We have to have food to survive, but as everyone learned in school, the body can last longer without food than water. In fact, some studies show that some people can go up to 70 days without food. This is because our bodies are designed to withstand stress. The defense mechanisms triggered when you don’t eat can help you to survive as long as you stay hydrated.
There is a lot of talk about diets based on ketosis and starvation mode diets. Starvation mode is what your body can go into if you don’t eat. While your body can adjust to a lack of nutrition it can only survive for a few weeks if you are also taking in enough fluids.
There are a lot of factors that can determine whether or not you can survive a fast of longer than 2 weeks, including genes, health, level of hydration and other factors. Regardless of how long you can go, here is what happens to everybody during 3 weeks of not eating.
Within 6 hours
Within 6 hours of not eating your body is using the glycogen it created by digesting food that enters the bloodstream as glucose. This is the primary fuel of the body. Once the 6 hours is up, the body will turn to consuming excess fat and transforming it into glucose for distribution to cells and tissues via the bloodstream too.
After 3 days
Once you have gone 3 days without food you enter into what is known as the “starvation mode.” This is a process that the body uses to survive lack of nutrition. Fat stores are gone and the brain needs glucose to function. It begins to use the stores in the liver through a process called ketosis. The ketone bodies replace glucose as fuel for the brain. The body metabolism lowers significantly so what stores of fuel are left is directed towards the brain.
3 Days to 3 Weeks
After 3 days the liver has no more stores of fuel for the body and brain to convert and consume. This is when the process of autophagy begins to occur. This refers to the process of the body breaking down its proteins in order to create fuel for all its systems. That protein comes from the destruction of muscle tissue, which is one of the tissues highest in protein in the body. This is not a consistent process but peaks after 72 hours before the metabolism slows again to act to conserve protein.
After 3 weeks
After 3 weeks the body continues to look for protein sources to convert into fuel. Once the muscles are gone the only source left are tissues, with the highest concentration occurring in the organs. Before this usually happens, the lack of essential vitamins and minerals usually cause complications as your immune system becomes compromise. If you do not become ill, you will fall into a vegetative state followed by death. People in the final stages of starvation can usually be identified from their lack of muscle mass, lack of energy and bloated stomach.
It is important that you understand what happens when you don’t eat and the seriousness of not eating as many people use not eating as a way to lose weight. If you choose to starve yourself, even temporarily, it can create irreversible effects on the body that can lead to death.
When no food is coming in, the body consumes what it already has inside. That begins with fat and then moves onto muscle and other tissue. It slows your metabolism down to conserve energy too, so you won’t lose much weight at all. When you start eating again, the body will keep the metabolism low and pack on weight because it is trying to build a reserve. Starvation can alter body composition and processes that can jeopardize organ function and overall health. The effects created by it are irreversible and it is never recommended as a way to lose weight.