Intermittent fasting (IF) is one of the oldest and forgotten habits of mankind and it’s making a comeback. Before I start giving examples, let me explain what intermittent fasting is. Intermittent fasting is going with no food for longer than usual period of time. One example can be skipping breakfast, another can be skipping dinner. It can also be an extended fast such as not eating for 24 hours, or for a few days. By today’s definition, it is also related to a concept called time-restricted eating (TRE). Some of the popular TREs are 16:8, 18:6, 20:4, 23:1 where the first number is the amount of time you spend in a day not eating. For example, in 18:6, you do not consume any calories for 18 hours and you restrict your meals in a 6-hour window, e.g. from 1 pm to 7 pm.
When you look at history and religious practices, you see examples of some type of fasting. In Judaism, the most well-known fast is the fast of Yom Kippur where one doesn’t eat or drink anything from sunset to darkness the following night. There are also other practices of fasting in Judaism if you want to learn more about them. In Islam, Muslims fast every day without food or water from dawn to sunset during the month of Ramadan. Monks use fasting as a tool that supports meditation and health.
In philosophy, especially in Stoicism, one can also see examples of fasting. Seneca the Younger, a Roman Stoic philosopher, statesman and dramatist, in his Moral Letters to Lucilius #18 touches on fasting. The title of the letter is “On Festivals and Fasting” and I highly recommend you read it. He writes “…let us become intimate with poverty, so that Fortune may not catch us off our guard.” He says that there is no reason why someone should fear or think that they are doing something great by fasting because this is simply what many thousands of poor people do every day. When you take a step back and see the meaning behind this letter and practice it, I believe it will make you stronger. Fast for 16 hours and ask yourself, if this was what you were fearful of.
It is really interesting that some practices, whether philosophical or religious, that are forgotten, often bring some sort of benefit to our lives. In the case of fasting, it is shown time and time again IF or TRE has major benefits. It can lower insulin which can help with insulin resistance. It can increase cellular repair. When you consume calories, body goes into building mode. But in the absence of calories for a long time, your body switches to the “cleaning mode.” This is called autophagy where your body cleans out the waste material in your cells. In order to protect the muscle tissue, the blood levels of growth hormone (GH) increases during a fast. So, unlike the common belief, you will not burn off only your muscle tissue. When you don’t eat for a long time, you also take away what cancerous cells feed off: glucose. When glucose availability is lowered, it may be beneficial in keeping the cancer cells in check (look up ketosis and cancer for more information). A prolonged fast can also help you express (turn on) genes that are related to longevity. IF and TRE can also be helpful with weight loss, simply because you tend to eat less calories during the day if you don’t eat all the time. If you are a person that is okay with not eating, but once you eat you cannot stop grazing through food and snacks, maybe you can give IF a try. Not eating also helps your body to get rid of free radicals that can damage your cells. This process lowers oxidative damage and inflammation in the body. In my opinion, once you are used to not eating, it can also increase focus and productivity. Because when you know you are skipping breakfast, you have one less thing to worry about and one less decision to make.
Should everyone do IF or TRE every day for the rest of their lives? No! This notion of taking things to extreme is never helpful, e.g. saying you will never eat a slice of bread even though you are not celiac. If your diet is not healthy, fix that first. If you are not sleeping enough, fix that first. If you are a high charging athlete, or a person that trains twice a day, or someone that works at a job requires you to work really hard, e.g. construction worker, by all means, you are already probably in a really good shape. You are also putting your body into enough stress already, so you most likely do not need another stressor. That brings me to my next point. If you have a really stressful job (you may consider finding a different job), do not fast. You kind of need to be in the right condition mentally, emotionally and physically. If you think you are going to have relatively easy day, try fasting. When you are sipping your morning cup of coffee and you realize you are not hungry, try fasting. When you are recovering from a really hard workout or going to do a really hard workout, eat. If you are truly hungry, eat. There is no need to prolong your fast just to suffer. For anyone that is willing to try fasting, there is an app called Zero that can help you keep track of how long you’ve been fasting. I believe it’s free and I believe it is put out by Kevin Rose. Even though I never met Kevin, I’ve been a guest on his wife’s (Dr. Darya Rose) podcast, Foodist. So, on behalf of everyone, thanks Kevin for the app.
This goes without saying but just in case, if you have any medical conditions, you should consult your doctor before you practice IF or TRE. Oh also, just like any other article, this article should not be taken as a medical advice and I am not a doctor. I’m just a guy that researches health topics who also rambles and posts stuff on the Web :)