How Long Can You Go Without Food?

How long can the human body survive without food? Since food is a crucial source of survival, understanding the limits of fasting or any form of diet is intriguing. Our understanding of these topics primarily comes from real-life incidents rather than controlled experiments, as testing such limits could be fatal. Observations from cases of starvation or prolonged fasting have provided insights into the body’s endurance.

However, survival time on a prolonged fast or restrictive diet can vary based on several factors, including the individual’s health before starvation. To gain a deeper understanding of the body’s response in these situations, we explore this question with insights from weight loss and wellness expert Melissa Mitri. Read on to find out more!

What Happens When You Don’t Have Food?

Food is our primary energy source, so when we stop eating and can no longer convert food into glucose (i.e. blood sugar), the body starts to adapt. Glucose is crucial for energy, so when it’s scarce, the body seeks alternative fuel sources.

So what happens when you don’t have food? Initially, the body uses glucose stored in the liver and muscles.

As the body uses up its glycogen stores, it then turns to fat reserves for energy. During this phase, you may experience symptoms such as weight loss, fatigue, and dizziness.

Burning through fat reserves can take several weeks, depending on individual body composition. Once fat stores are exhausted, the body begins to break down muscle tissue for energy. At this stage, the final phase of starvation sets in, leading to muscle deterioration and a severe impact on vital organ functions.

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How Long Can You Go Without Food?

Many of us engage in diets or fasts to lose weight, which can be effective and healthy if done correctly. A balanced and nutritional approach is crucial for successful weight management. However, depriving oneself of food for extended periods—beyond a few hours or a day—can negatively affect both health and body mass.

Research indicates that the human body can survive without food for approximately 8 to 21 days. The following information will explain what happens to the body during this period.

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Post Day 1

When the body lacks food, it depletes its glucose or sugar stores within about a day. At this point, the hormone glucagon is activated, signaling the liver to produce more glucose. This emergency glucose is crucial for the brain’s survival and function and is primarily utilized for that purpose.

Post 2-3 Days

As time progresses, the body begins breaking down adipose tissue, or fat, to use as fuel. These fats are converted into ketones, acids in the liver which then enter the bloodstream. These ketones provide an alternative energy source for the brain, reducing its reliance on glucose. Ketones therefore play a crucial role in helping the body survive without food.

Post 7 Days

By day 7, the body’s fatty acid reserves are typically depleted. At this point, the body starts breaking down protein for energy, a process that depends on the initial amount of body fat and tissue present. Therefore, body composition is a crucial factor in how quickly the body will break down its own reserves. Around this time, the body begins to break down muscle tissue to obtain the necessary protein and sustain itself.

Post 14 Days

At this stage, muscle breakdown accelerates, leading to the loss of vital organ functions. As muscle tissue deteriorates, organs such as the heart, liver, and kidneys begin to fail, which can ultimately result in death.

What Are The Complications Suffered From Not Having Food? 

“Not eating enough food can result in several side effects such as fatigue, dizziness, hunger, low blood sugar, hair loss, skin problems, and impaired immunity. It can also lead to neurological problems over time.” – Melissa Mitri, MS RD

Why Does Water Intake Affect Survival Time Without Food?

It is possible to survive without food for a few weeks, but living without water is generally only sustainable for a few days. The primary reason is that the body has more reserves for food than for water. Water is essential for functions such as kidney function, which deteriorates rapidly without adequate hydration.

Studies indicate that a person needs at least 1.5 liters of water daily to survive without food, and adding salt to this water can enhance hydration. Water is crucial for maintaining blood circulation, electrolyte balance, temperature regulation, and metabolism. Beverages like lemonade with some salt in them can also prove to be very refreshing and even help with healthy weight loss if they are low in sugar.

When You Are Finally Able To Eat, Should You Be Careful About How You Consume Food?

“When you are starting to eat again after a long period of not eating, it should be done gradually. This is to reduce the risk of a potentially fatal condition called refeeding syndrome, which results in electrolyte imbalances and in some cases, cardiac arrest if food is reintroduced too quickly. To be safe, start low and slow, beginning with bland, low-fat foods that are easy to digest, and introduce one new food at a time. Meals should be very small, and gradually increased over time as tolerated over a few weeks.” – Melissa Mitri, MS RD

Final Thoughts

We hope this article clarifies how the body survives without food and the conditions affecting it. While safe diets and regulated fasting can offer benefits, starvation is not a recommended approach for weight management. It leads to severe alterations in body composition and can cause serious health issues, ultimately resulting in a terminally ill state. If you experience prolonged periods without food and face health issues as a result, please consult a medical professional immediately.For tips and guidance on how you can live a fitter and healthier lifestyle, check out the JustFit app!