Medically reviewed by, Russell Braun RPH
All the diets out there claim to be the answer. From low fat to low carb, vegetarian, vegan or Mediterranean, how can you know which is best? At the end of the day there is no one size fits all diet that is for everyone. Instead of being a diet that focuses on what you should eat, intermittent fasting is about when you should eat. The benefit being that intermittent fasting can induce autophagy.
1. What Is Intermittent Fasting?
As you might gather from the name fasting refers to a period of time where you don’t eat. The intermittent part comes in by breaking up meals so that there are periods when you do not eat. The core idea is that your body goes through times where you are fasting. Which can lead to some major benefits.
Therefore, intermittent fasting is not a diet itself. It is more of a process for when you will eat. For instance you could be veegan, vegitarian, keto, paleo or any other diet and still practice intermittent fasting (IF).
Why is fasting important?
If you think back to the time of our ancestors, there was not food readily avaialble. Thousands of years ago there were no groceries, convenience stores or certainly no fast food. In fact, people would go extended peirods of time without eating.
“Fasting is actually more natural to your body than eating three meals a day plus snacks.”
Fasting activates pathways in how your body metabolizes food that gives you energy. The major sources of this energy are fats, carbohydrates and protein. When fasting energy that was stored in the form of fat is broken down so it can be used for energy.
This breakdown of fat leads to ketones being formed. Ketones are the other form of energy your body can use besides the number one source, which is glucose.
In addition, fasting can increase levels of a molecule called NAD (nicotinamide adenine dinuclueotide) believed to slow down the effects of aging. NAD has been shown to activate sirtuins, also known as “gardians of the genome”. More research on NAD is needed, but most clinicians think it holds promise.
Processes That Occur During Fasting
The table below contrasts some of the processes that go on in your body when you eat vs fast.
|Non Fasting State||Fasting State|
|Insulin secreted||Glucagon secreted|
|Growth mode||Repair mode|
|mTOR activated||mTOR suppressed|
|NAD suppressed||NAD created|
|Fat creation||Fat breakdown|
|Increased inflammation||Decreased inflammation|
|Growth hormone suppressed||Growth hormone released|
Non fasting – Refers to times after eating and while digestion is occurring, which leads to insulin secretion. Insulin is a hormone the pancreas releases in reponse to food ingestion. It helps get energy from food to be taken up by your cells. This also induces pathways like mTOR (mammalian target of rapamycin) that lead to suppressed levels of autophagy and NAD. When energy is abundant your body stores it as fat. These processes and burning of glucose for energy lead to oxidative stress and increased inflammation.
Fasting – Times when you have not eaten and digestion of previous meals is over. This leads to glucagon secretion. Glucagon is a hormone released by the pancreas when blood sugar levels in the blood are low. It starts processes to breakdown fat so it can be used for energy. This also leads to pathways like mTOR to be suppressed and more NAD is created. With less oxidation of energy sources occuring, inflammation decreases.
2. What Is Autophagy?
The word autophagy means exactly what the two parts of the word mean in Greek.
Auto – Self
Phagy – eating or devouring
While it may sound strange, this is a normal process that naturally occurs in humans. This is of course regulated and removes damaged and dysfunctional parts of our cells. Think of it of a recycling of parts to keep too much clutter from accumulating.
Autophagy is controlled by a process known as the mTOR pathway. This pathway is believed to be the key regulator of how cells should use nutrients from the food we eat.
Eating = cell growth
Fasting = cell cleansing
Autophagy is important to ensure that cellular resouces are redistributed to where they are needed. Ultimately, this process is important for cell survival. Some mistake another process known as apoptosis, or programed cell death with autophagy. However, autophagy does not kill the entire cell, instead just recycles components of it.
3. Does Autophagy Happen With Intermittent Fasting?
There are two main ways that autophagy can be induced. Both make the body think that it is being deprived of nutrients.
In response to fasting and exercise the glucose in your blood stream will drop. This will result in your body starting to produce ketones from fat as a source of energy. This state of ketosis can induce pathways that lead to autophagy. Therefore intermittent fasting can also be expected to lead to autophagy.
When blood sugar levels drop this is seen as a positive stress on the body. Exercise has also been shown to initiate these processses in the peripheral tissues and the brain.
You might be wondering when does the body build itself up again if autophagy starts to occur during fasting or exercise. While autophagy is breaking down components of the cell back into building blocks, fasting actually causes growth hormone to be released. This growth hormone subsequently leads to producing new parts for the cells.
4. How Long Do You Have To Fast For Autophagy?
Intermittent fasting can be done in different ways, so how long does it take before autophagy begins? Autophagy requires blood sugar levels to drop before glucagon is released which allows the process to begin. Most sceintist agree this process takes at least 14 hours minimum.
Several different intervals can be used for intermittent fasting. Typically the length of the fast can be broken into timeframes. Some examples include (not an all inclusive list):
- 24 x 2
16/8 refers to condensing all your eating into 8 hours out of the day. Therefore, the other 16 hours are fasting. This can be easy to incorporate by skipping breakfast, then eating lunch and dinner in an 8 hour window.
24 x 2 is the idea where you will fast for 24 hours, but only two days out of the week. The other 5 days you would eat as you normally do. While easy to do once many people find it challenging to not eat for the entire day repeatedly.
5:2 simply means that you restrict your calorie intake to 500-600 calories per day 2 days per week. The other 5 days you eat as you normally would. This method is easier for some people than trying to go an entire day without eating.
5, Is Fasting For 14 Hours Enough?
Clinical research looking into how long it takes for autophagy to start is mixed. However, researchers think it takes at least 14-16 hours for autophagy to begin. The longer you fast the more areas of the body will begin autophagy.
Studies have shown that after 12 hours of fasting your body starts breaking down fat for energy. This process is known as ketosis and it helps to trigger autophagy. That being said, 14 hours is probably just enough to get things going. Based on that knowledge teh 5:2 method may not allow full autophagy to commence.
Can’t wait any longer to eat than 14 hours? Try exercising before you do have the next meal. This would be the best way to get the proces kicked into high gear in that timeframe.
6. What Can You Drink While Fasting For Autophagy?
Water can and should be consumed at any time while fasting without concern about breaking the fast. Water provides hydration that is missing from the foods that you normally would be eating. However, other beverages may contain enough calories to break your fast. Therefore, you need to know what to drink to keep autophagy going.
The following are generally recognized as acceptable drink options:
You want to use water to fill your stomach when hunger pains come on with fasting. Most people find that drinking some water will get those sensations to go away.
Drinking coffee without added sugar or cream can be a safe option. A small amount of milk is acceptable to and can help prevent hunger pains.
Green tea is full of polyphenols that can accelerate pathways that lead to autophagy. Other tea(s) are okay as well, but remember no sugar!
Apple cider vinegar
Diluting apple cider vinegar with water can help you stay hydrated. It also has other beneficial effects and may prevent food cravings.
A small amount of fats found in oils such as MCT oil or coconut oil can help tide you over. These will not prevent the ketones from being made during the fast which is a key part of inducing autophagy.
7. Does Black Coffee Break A Fast?
Black coffee without creams or sugars will not break a fast. There are very few calories in plain black coffee and the caffeine can help you make it through the fast.
Coffee has been shown to have health benefits like improved mental clarity and decreased inflammation. In fact, some think it may actually help promote the benefits of intermittent fasting.
Does Coffee Increase Autophagy?
Studies have looked at coffee and how it impacts autophagy. Granted these studies were done in mice, but it found that coffee increased autophagy. In fact, rapid autophagy was seen just a few hours after the coffee was consumed.
The other notable findings include:
- Both caffeinated and decaf coffee had these effects.
- Autophagy was found in several different organ systems.
Great news for coffee lovers who want to get the fullest benefits they can from intermittent fasting.
8. What Are The Benefits Of Intermittent Fasting And Autophagy?
Intermittent fasting has a large and growing body of evidence supporting its practice. Autophagy is one of the primary benefits of fasting. Many studies on autophagy have been done in mice and more human trials are certainly needed.
The table below summarizes the proposed beneficial effects of intermittent fasting and autophagy. Stay tuned, more research is ongoing that will provide more insights.
|Lower insulin levels||Improve insulin sensitivity|
|Break down misfolded proteins||Reduce risk of Parkinson’s and Alzheimer’s disease|
|Recycling old damaged cell components||Help prevent effects of aging|
|Reduce likelihood of defective cells||Reduce cancer risk|
9. What Are The Risks Of Intermittent Fasting?
Many people think that if something is good, more of it would be better. That is not always the case when it comes to your health. If you fast 5 days per week and eat normally only two days that will catch up with you.
In fact, excessive autophagy has been found to be detremental to health. Certain cells such as in the heart may be killed or weakened.
Checking with your doctor prior to starting intermittent fasting is a great idea. As with anything in life your circumstances may affect if intermittent fasting is appropriate for you. Certain diseases and conditions may not be good candidates for intermittent fasting. Some examples include:
- Heart disease
Don’t Forget The Meal After Your Fast Shouldn’t Be Junk!
You put int the sacrifice to make it through the hunger pains. Then you had your coffee and exercised to kick the autophagy into high gear. At this point your body is ready for some food to grow!
One of the worst things you can do is to eat a meal full of processed foods. These will be high in simple sugars and saturated fats. That can lead to blood sugar spikes causing you to release a ton of insulin and not get the full effects of your fast.
The best practice is to feed those hungry cells a meal of fruits, vegetables and healthy protein. A balanced nutritious meal with add to the benefits of your fast.
You did the hard part, now eat healthy to get the most bang for your buck!
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