneration.
  • While a 48-hour fast can be beneficial for weight loss and overall health improvement, it is crucial to be cautious and consult a doctor, especially if you have underlying health conditions such as diabetes or are taking medication that requires food intake.

What happens in a 48-hour Fast

A 48-hour fast is when you do not eat or drink anything with caloric value for two days. Instead, you’ll focus on drinking water and occasionally black coffee or tea if you need a little extra energy bump. Select no-calorie sweeteners like Truvia are okay to use during an intermittent fast; however, they could trigger a metabolic response, which could set back your fasting progress.

When you start your fast, your body will be burning through the food you’ve eaten. Once you get through that, it will move to processing the fat stores. This is when your body reaches ketosis, and it can take 12 hours for your body to reach this state. If you accidentally consume calories, no matter how few, they will kick your body out of ketosis, and you’ll need to start the process all over again.

You want to reach ketosis. This is where the magic of intermittent fasting happens, and it is safe to fast until you reach this state.

During prolonged fasts, you will also kickstart a cellular regeneration process called autophagy, which is where your body gets rid of all the bad parts of a cell, cleansing your body of all the toxins to promote new cell growth. The longer you fast, the more new cells your body will generate.

This is why intermittent fasting has been known to improve overall health and reduce the risk of disease. The bad cells are removed from the body, so they will not multiply or infect others.

When Could 48-hour Fasting Be Harmful

Because not eating for 48 hours is a long time, you’ll want to consult with a doctor before undergoing this fast. For example, those with diabetes should not fast without medical guidance as it could cause their blood sugar to drop dangerously low and cause hypoglycemia. Other medicines require you to take them with food, while some medical conditions will actually get worse if you do not eat.

If you are healthy, a 48-hour fast is a fantastic way to lose weight and feel better as your body regenerates and rests in ways that it hasn’t been allowed to do. One way to see if you are ready for a 48-hour fast is to slowly level up.

Begin increasing your fasting intervals until you reach a 48-hour fast. This will help your body become used to fasting without shock. And, when it’s time to eat again, make sure you eat slowly and with small meals at first to prevent discomfort. Consider meal prepping before the fast so you have your meals and snacks on hand to promote healthy decisions.

So, Is a 48-hour Fast Safe?

Yes, 48-hour fasting is safe when done correctly, but if you have any underlying health concerns, you’ll want to consult with a doctor prior to undergoing a fast. This will ensure you don’t have any negative side effects that could potentially harm you in the long run.

As long as you don’t cheat, your body will kick into ketosis and autophagy to help you get the most benefits from this prolonged fast. Remember, the longer you fast, the more benefits you can get, so if you’re looking to overhaul your lifestyle, intermittent fasting is a useful tool to keep in your back pocket.


  • What is a 48-hour fast?

A 48-hour fast is a type of intermittent fasting where you abstain from consuming any calories for two consecutive days. During this time, you can drink water and occasionally have black coffee or tea.

  • How does a 48-hour fast work?

During a 48-hour fast, your body depletes its glycogen stores and eventually enters a state called ketosis. In ketosis, your body starts using stored fat for energy instead of glucose from food. This process can take around 12 hours to occur.

  • Is a 48-hour fast safe for everyone?

While a 48-hour fast can be safe for many people, it is important to consult with a doctor before attempting it, especially if you have underlying health conditions or are taking medications. Certain conditions, such as diabetes, may require medical guidance during fasting.

  • What are the potential benefits of a 48-hour fast?

A 48-hour fast, if done correctly and safely, can provide benefits such as weight loss, cellular regeneration through autophagy, improved insulin sensitivity, and potential reduction in the risk of certain diseases.

  • Can I consume any calories during a 48-hour fast?

No, consuming any calories, even in small amounts, can disrupt the fasting process and prevent your body from reaching ketosis. It is essential to stick to drinking water and avoiding any caloric intake.

  • How can I prepare for a 48-hour fast?

It is recommended to gradually increase fasting intervals and allow your body to adapt to fasting over time. Additionally, consulting with a doctor and considering meal prepping before the fast can help ensure a smooth experience.

  • What should I do when ending a 48-hour fast?

When breaking a 48-hour fast, it is advisable to reintroduce food slowly and start with small, healthy meals to avoid discomfort. Taking time to eat mindfully and make nutritious choices is important for transitioning back to regular eating.

  • Are there any potential risks or side effects of a 48-hour fast?

While a 48-hour fast can be safe for many individuals, it is important to be aware of potential risks. Some people may experience dizziness, low blood sugar, or other adverse effects during fasting. Consulting with a doctor can help identify and mitigate any potential risks.

Andrew Brewer

Andrew Brewer

Andrew Brewer started to give people the guidance that he never received when he was first starting. His goal is to make your goals achievable and to offer you only the best fasting apps that the internet has to offer. You're not on your own - Andrew and the entire family of reviewers at are here with you every step of the way!