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What Does Fasting Do to Your System?

by
author image Marie Dannie
Marie Dannie has been a professional journalist since 1991, specializing in nutrition and health topics. She has written for "Woman’s Own," the "Daily Mail," the "Daily Mirror" and the "Telegraph." She is a registered nutritionist and holds a Bachelor of Science degree with honors in food science from the University of Nottingham.
What Does Fasting Do to Your System?
A man reflecting in a peaceful setting. Photo Credit Design Pics/Design Pics/Getty Images

Fasting is a type of metabolic therapy that uses a mix of diets, enzymes and nutritional supplements to help the body remove toxins. In fasting, you voluntarily abstain from consuming some or all foods and liquids. During a fast, your body’s digestive system undergoes several changes because it needs to rely on stored energy to provide fuel for your body’s needs. The types of changes your body experiences is determined by the length and type of fast you undertake. Before doing a fast of any kind, consult with a doctor to ensure it is safe for you to do so.

Length Of Fasts

The length of your fast will determine how many stages of fasting you go through. Even a short fast, which, according to the American Cancer Society is between one to five days, will bring you through the first stage of fasting where your body uses up stored glycogen. This is the case for water, juice and dry fasts, the latter being a fast where no food or liquid is consumed for the entirety of the fast. The second stage, which focuses on using fats as an energy source, only occurs with fasts that are three days or longer for water fasts, and four days or more for juice fasts.

The First Couple of Days

During the early stages of any fast, your body makes use of the glycogen available from your last meal, to provide energy for your body. According to Ralph Cinque, doctor of chiropractic medicine writing for the International Natural Hygiene Society, the body progresses through the gastrointestinal phase within six hours on a dry or water fast. After this, it moves onto the glycogenolysis phase. On a juice fast, because you are still ingesting nutrients, your body takes longer to move to the glycogenolysis phase, where stored glycogen in your liver is used to fuel your body. Glycogenolysis can last for two days on a water fast, and upwards of three to four days on a juice fast.

On To Ketosis

According to the International Natural Hygiene Society, once your body’s glycogen stores have been used up, the body begins breaking down stored fats to provide energy for the brain in a process called ketosis, the second stage of fasting. Ketosis most generally starts on day three of a water fast, and between days four and seven on a juice fast. During ketosis, your body also begins using fewer proteins as an energy source, and only 20 grams of protein are used each day if your fast goes into a second week, down from 75 grams per day. While fat burning is ideal for those looking to lose weight on a fast, if you are obese or overweight, you need to be careful that you do not use up your body’s non-essential protein resources, which can lead to severe weakness after a long fast, including possible damage to heart muscle.

The Detoxification Process

Fasting can be a way of encouraging your body to detoxify, getting rid of toxins that have built up due to metabolic processes, as well as exposure to chemicals, pollutants and medications. While there is little scientific evidence supporting detoxification methods, including fasting, the American Cancer Society states that many practitioners claim it helps reduce acne, allergies and headaches, as well as helping lower blood pressure and reducing the risk of heart disease. Dr. Ben Kim, a Canadian chiropractor and acupuncturist, states that fasting can help improve energy levels and sleep quality, and reduce anxiety and tension.

Weight Loss and Digestive Health

In addition to detoxification, weight loss is one of the most common reasons to go on a fast. Because of the reduced calorie intake, many people experience rapid weight loss while on a fast, losing between 2 to 3 pounds during the first few days, and then roughly half a pound a day after the initial rush. The average weight lost is 1 pound per day of fasting. Fasting also gives the digestive system time to rest, potentially leading to reduced or cured digestive disorders, and a stronger digestive system. It can also help you achieve regularity in bowel movements as your system has had a rest and is cleansed of toxins.

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