Fasting has been around for virtually all of man’s time on earth. When we were hunters and gatherers, we had days of plenty and days of nothing. Our bodies are adapted to have periods of time without food. Once again, there are a plethora of articles on fasting, spanning hundreds of years, but Dr. Jason Fung does a nice job of putting it all together.
I feel it is important to be honest about your sources. Hippocrates (father of medicine – remember doctors all take the Hippocratic oath) believed there were great benefits to fasting. As a religious Jew, we have two 25-hour fasts during the year and several all-day fasts. (Our fasts are tough because we are not even allowed to have any water!) By contrast, the health fasts that I am discussing below definitely encourage plenty of water, tea, coffee, etc. Muslims have the month of Ramadan where they fast all day long for an entire month. Although these fasts are spiritually-based, it would not be surprising if they also had a health benefit. Other than my religious fasts, and my very frequent intermittent fasts of 14-17 hours, I have not yet done any longer fasts, but I am going to definitely try it.
What are the types of fasts?
There are intermittent fasts, which are at least 14 hours (though there is benefit to even 12 hours of fasting) and there are fasts longer than a day, which can even go on for weeks or months!
It goes without saying, do not plan a long fast without proper medical supervision and instruction.
What are the benefits to fasting?
Fasting is a great way to restore your insulin sensitivity, especially if you are not achieving what you want with the shorter intermittent fasts.
Many people will lose a significant amount of weight with fasting. To clarify a common misconception – you will NOT lose muscle mass, unless you stop exercising or your total body fat is very low – about 4%!
It is imperative that you maintain a healthy diet after the fast, if you want to keep the fat off (see my previous blogs on this topic). You will definitely put some weight back on when you return to eating, since some of the initial weight loss is due to water loss and will come back when you return to eating food.
There is a growing body of evidence that your body heals itself (autophagy) during a fast. There is a large increase in stem cells and other markers of anti-aging (increased telomere length etc). I believe over the next few years, we are going to see more and more evidence showing the biochemical benefits of fasting for anti-aging and longevity.
What is allowed during the fast?
You want to avoid all carbs and anything fake or artificial. You can and should have lots of clean, fresh water. You can have sparkling water. Avoid any artificial flavors or sweeteners! You can have coffee (black or with unsweetened almond or coconut milk or half and half), or tea. You can add natural spices to them if you like, such as cinnamon or cardamom. There is evidence that apple cider vinegar diluted in water is also very good for you. Natural bone or vegetable broth is fine, but must be natural. The latter is probably not necessary for a fast less than 24 hours.
I believe ketone supplements make fasting much easier since they cross the blood brain barrier and (If you want you can click here to find out which ketone supplement I use and to also learn how to buy it for yourself) will decrease your hunger. They also put you in a ketogenic state more quickly.
What happens if I get hungry?
You will get hungry! The more often you fast, the more used to it you will get, and the easier it will become. Fortunately, hunger is not a constant problem, but it will come in waves. Since you know that it will pass, it helps gives you the strength to suck it up. Fasting is much easier if you are very busy. I try and do my fasts on days when I am super busy in the office. It certainly makes my intermittent fasting easier when I am busy at work. It may make it easier to start a fast after lunch.
Is exercising allowed?
Yes! Most people who fast do great with exercising. The key is to drink lots of water and the other items listed above, such as taking in some extra salt. This encourages your liver to break down fat into ketones for energy. Your adrenalin and growth hormone levels increase during fasting and this may promote muscle creation.
How much fatigue should I expect?
There is often a period early on in the fast- often around 18 hours but varies from person to person – where they feel fatigue. However, this will pass and most people report increased, sustained energy during a fast – even for prolonged fasts lasting weeks and months! If your fatigue does not pass, you should stop fasting and get your blood checked.
Should I get dizzy or headaches during fasting?
No! You are probably dehydrated or low in sodium. Drink more fluids and add more salt to your fluids. (If you are on blood pressure meds, you may need to lower the dose). You do not have to rush and stop your fast immediately. Try these remedies and perhaps take a nap.
These are not dangerous and usually will resolve with taking magnesium, which is found as a pill at pharmacies and health food stores etc.
What should I do when I end my fast?
There is a strong tendency to overeat and that will make you feel lousy. Try and force yourself to eat light and slowly. This is psychologically driven and is not due to your body needing anything desperately.
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