What IS Intermittent fasting

There are many definitions of fasting. The act of fasting is as old as humankind. Religious and spiritual practices have their own types of fasting. These fasting practices include abstaining from food, drink, and certain types of activity during periods or religious or spiritual events.

Medical and health practitioners use different definitions of fasting, too. In some cultures fasting for health  might mean abstaining from meat and certain types of grains. Other cultures define fasting for health as eating only rice or another food in their culture that’s considered easy to digest.

For our purposes, we are going to define intermittent fasting as intentionally not eating or drinking anything that contains calories for a set amount of time. This is the type of fasting used in most Western cultures for healing, weight loss, and cell rejuvenation. It’s also the type of fasting that has been most often studied and talked about for its health benefits.

Types of Intermittent Fasting

Skip one meal when the mood strikes you.

This is probably the least restrictive and easiest to implement type of fasting.  You simply skip a meal if you’re busy or not hungry. A lot of people begin their fasting experiment using this method. They might to commit to skipping three meals a week, as they feel like it as a way to test how fasting effects their body, mind, and mood.

Time restricted eating.

With this type of fasting, the individual chooses an amount of time each day during which they will consume all of their meals. Some common plans include:

One day a week: People who practice this form of IF choose one consecutive 24 hour period to fast completely. During those 24 hours they may consume water, tea, coffee, or other calorie free drinks. They person then eats whatever they typically would eat the rest of the time.

5:2  Choose 2 non-consecutive 24 hour periods and fast during those times. For example a person might choose to fast from 6 am on Wednesday until 6 am on Thursday, and then again from 9 pm on Sunday until 9 pm on Monday.

Alternate day fasting is eating a typical diet one day, and then fasting the next day. Some people who practice alternate day fasting eat one snack of roughly 500 calories during their fasting day. The exact number of calories eaten on a fasting day is calculated as percentage of your total daily calorie intake. The fasting day snack consists of only protein, fat and non-starch veggies.

Why use fasting for healing

Our bodies are designed to operate at maximum efficiency when food is scarce. It’s one of the ways pre-civilization humans survived. When you’re a nomad you might not find food everyday, so skipping meals was the norm. Our bodies breakdown old cellular material, heal, switch to fat-burning, and optimize energy consumption when we fast.

Scientists have studied the effects of fasting on organ and cell performance. Here’s what they’ve learned:

For the first 2 hours after you finish a meal your blood sugar rises.  Your body releases insulin and begins to digest your food.

After the first 2 hours your blood sugar begins to drop back down to your normal pre-meal levels.

5 hours after your last meal blood sugar levels will even out. Glycogen reserves might start to reduce. Your body is still digesting your last meal and will use stored glucose for energy.

About about 8 hours your liver has used most of its stored glucose. Some time around 8 to 10 hours after your last meal your body will start to make glucose from your body fat. This process is called gluconeogenesis.

After roughly 10 – 12 hours your body will begin to burn fat. You have little glycogen left, and fat cells are released into the bloodstream. Those fat cells travel to the liver. The liver converts the fat into energy.

Ketosis starts around 12 hours after your last meal. Glycogen is almost completely gone, and your liver starts converting that fat into ketones. Ketones burn cleaner and more efficiently than glucose. Burning ketones also produces an anti-inflammatory response in the body.

From about 18 hours to roughly 24 hours after your last meal your body will become more efficient at burning fat and creating ketones. At this point your body is getting about 60% of its energy from your body fat.  The additional ketones trigger more efficient metabolism.

If you’re doing a longer fast you’ll benefit from autophagy. This process starts about 24 hours after your last meal. Your immune system starts to clean any cells that are old or not working at top efficiency. Autophagy also leads to the breakdown of bacteria and viruses. Autophagy is the body’s cellular recycling system. The longer you fast over the 24 hour mark, the more efficient your body recycling system becomes.

From about 48 hours until about 56 hours your body will increase the level of growth hormone. HGH helps increase lean muscle mass and improves the health of your cardiovascular system. Many people who fast to this point report not feeling at all hungry.

From about 56 hours until roughly 72 hours after your last meal, your body becomes much more sensitive to insulin. This means it responds better to the insulin in your system than it did before. This is why people with Type 2 diabetes may notice their overall blood sugars become lower after a 72 hour fast. The effects of better insulin sensitivity during a long fast seem to continue after the person begins to eat normally again. The increase in insulin sensitivity also can reduce systemic inflammation and improve the autophagy process after the fast is over.

There is research that suggests fasting past 72 hours improves the efficiency of the immune system. As the autophagy process continues, the body must replace the recycled cells with new ones. As the fast continues, the pace of `cellular regeneration increases. This makes the immune system stronger and more robust.

People who should not fast

Fasting up to the 72 hour mark is generally considered safe for most people. In fact, if you pay attention you’ll notice that your body might use fasting as a healing tool. Have you ever had a cold, flu, or stomach bug that left you without an appetite for a couple days?  Losing your appetite is a widely experienced symptom of illness caused by a virus or bacteria. That’s because your body is working hard to activate all available healing modes.

However, there are some people for whom fasting isn’t safe.

If you have Type 1 Diabetes or are prone to experiencing symptoms of low blood sugar, you should not fast.

If you’re pregnant do not fast. Your body, and your baby’s body need a steady supply of nutrients.

Children and teenagers should only fast under the direction and supervision of their doctor.

If you are currently experiencing, or in recovery from any type of eating disorder you should not fast.

If you have any health concerns at all, you should consult your doctor before beginning any type of fasting program.

How to break a fast

Most experts suggest breaking a fast with broth, or soup that’s made with easy to digest low-starch vegetables, fat and easy to digest protein. Don’t use any spices, in this first meal.

Wait a couple hours before eating again to give your digestive system a chance to reactivate, or “wake up.”

Your second meal can be a little more substantial than soup, but don’t sit down to greasy, heavy food.

It’s recommended that you resume your regular eating plan gradually.

I tell my clients to resume eating slowly. Start with a small meal that’s light and easy to digest. Listen to your body, and give it the light food it’s asking for. When I complete a long fast, my body usually wants egg drop soup made with my homemade bone broth. But, each person’s body has different needs. Go slowly, and listen to those needs.


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