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Not Eating: Exploring the Consequences and Dangers of Prolonged Fasting

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Fasting has become a popular trend in recent years. Many people use it as a way to lose weight, detoxify the body, and improve their health. However, not all forms of fasting are healthy, and prolonged fasting can have serious consequences for the body. In this article, we will explore the topic of prolonged fasting and the dangers associated with it. We will delve into the science behind fasting and its effects on the body, as well as the potential risks of prolonged fasting. By the end of this article, you will have a better understanding of the consequences of not eating and why it's essential to seek medical advice before attempting any prolonged fasts.

Benefits and Risks of Fasting

Fasting has become a popular trend amongst health enthusiasts, and it has been claimed to offer numerous benefits that include weight loss, improved metabolism, and even a longer lifespan. However, proponents of fasting also highlight the risks that come with it. It is essential to understand both the benefits and risks before trying prolonged fasting. Let's delve deeper into the advantages and dangers of fasting.

Benefits of Fasting

Weight loss is one of the most significant benefits of fasting. When you fast, your body starts to burn stored fat cells for energy, resulting in weight loss. This process happens because the body is deprived of glucose, forcing it to utilize its fat stores for energy. Fasting also helps to boost metabolism, thereby increasing the rate at which the body burns calories.

Additionally, fasting has been linked to various health benefits, such as improved immune function and reduced inflammation. Some studies suggest that fasting can also help in reducing the risk of chronic diseases like heart disease and type 2 diabetes. Fasting also helps to keep the body in a state of autophagy, which helps to eliminate damaged cells in the body.

Risks of Fasting

Like with any other diet, fasting can result in significant health risks. One of the most common risks associated with fasting is muscle loss. The body requires amino acids, which are obtained from the breakdown of proteins to build and repair muscles. During an extended fast, the body may turn to break down muscle tissue for energy. Additionally, fasting can lead to dehydration, which can cause headaches, dizziness, and fatigue.

Fasting can also cause a drop in blood sugar levels, which can lead to hypoglycemia. People with diabetes, in particular, should be cautious when fasting as it can lead to serious complications. It is essential to note that prolonged fasting can also result in malnutrition, which could have adverse effects on the body.

The Science Behind Prolonged Fasting

Fasting is known to have several health benefits, but it’s essential to know the science behind it. When the body does not receive the energy it needs from food, it starts using up stored energy from fat cells. After the body utilizes all the stored energy, it starts to use up glucose reserves from the liver. This is when the body enters the state of ketosis, where it starts using fat as its primary energy source.

During prolonged fasting, the body undergoes several changes. The levels of insulin, the hormone that regulates blood sugar levels, decrease dramatically. Lower insulin levels signal your body to burn stored glucose. After exhausting stored glucose, your metabolism switches to using ketones, which are natural compounds produced in response to low glucose levels.

Prolonged fasting has also been linked to increased levels of human growth hormone (HGH), which plays a critical role in growth, metabolism, and body composition. HGH fuels growth in children and adolescents and helps maintain lean muscle mass and bone density in adults. The increased production of HGH during fasting may be responsible for some of the health benefits attributed to fasting, such as improved metabolism and weight loss.

In addition to the changes in insulin and HGH levels, fasting also affects other hormones in the body. Ghrelin, known as the hunger hormone, is produced in the stomach and signals to the brain that it’s time to eat. Interestingly, ghrelin levels increase during fasting, which can cause hunger pangs. However, ghrelin levels drop after several days of fasting, which can lead to a decrease in appetite.

The Consequences of Prolonged Fasting

Prolonged fasting can have severe physical and psychological consequences on the individual. While some people may experience short-term benefits, prolonged fasting can lead to long-term consequences that can be harmful to one's health.

One of the most common physical consequences of prolonged fasting is dizziness and weakness, which can lead to fainting and other injuries. Malnutrition is also a common consequence of prolonged fasting. It can lead to deficiencies in essential vitamins and minerals, which can cause long-term health problems such as stunted growth, weakened immune system, and organ failure.

In addition to physical consequences, prolonged fasting can also cause psychological consequences such as anxiety, depression, and irritability. Many people who fast for long periods may experience mood swings, difficulty concentrating, and sleep disturbances. While some people may feel a sense of euphoria during the fast, these feelings are often short-lived and quickly replaced by negative emotions.

It is crucial to understand the consequences of prolonged fasting before embarking on such a dietary regime. While some may believe that prolonged fasting is an excellent way to lose weight quickly, the long-term consequences can be severe. It is always advisable to speak with a healthcare professional before deciding to fast for an extended period. A healthcare professional can advise on a safe and healthy approach to achieve one's desired weight loss goals without risking harm to one's health.

Dangers of Prolonged Fasting

Prolonged fasting, defined as abstaining from food for more than 48-72 hours, can have serious consequences on the human body, including life-threatening risks. While some people may believe that fasting is a quick and effective way to lose weight or "detox" the body, the potential dangers of prolonged fasting should not be ignored.

One of the most critical risks associated with prolonged fasting is cardiac arrhythmia. When the body experiences a lack of essential nutrients and electrolytes, the heart's electrical system can become erratic, leading to an irregular heartbeat. Prolonged fasting can also lead to hypotension or a drop in blood pressure, which can cause dizziness or fainting.

Organ failure is also a serious danger of prolonged fasting. Without adequate nutrient intake, the body may begin to break down its own muscles and organs for energy, leading to a decrease in organ function. Kidney function, in particular, is at risk during prolonged fasting, as the kidneys require adequate hydration to process toxins and waste.

It's crucial to recognize that prolonged fasting requires medical supervision. Doctors and medical professionals can help ensure that an individual is healthy enough to fast, monitor any potential complications, and provide guidance for breaking a fast safely.


In conclusion, we have explored the consequences and dangers of prolonged fasting. Fasting has become a popular trend, and while it has several benefits, there are risks associated with it that cannot be overlooked. We discussed how fasting affects the body and looked at the physical and psychological consequences of prolonged fasting.

Prolonged fasting poses life-threatening risks such as cardiac arrhythmia and organ failure. It is essential to seek medical supervision during prolonged fasting and not attempt it without expert advice.

The main takeaway is that although fasting can have positive effects on the body, it can also be dangerous if not done correctly. It is important to approach fasting with caution and make sure to seek medical advice before attempting prolonged fasting.

Frequently Asked Questions

  1. What are the benefits of fasting?

    There are many benefits of fasting including weight loss, improved metabolism, and even improved cognitive function.

  2. What are the risks associated with fasting?

    Risks associated with fasting include muscle loss, dehydration, and even malnutrition if not done properly.

  3. What happens to the body during prolonged fasting?

    During prolonged fasting, the body goes into a state of ketosis where it begins to use stored fat as energy instead of glucose. Hormones are also affected as insulin levels decrease.

  4. What are the physical and psychological consequences of prolonged fasting?

    Physical consequences of prolonged fasting include dizziness, weakness, and malnutrition. Psychological consequences may include anxiety, depression, and irritability.

  5. Is prolonged fasting dangerous?

    Yes, prolonged fasting can be dangerous if not done properly. Life-threatening risks include cardiac arrhythmia and organ failure, which is why medical supervision is important.

William H. McDaniel, MD

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School.

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