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What is Intermittent Fasting?

Intermittent Fasting (IF) is the practice of abstaining from food and drinks for a specific period of time. Intermittent fasting basically boosts our metabolism, reduces inflammation, improves cognitive function, and improves overall health.

It forces cells to engage in activities that aren’t normally activated when a constant food supply is available. When in a state of fasting, the cells must rely on some other materials and processes to generate energy because the body is unable to obtain glucose as it normally does.

Consequently, the body starts the natural method of creating its own glucose, gluconeogenesis. The liver is the one that does the process of turning non-carbohydrate products such as fats, amino, and lactic acids into glucose energy. Since intermittent fasting causes our bodies to conserve resources, the basal metabolic rate improves, resulting in lower blood pressure and heart rate.

IF is a practiced way to lose weight. Historically, it is a part of various religious practices as well.

Q: So how long to see weight loss results with intermittent fasting?

A: While you can experience some weight loss in as little as a week, significant weight loss will take around 10 weeks, so stay in it for the long game. Remember it took your body months/years to add the extra weight so “rewiring” your metabolism takes up to 10 weeks on average.

Let’s dive in to gain more information on the benefits of each fasting stage so you can choose if intermittent fasting is right for you.

What Are the 5 Stages of Fasting?

It’s not like all fasts have the same advantages. There are several fasting stages, while the advantages of fasting vary depending on how long you fast. The five major stages of fasting are the following:

  • Stage 1 – Ketosis

  • Stage 2 – Autophagy

  • Stage 3 – Growth hormone

  • Stage 4 – Insulin reduction

  • Stage 5 – Immune cell rejuvenation

Stage 1: Ketosis

16–18 hours after starting a fast, the metabolic condition of ketosis occurs as the body starts to break down and burn fat. Ketone bodies form as a result of this condition. Once the body can’t access glucose, brain cells, heart cells, and skeletal muscle cells use ketone bodies as an alternative energy source. Ketone bodies, or simply ketones, are substances produced by the liver during gluconeogenesis, a process that creates glucose in times of fasting. It’s an alternative source of energy. The brain uses them as a major energy source during periods of fasting where glucose is not available.

Before I began IF I ate my dinner at 5pm and only drank water during the evening, no snacking after dinner! After a week of that to get my head in the game, I start intermittent fasting by fasting for 12 hours the first 5 days, then 14 hours for the next 5 days and then 16 hours for the rest of the 10 weeks. Baby steps at first so my stress levels wouldn’t get elevated and set me up for failure.

Since ketones reduce appetite, your appetite will start to decline throughout the fasting period. Also, this stage is a great choice if you’re looking to slim down. Your body goes into a fat-burning phase, and because you haven’t eaten anything in a long time, you rapidly start to burn off body fat.

Stage 2: Autophagy

I think of this stage as the Marie Condo process of the body. Keeping what your cells love and getting rid of what no longer serves them. #1 benefit: Reduced Inflammation.

The body enters the repair phase after a whole day of fasting. It starts repurposing old and damaged cells while also reducing inflammation. This is the ideal stage if you want anti-aging or anti-inflammatory effects. Your cells become more functional when your body is under moderate stress. One of the things they do is trigger autophagy. During autophagy, the cells examine all of their internal components, replacing everything old, damaged, or not working properly with shiny new models. The old components will either be recycled or discarded. When referring to how long to fast for autophagy, it is recommended only twice a month.

Stage 3: Growth hormone

Also referred to as Human Growth Hormone (HGH), the human growth hormone is a vital hormone produced by the pituitary glands. It is responsible for growth, cell repair, metabolism, and body composition. It works in coordination with estrogen. The effects of low HGH levels include decreased life quality, fat gain, and increased risk of contracting diseases. It is therefore important to keep optimal levels especially during athletic training, weight loss, and injury recovery.

Scientific research shows that your lifestyle and diet greatly impact your HGH levels.

The amount of belly fat you have and HGH production are directly linked. People with large amounts of belly fats are more likely to have weakened HGH production and a higher risk of contracting disease compared to those with low belly fat levels.

A study found that those with thrice the amount of the control group’s belly fat had less than half of their HGH levels. Another monitored HGH release for 24 hours and saw a huge decrease in people with more belly fat.

Studies show that intermittent fasting can help boost your HGH levels. One such study found that after a 3-day fast, your HGH levels increase by more than 300%. A week later, they go up by a whopping 1,250%.

Because continuous fasting is just short-term, intermittent fasting is a more preferable approach. When you are fasting intermittently, you stay away from food for short periods. Usually, you fast for 16 hours with an 8-hour feeding window daily.

There are two ways in which this type of fasting can optimize levels of HGH in your body. First, it helps you get rid of body fat which has a direct impact on HGH production. Second, it suppresses insulin levels as during eating, your pancreas secretes insulin. High insulin production is known to disrupt the production of growth hormone.

Stage 4: Insulin reduction

Even though fasting leads to lower insulin levels, it does not mean that it is 100% beneficial. For example, the insulin levels in the body reach their lowest point 54 hours after you start fasting. It is considered a positive thing because it can reduce inflammation, improve insulin sensitivity, and reduce insulin resistance. Remember you are in it for the long game. However, lowering blood sugar levels can cause some negative effects, such as excessive thirst and hunger. So, stay hydrated. Body weight divided by 2 = oz. per day of water needed for optimum cellular health.

Stage 5: Immune cell rejuvenation

The body breaks down old immune cells and regenerates new ones 72 hours after starting a fast. In many cell populations, prolonged fasting lowers circulating insulin-like growth factor 1 (IGF-1) levels and protein kinase A (PKA) activity.


Fasting over longer periods of time can cause some unpleasant side effects, so it is not recommended if the primary purpose is losing weight.

Some of the negative effects include headaches, constipation, crankiness, and lethargy. Fasting can cause the individual to overeat, which will end in low body energy and stomach problems.

What Is the Fat-Burning Stage of Fasting?

Fat burning is actually a fasting stage that starts after 14–16 hours of fasting and increases between 16–24 hours of fasting. In this stage, you’ll produce and use ketone bodies for energy since glycogen will be reduced. Fat cells in the body produce free fatty acids as a result of fat breakdown. PPAR-alpha (a liver fat metabolism regulator) is programmed, which ensures that those fatty acids are used during ketogenesis.

How Long Does It Take to Go into Fasting Mode?

Entering into fasting mode will take many hours after your last meal. The time varies from person to person, but 12 hours is a common estimate. I track my fasting time in a journal. I start my fast at 5pm and fast until 9am the following morning. Consuming only herbal tea and water outside the eating window of 9am-5pm. In the eating window I focus on consuming nutrient dense foods with clean protein, good fats & fiber with each meal.

The five stages of fasting can help people in reducing the number of calories they eat. Intermittent fasting is an effective way to boost your fitness. It’s cheap, easy to do, and relatively safe for the majority of people. Each stage is distinct in terms of the body’s primary source of energy and how it influences the metabolism and hormone levels. You decide the duration of your fast based on your health objectives.

Before considering an intermittent fasting program, please consult your healthcare provider to discuss whether it’s right for you.

Click Here to learn more about IF, ways to detox your body and balance your hormones.

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