Each day, our body receives energy from the food we eat. Fasting for a long time means no energy enters the body, which can affect the digestive system. At the beginning of nutrient energy deficiency, the body compensates by using energy from other sources instead. Normally, our body uses glucose as fuel to provide energy for muscle movement, brain function, heart pumping, and so on.
Using alternative energy when “fasting”
Normally, when we eat, the excess energy that the body does not use is stored for use during nutrient deficiency. This is called “glycogen”, which is stored in the liver and muscles as an energy source. When blood sugar levels drop or the body lacks nutrients, the liver converts glycogen into “glucose”.
After the body uses up the stored glycogen, it will start breaking down fat or using fat stored in the body, called “ketones”, which are similar to sugar molecules. If nutrient deficiency continues and the body has used up all other sources, it will begin to break down muscle protein as a substitute.
Fasting affects mental health
Fasting for too long is not just about nutrient deficiency but also affects our mental state. Hormonal changes in the body can cause depression, hunger, or a decreased desire to eat.
How long can a person survive without eating?
A person can survive without nutrients for about 6-8 weeks. However, it depends on whether the person is also dehydrated. Generally, without water, survival is only 1-2 weeks because dehydration causes inability to urinate, accumulation of waste in the body, which can lead to kidney failure, low blood pressure, or even shock and death.
Guidelines after fasting for several days
When resuming eating, choose foods that are easy to absorb, such as gel foods that help adjust the intestines, allowing immediate absorption. Continue this for about 4-7 days to help the body adapt by creating new cells and regaining the ability to digest and absorb food. Food types and daily amounts should be limited appropriately, gradually increasing intake step by step. Avoid foods that are too strongly flavored. Also, observe whether there is diarrhea; if diarrhea persists, it means the body is not yet ready to digest and absorb.
Additionally, eating after prolonged fasting requires caution regarding “Refeeding Syndrome”. Since the body has not received nutrients, when food is suddenly reintroduced, all cells start repairing simultaneously and use energy all at once, causing the body to be unable to adjust. This can lead to numbness, cramps, seizures, or spasms. At the same time, new cell formation requires vitamin B1 to prevent problems.
