Simulation Reveals How a 36-Hour Fast Impacts the Body
Fasting has long been part of human history, whether by necessity or choice. Many religions and cultures across the globe practice fasting as a meditative and cleansing ritual for the body. Some researchers speculate fasting could have been done due to food scarcity in older human history. Today, fasting effects, from intermittent to water, or even extended fasts like a 36-hour fast, are the subject of chatter in social media wellness communities.
As more people explore intermittent and extended fasting for health, weight loss, or mental clarity, understanding the effects of fasting on the body is vital. Recognising whether fasting is for you is crucial, as it can be dangerous for some populations. Seek medical advice before going on a fast, especially extended fasts like the 36-hour fast. However, when done safely, it is purported to provide various health benefits. We’ll explore the hour-by-hour effects of fasting, the science behind these changes, potential benefits, and important precautions. Keep reading and you will also be able to watch an interesting simulation depicting what happens in our bodies throughout a 36 hour fast.
The Hour-by-Hour Effects of Fasting
When you fast for 36 hours, your body goes through many important changes. Each hour triggers a new process that helps your body use energy differently and repair itself. Knowing these changes can help you decide if fasting is right for you and how to do it safely. Let’s explore what happens inside your body during this extended fast.
0–4 Hours: The Anabolic Phase
During the first 4 hours after eating, your body digests food and uses sugar from your meal for energy. Your insulin levels stay high to help move sugar into your cells. This phase is called the “anabolic phase” because your body focuses on building and repairing tissues using the nutrients from your food. Your energy mainly comes from carbohydrates during this time, keeping you active and alert.
4–8 Hours: Glycogen Use
After about four hours, your insulin levels typically drop. Your body responds by using stored sugar called glycogen for energy. Glycogen is stored in your liver and muscles and provides energy when you are not eating. This phase is called the “catabolic phase” because your body breaks down stored energy to fuel your body. This switch helps maintain your blood sugar and energy levels during fasting.
8–12 Hours: Fat Burning Begins
By the time you reach eight hours without food, your glycogen stores begin to run low. Your body then starts burning fat for energy instead of sugar. This change can make you feel hungry or tired at first as your body adjusts to the new fuel source. Burning fat means your body turns fat into energy, which is important for people trying to fast to lose weight.
12–16 Hours: Entering Ketosis
Around 12 hours into fasting, your body enters a state called ketosis. In ketosis, your liver converts fat into molecules called ketones, which your brain and muscles use for energy. Insulin levels fall even further, allowing fat burning to increase. Many people feel more focused and less hungry during this phase because ketones can reduce appetite and provide steady energy.
16–24 Hours: Autophagy and Repair
After 16 hours of fasting, your body activates a process called autophagy. This is a cellular process where your cells cleans out damaged proteins and recycle them to maintain energy and cellular health. Autophagy helps remove toxins and old proteins that could harm cells. Exercise during this time may boost autophagy even more. By 24 hours, your body also lowers inflammation and improves insulin sensitivity, which helps control blood sugar and supports overall health.