72 hour fast benefits

A 72-hour water fast, where only water is consumed for three days, can have several potential benefits. However, it’s important to note that fasting for this duration should be approached with caution and ideally under medical supervision. Here are some of the potential benefits:

  1. Autophagy:
  • Fasting can trigger autophagy, a cellular repair process where the body breaks down and recycles damaged cells and proteins. This can promote cellular health and longevity.
  1. Improved Insulin Sensitivity:
  • Fasting can improve insulin sensitivity, which helps regulate blood sugar levels and reduce the risk of type 2 diabetes.
  1. Weight Loss:
  • Fasting can lead to a caloric deficit, which may result in weight loss. It also promotes fat burning by depleting glycogen stores and utilizing fat for energy.
  1. Reduced Inflammation:
  • Fasting may reduce inflammation and oxidative stress in the body, which are linked to chronic diseases.
  1. Enhanced Mental Clarity:
  • Many people report improved focus and mental clarity during fasting due to stabilized blood sugar levels and the production of ketones, which can provide a steady energy source for the brain.
  1. Improved Heart Health:
  • Fasting can lead to reductions in blood pressure, cholesterol levels, and triglycerides, which are beneficial for heart health.
  1. Hormone Regulation:
  • Fasting can influence the secretion of hormones such as growth hormone, which plays a role in metabolism and muscle preservation.
  1. Digestive Health:
  • Giving the digestive system a break can help reset gut health and improve the balance of gut bacteria.

Caution and Considerations

  • Nutritional Deficiencies: Extended fasting can lead to nutritional deficiencies if not done correctly.
  • Electrolyte Imbalance: Prolonged fasting can cause imbalances in essential electrolytes like sodium, potassium, and magnesium.
  • Medical Conditions: Individuals with certain medical conditions, such as diabetes, heart conditions, or eating disorders, should avoid extended fasting without medical supervision.
  • Hydration: It’s crucial to stay well-hydrated during a fast.

When you undergo a fast, your body goes through several stages as it adapts to the lack of food intake. Here’s a detailed look at how the body reacts during different stages of fasting:

Stage 1: Post-Absorptive State (0-12 hours)

Time Frame: 0-12 hours after the last meal.

  • Glycogen Utilization: The body uses glucose from the last meal for energy. Glycogen stored in the liver and muscles begins to be broken down into glucose.
  • Insulin Levels: Insulin levels drop as blood glucose levels decrease, which reduces the uptake of glucose into cells.

Stage 2: Early Fasting State (12-24 hours)

Time Frame: 12-24 hours after the last meal.

  • Glycogen Depletion: Liver glycogen stores become depleted.
  • Gluconeogenesis: The body begins to produce glucose from non-carbohydrate sources like lactate, glycerol, and amino acids (proteins) through a process called gluconeogenesis.
  • Fat Utilization Begins: The breakdown of fat stores (lipolysis) increases, and fatty acids are released into the bloodstream to be used as an alternative energy source.

Stage 3: Fasting State (24-72 hours)

Time Frame: 24-72 hours after the last meal.

  • Ketogenesis: The liver converts fatty acids into ketone bodies, which can be used as an alternative energy source by the brain and other tissues. This state is known as ketosis.
  • Increased Fat Burning: The body relies more on fat stores for energy, reducing the reliance on glucose.
  • Protein Conservation: The body starts conserving protein and uses fats and ketones as primary energy sources to protect muscle tissue.
  • Metabolic Adaptations: Hormones like norepinephrine are released to maintain energy levels, and metabolic rate might slightly decrease to conserve energy.

Stage 4: Prolonged Fasting State (72+ hours)

Time Frame: More than 72 hours after the last meal.

  • Deep Ketosis: The body is in a deep state of ketosis, with high levels of ketones in the blood. This becomes the primary fuel source for the brain.
  • Autophagy: Autophagy, a cellular cleaning process, is enhanced. The body breaks down and recycles damaged cells and proteins.
  • Hormonal Changes: Levels of insulin are very low, and levels of growth hormone increase, aiding in fat metabolism and muscle preservation.
  • Protein Sparing: The body minimizes muscle protein breakdown to conserve muscle mass, relying more on fat and ketones.

General Benefits and Risks


  • Cellular Repair: Enhanced autophagy and reduced inflammation.
  • Metabolic Health: Improved insulin sensitivity and lipid profiles.
  • Mental Clarity: Some report increased mental clarity and focus due to stable blood sugar levels and ketone production.


  • Nutritional Deficiencies: Extended fasting without nutrient intake can lead to deficiencies.
  • Electrolyte Imbalance: Depletion of essential electrolytes such as sodium, potassium, and magnesium.
  • Medical Conditions: Potentially harmful for individuals with certain medical conditions like diabetes or heart disease


If you are looking for “fast exception items” in the context of fasting, these typically refer to items that do not break a fast or are allowed during a fast due to their negligible impact on the metabolic state. Here are some common exceptions:

  1. Water:
  • Essential for hydration and does not interfere with fasting benefits.
  1. Black Coffee:
  • Low in calories and can boost metabolism without breaking a fast. Avoid additives like sugar or milk.
  1. Herbal Tea:
  • Similar to black coffee, herbal teas without added sweeteners or calories are generally accepted.
  1. Electrolyte Supplements:
  • Important for maintaining electrolyte balance, especially during prolonged fasting. Look for sugar-free options.
  1. Apple Cider Vinegar:
  • Often used in small amounts diluted in water. It’s believed to support digestion and metabolism without breaking a fast.
  1. Bone Broth:
  • Although it contains some calories, bone broth is sometimes allowed during fasting periods, especially during longer fasts for its nutrient content and electrolytes.


  • Minimal Caloric Intake: The idea is to consume items with minimal or no caloric content to maintain the fasting state.
  • Individual Goals: The strictness of what is allowed can vary depending on individual goals (e.g., weight loss, autophagy, ketosis).
  • Medical Advice: Always advisable to consult with a healthcare professional before starting any fasting regimen, especially if including exception items.


For further reading on fasting protocols and what might be considered acceptable exceptions, you can refer to:


The body’s response to fasting involves a complex interplay of metabolic processes that shift energy utilization from carbohydrates to fats, ultimately leading to the production of ketones. While fasting can have potential benefits, it should be approached with caution and ideally under medical supervision, especially for prolonged periods.

While there are potential benefits, a 72-hour water fast is not suitable for everyone and should be undertaken with caution. Consulting with a healthcare professional before starting such a fast is advisable to ensure it is safe based on your individual health circumstances.