What Are the Stages of Fasting?


Intermittent fasting is a very old concept that has recently grown in popularity. Breakfast comes from the term “break fast,” which is what occurs in our sleep. While we sleep, our body does not consume food. It is intended to focus on cellular repair, rest, and autophagy. Autophagy is the body’s ability to recycle old cells and make newer, improved ones. This process is activated when we fast. 

What Is Intermittent Fasting?

Intermittent fasting occurs when we refrain from consuming food for a period of time. We all do some form of intermittent fasting while we sleep. Some choose to increase this time by eating within certain time windows. For example, a person may choose to start their eating at noon and stop eating at eight pm. This would leave them with 16 hours of no eating and 8 hours of eating. People may choose to customize this plan with whatever works best for them. 

If you want to achieve real benefits from restricting your food intake, there are certain rules you have to abide by. General Intermittent Fasting Rules:

  1. No Eating During The Fasting Period.
  2. You Can Drink Water, Black Coffee, and Tea.
  3. Taking Supplements Is Allowed
  4. Fast for at least 12 hours.
  5. 16/8 is ideal (16 hour fasting period, 8 hour eating period)
  6. Fast for at least 2 days a week
  7. Eat a healthy, nutrient-dense diet. 

What Are The Stages Of Fasting?

There are four stages of fasting that the body encounters. Anabolic, Catabolic, Partial Ketosis, and Active Ketosis. When we think of fasting, we often think of starvation or deprivation. There is a great deal of research around using this process as a tool for cell renewal, weight loss, and immune support. Through these stages of restrictive eating, the body has the ability to heal itself. Stages of Fasting by Day: 

  • Anabolic Stage - This is the first four hours after eating. During this digestive state, your body uses all the carbohydrates, sugars, proteins, and fats from your last meal. Once these resources are distributed to fuel your body, the remaining nutrients are stored as glycogen or fat. 
  • Catabolic Stage - This occurs four to twelve hours after eating. The process of breakdown diminishes insulin and glucose levels. Glycogen fuels the body with energy. It helps regulate blood sugar in the body. 
  • Partial Ketosis - Partial ketosis takes place twelve to fourteen hours after ingesting food. Glycogen is depleted from the body. The body must utilize another form of fuel. This process of gluconeogenesis creates other avenues to attain glucose. Certain body parts need glucose to function, like the liver and kidneys. During this metabolic process, the body creates glucose from non-carbohydrate sources. It uses what is already in the body. 
  • Active Metabolic State - Gluconeogenesis differs from ketosis which is also happening at the time. In ketosis, the body burns stored fat and converts it to energy. Active ketosis occurs 18-36 hours after beginning a fast. During this time frame, the body detoxifies and uses autophagy to recycle damaged or old cells. Your body is not busy digesting food, so it can focus on other needed operations in the body. Many studies conducted on fasting show multiple health benefits. Evidence shows that fasting can help with age-related issues, skin health, cancers, dementia and Alzheimer’s, memory, and much more.
  • Replenishing Stage - The final stage of this process and debated as one of the most important phases. When reintroducing food after a prolonged fast, it’s important to choose easily digestible food. Your body has not had food for many hours, so your stomach acid and digestive enzymes are low. Introducing a high carbohydrate or sugary food will surely spike your insulin. Your body creates a balance of electrolytes in your system. By introducing carbohydrates too early after a prolonged fast one may cause cell damage. Depending on what you eat, you may experience stomach upset, cramping, or diarrhea. Being mindful of this, you may want to start with a nourishing soup or bone broth. This will help ease your stomach back into digestive mode. Stay away from sodium as well. If your stomach takes to the broth ok you may want to introduce some lean protein like chicken or fish. From there, you could try roasted or steamed non-starchy vegetables. 

What Is The Fat Burning Stage Of Fasting?

Your body begins to burn fat during the Partial Ketosis stage. At about 12 hours of fasting, your liver begins to break down fat and produce ketones. Fat burning increases from sixteen to 24 hours. Many people who fast regularly report seeing the best results after a sixteen-hour fast. 16 hour fast benefits include improvements in weight loss results, inflammation, and an improvement in overall health. Many people also experience increased mental clarity and focus. 

What Are The Different Ways Of Intermittent Fasting?

There are several popular windows or time frames to eat and fast. One can experiment with different schedules and find what works best for their needs. It’s always important to talk with your doctor before starting an intermittent fasting regimen. There are individuals who should not fast, especially for long periods of time. There are several different ways to set up your fast.

  • 8/16 - Eating for eight hours in a day and fasting for sixteen. This window is by far the most popular. Most people who incorporate this do this daily. You can tweak this window any way you like. Some may restrict for less time and have a 14/10 window where they eat for 10 hours in a day and fast for 14. 
  • 5:2 - This diet calls for people to restrict their calorie intake for two days and eat normally the remaining five. For women, the calorie intake is 500 and for men, it is 600.
  • 24 and 2 - This eating and restricting cycle involves refraining from food for 24 hours, two days a week. Many people on the day they are supposed to begin their fast eat one meal and then fast until the same time the following day. After they have met their 24 hours, they end their fast. It does not feel as long when you are eating one meal a day in that sense. 
  • Alternating - Some people fast every other day. They either choose to restrict their calories on these days or fast completely.
  • Long-term Fasting - Experienced fasters take on the challenge of long-term fasting cycles. This may include restricted calories or going totally without food. The effects are highly debated and should only commence under a doctor’s care. 

Does Intermittent Fasting Get Results?

There are many benefits to intermittent fasting. The results vary from person to person, but most people experience improved health from doing so. Some people should refrain from fasting. Those who are pregnant or breastfeeding, underweight, or children should not partake in this practice. Calorie restriction could become a detriment to their health and well-being. Most people who regularly fast develop a variety of positive results such as:

  1. Accelerated Weight Loss
  2. Higher Metabolism
  3. Improved Blood Sugar Levels
  4. Lower Levels of Inflammation 
  5. Less Brain Fog
  6. Lower Cholesterol
  7. Cancer Protection
  8. Combats Alzheimer's
  9. Slower Aging
  10. Better Sleep

Do You Burn More Fat When Fasting?

When your body is fasting, it converts stored fat into energy. So you are burning more fat when you fast. People who implement restricted-calorie fasts lose weight because they are restricting calories. Their body may not be in a high ketosis state, but the calorie restriction alone will help them to lose weight. 

Each person experiences different results. If one fasts and then gorges during the eating window, they may gain weight. If a person is fasting and then breaks their fast with unhealthy food, they may not experience all the health benefits fasting offers. 

What Happens To Your Body When You Fast For 16 Hours?

When you go without eating food for 16 hours, your body usually begins to convert its fat stores into energy. This releases ketones into the bloodstream, which allows your body to use them as fuel. This process is usually initiated by the liver when glycogen stores are depleted. Autophagy begins to occur throughout the body. 

This process may not feel very good at first. When beginning a fast, people often report feeling fatigued, brain fog, and a headache. 16/8 intermittent fasting results take time, and with consistency, people often have positive outcomes.  

How Long Do You Have to Fast to See Benefits?

Usually, people go into ketosis after the first week of restricted eating. For others, it occurs after about 3-4 days. It really depends on your eating and fasting patterns prior to intentionally fasting. After 12 hours, the body begins to burn fat, and it increases from there. There are many benefits of intermittent fasting. Figuring out which windows work for you will determine the level of benefits you reap.