On Intermittent Fasting

This is a short write up of what I learnt about Intermittent Fasting (IF).

This article is outdated. You probably should update your knowledge of this with this one on health.

1. What is IF? Can you give it to me quick?

If you can think of IF as CF (Intermittent Fasting (IF) as “Continuous Fasting”), that’s that. What it does is flips the generally given advise and the modern way of life on its head and says, “When you eat and how much interval you give between the food intake is as important if not more important than what you eat”.

2. How do you do it?

One popular way is called 16-8. You fast for 16 hours in a day (or a 24 hour period) and restrict all your eating to a contiguous 8 hour period.

*contiguous / continuous 8 hour is the key part here. Otherwise, very likely eveyrone is doing a 21-3 fasting every day - if you count only the minutes that you are actively eating.

3. Define fasting please?

Super simple: Fasting means you are consuming “ZERO calories”. It doesn’t involve looking at an item, the constituents of carbs, fats, proteins or whether it has milk or wheat or meat or fruit or vegetables or not. It is as simple as it can get.

4. Why does it work?

Well, for one, you are not eating! Or you are eating less. (No shit Sherlock!). But let’s say you manage to still consume the same 2000 calories within the 8 hour period, IF still works because of the prolonged period you give the body to be in the “burning mode” as opposed to the “fat storing mode”.

5. Okay this is interesting enough that I want to learn more and rather from qualified people, can you give me pointers?

I am glad you asked. In fact, I would hope anyone who reads this drops this at this point and reads through the following wonderful life-changing illuminating books.

If you want to read only one book: The Obesity Code by Dr. Jason Fung

But you should definitely consider also reading: Why We Get Fat by Gary Taubes

While you are at it, in fact, even more importantly than the above, first watch this: Sugar the Bitter Truth by Dr. Robert Lustig: https://www.youtube.com/watch?v=dBnniua6-oM

Dr. Jason Fung has couple of other books (Diabetes Code and Guide to Fasting). Gary Taubes has written a bigger volume (Good Calories, Bad Calories).

There are lots of videos of Dr. Jason Fung on youtube that you might find illumniating.

And at this point, an important and much needed disclaimer that I am not a doctor or otherwise medically qualified. So use this write up only as an experience of “some one who tried it” and then learn more from these links and books and other research that you ought to do. Above all, use your common sense. Talk to your doctor, family, friends. I got curious likewise by a very good friend of mine who did this and advised me to read about. That’s what I did - read about a dozen books on the topic, many many dozens of googling, wikipedia pages and youtube videos later, I experimented and figured out a system that works for me.

6. What does zero calories food constitute of?

Well think of it more as liquids rather than solids (food). I don’t know of (rather haven’t tried) any solid zero calorie food. Only think I can even think of is ice cubes.

So on to liquids: Water (hot or cold), Black Coffee, Black Tea. Yup, that’s it! See how simple it is? No need to read labels or ingredients or measure the weight or dissect the constituents.

In short, Water: havea at it as much as it is safe for you to.

If you really want to hack the coffee/tea part, you can add splenda - which is zero calories and you will get some “sweetness”. Another zero calorie liquid is “Diet Coke” or any such diet drinks. There are also zero calorie chewing gums. But then again, in all these cases, beware of their side-effects.

7. What am I allowed to eat during the 8 hours of eating period?

Pretty much anything. But again, it would be best if you just stick what you would otherwise have done during an “8 hour” period pre-IF.

For the most part, folks try to optimize two meals in this period. Ideally not much snacking. Ideally not much carbs. Ideally not much calories. :)

8. Can you illustrate an 16-8 with some timings?

Say, your 8 hour eating period is 7am to 3pm, you can start with your usual morning beverage with a breakfast, a lunch and wrap up with a snack.

If you do something like 12 noon to 8pm, then your first meal is lunch and you get your afternoon snack/beverage and wrap up an early dinner.

The key is the other 16 hours - ZERO CALORIES. ZERO MEANS ZERO.

9. Is 16-8 the only way to do IF?

Not at all. You can tweak and try any settings as you please. Normally, given the current style of living, we have all tended towards starting the day with some calories (beverages) at 6-7 in the morning and go on till 9-10 in the night. So we have been doing 16-8 but in the wrong way - 16 hours of eating and 8 hours of continuous fasting (only in the night).

The idea of IF is to increase that 8 hour continuous fasting time to something higher, hopefully significantly higher.

If your current living style is indeed 16 hours of eating / 8 hours of continuous fasting (this would be 8-16), and you want to take it really slow and easy, by all means start with 9-15 (9 hours of continuous fasting). Try to keep increasing this to 10-14 (10 hours of continuous fasting) and then to 11-13 (11 hours of continuous fsating).. so on.

Ideally you want fast good results, right? So yeah, challenge yourself. Start with at least 12-12. (12 hours of continuous fasting) Or even a bit more at 14-10. (14 hours of continuous fasting).

12-12 should be very much doable - all you need is to fix one end of the day (either start eating a little later in the morning or stop consuming a little earlier in the evening before sleep).

14-10 is easy too : In fact, it is 12-12 with a 2-hour thrown in for good measure. Sorry, I just did the “just one more lap” or “just around corner” trick.

10. Is IF restricted to 24 hour windows?

Glad you asked. Not at all. There are as many types of IF as the human mind can conjure up.

One popular style is 36-12 (yes, that’s 36 hours of straight-fasting).

There is one called 5-2 - in this case, 5 days of normal eating and then 2 full days of fast.

A tweak to that is 2 days of extremely limited calories (like less than 500 calories per day).

There is also 25-5 - 25 days of the month in a normal lifestyle with 5 days of fasting (or extreme low-calories mode).

There are also improvisations of 5-2 with the 5 days itself being a 16-8 and 2 days being full fast (or low cal).

It could also be the other way, 5-2 to mean, 5 days of IF and then 2 days of no holds! This is especially a good technique in the starting phases if you want to try something during weekdays but want to party during weekend.

11. Wow, so which one is most effective?

Each one has their own merits. It is a long topic. I now introduce you to more topics : Autophagy, Dr. Victor Longo and … just start there and Google / Wikipedia / Youtube recommendation algorithms will take you the rest of the day.

12. Isn’t breakfast the most important meal of the day? And isn’t many small meals like 6-8 spread out throughout the day the way to go?

Nope. And Nope.

13. Isn’t low fat diet a proven technique?

Nope. In fact, it is the opposite. Many literature studies, experiments goes on to prove that FAT is not bad as it thought out to be.

Taubes and Fung would go even far and say, it is GOOD. In fact, it also seems that many athero sclerosis, what we call “bad cholesterol” (LDL), plaque in arteries are all created from Carbs as well.

While we are on that, a quick reminder that being overweight or obese is a precursor to a family of diseases they are now calling as “Metabolic Syndrome”. If left unchecked, this leads to Diabetes, Stroke, Heart Attack and Cancer and many others that in turn, stem from the previous list.

14. 16. What about calorie counting?


It works in the short term but not in the long term. In fact, Taubes and Fung go to great lengths (I mean about 50% of their books) to disprove the existing diet fads. I would write some notes here but honestly they have done such a terrific job with citations to scientific journals, studies and medical reasoning that it is really very important to understand the approaches that do not work.

Please read those two books (Obesity Code and Why We Get Fat).

15. What about Low carbs? What about some type of cuisine, food packages, shakes, juices…etc?

Maybe. IF + Low Carbs is a fantastic combination.

Taubes is all about Low Carbs.

Fung is all about IF but with a nod to low carbs when done with IF.

As far as custom cuisines, packages, shakes, juices are concerned, well, most of them seem to be a trick towards getting to low calories, low carbs, more healthy eating … or a combination of a few things.

Nothing stopping you from taking a cuisine package when doing IF as one of your meals.

Likewise, have a shake or two or three during your eating period. Heck, vegetable juices, salads are awesome.

16. What about Physical Exercise?

They are awesome! And in fact, necessary for a healthy life. Just that per Taubes/Fung, it is not the way to weight loss. You can read in detail in the books. Definitely check up on “BMR” (Basal Metabolic Rate). The theory in short is that your body is extremely good at figuring out efficiency. So in cases of eating less (calorie counting) and with physical exercises, one tends to take more rest or eat more to compensate for the loss created in another way.

17. Okay more seriously, why does IF work?

Non-snarky answer (as opposed to answer to question 4). Here is quick summary / understanding of scientifically what happens.

One of the most important hormones in the body is Insulin. It regulates the amount of sugar (aka carbs converted to the simplest form of sugar called glucose) in the blood stream. Insulin also does another important function : it signals the body to take the sugar out of the blood and store it in the cells in the form of fat for burning it later in “times of need”.

I put those quotes more mockingly since it was a great innovation by the biological systems to protect us in times of starvation, famine and what ever other things that nature and evolution threw our way. But nowadays we have arisen to the top of the food chain and for the most part are never in shortage of food. (With due apologies to the small percentage of folks who do endure food struggles).

Back to our superhero Insulin. As long as there is sugar in the blood stream (above whatever level your body has been conditioned to), the body will try its best to secrete insulin which will signal the cells to take that off and store it as Fat.

When your blood sugar starts falling off, hours after eating and doing other work, the body realizes that it needs energy. So it taps the cells to give out the stored fat - they go out. In fact, even though this is simply stated, this is an astounding, mind-blowing process. There are 100s of millions of cells orchestrating billions of chemical reactions to keep this symphony called “your life” to go on as smoothly as possible.

So now what happens when you have access to more food? And you also eat that food for prolonged periods of time? There is more sugar in your blood. Hence more insulin. Hence the body is the “store fat” mode for more time than “burn fat” mode. It takes only a tiny bit of inequillibrium to kick start things. An extra snack after an hour after a usual time, here or there, all adds up.

Contrastingly what happens when you are not eating for the majority of the time? The body is “burn fat” mode and hence you lose weight.

But it is not as simple either. Your body first uses by energy from Glycogen (glucose stored in an easier manner to be used up than fat). This is stored in the Liver. And your typical liver is estimated to have enough Glycogen power for up to 18-24 hours. So as you can see, with modern day lifestyles with 8-16 (8 fasting, 16 eating), we never get to even a place to empty the liver’s glycogen supply. Now you know why fat seems like a one way street and the fat accumulated wherever seems to never go away (even after you did that hard 2 hour hike or 30 min treadmill).

This also should now explain why prolonged fasting routines work even better. So when you fast 24 hours or more, the liver is empty! The body is forced to hit the fat stores. Jackpot.

There are many other benefits to this. Your digestion system gets a good well deserved break. There are other nice things too … as explained in the wonderful books/videos already cited.

Let me just tempt you a bit more: what happens when you fast beyond 48 or 72 hours? This is when the body goes in to a real panic mode. (Sorry, not having coffee in the last 3 hours does not constitute panic). It tries to conserve as much energy as possible and at some point realizes, crap, I am not getting calories, let me salvage stuff out of my own self. So in addition to toxins getting cleared, old cells die, they get cleaned out. Not just that, one of the first systems to go out is the immune system cells. (heck yeah, so don’t try this stunt without reading and learning more, and not without consulting a doctor, and especially not during covid times when you need all the immunity you can muster). But the autophagy theory (well not just a theory anymore, it won the inventor a small prize they award in Sweden). So anyways, the old immune cells die. You eat and your body now generates new immune cells. From what I understand it is kinda like the bone fracture or in a smaller way, the muscle breaking (with strength training). Your body now prepares a stronger version. And hence with stronger newer cells, you are a newer stronger, dare I say, younger you.

Cool? Intrigued? Yeah? Go check it out.

18. Is it safe to do?

If you have any preexisting condition, then definitely stop reading on the internet and go talk to your doctor (especially the ones who are very aware of and open to IF and such).

The general estimates go something like this. Without air, a human can survive just minutes. Without water, less than 7 days. Even after 24-48 hours, many body functions / organs starts shutting down. So yeah, just a friendly reminder, keep yourself well hydrated. And there is pretty much no diet regime that ever tells anyone to not take plain water! Also, here is another interesting theory. A lot of times what we think of as hunger is merely thirst or just a necessity to walk around put something in the mouth. (out of habit). Nothing like hot water, black coffee or black tea to quench your thirst.

And now coming to solid food, apparently the human body can go up to 30 days without food! No, I didn’t verify that.

I can only tell some personal experience. I usually end up fasting 18+ hours but set my goal as 16-8. (At least for me psychologically, being able to meet the goal every day and keeping the streak alive keeps me motivated). I have done 24, 36, 48 hour fasts too (but more as one shot experiments). The maximum I have done is 72 hour fasts (I have done it thrice).

Another question that comes up is : yeah, I won’t die, but won’t I faint?

Or even if I don’t faint, will I be able to do my work? function efficiently?

The answer to all that is surprisingly a resounding yes. More surprises awaits - please read the books.

Yes, it is going to be hard to start or first few days given that we have had our whole life to practice the opposite. But the body will get used to it.

19. But I do need my morning coffee / tea with milk / sugar and … ?

Yeah, I used to be that way too. You never know your limits until you push them. It took a couple of months but nowadays I am fine with Black Coffee.

There was a funny fb post a while back that goes: “COFFEE spelled backwards is EEFFOC and I don’t give EEFFOC until I have had my morning coffee”.

Reiterating from previous answer: Yes, it is going to be hard to start or first few days given that we have had our whole life to practice the opposite. But the body will get used to it.

20. Is there an app for IF?

There is one called “Zero” which is free and so far simple. It just has two buttons - “start fast” and “stop fast” and you can press only one at a time. :) You can choose from various IF routines. As I said before, I set it to 16-8 but I end up (and try to) doing 18+.

It used to be much simpler but then I guess their Product Managers couldn’t keep their hands to themselves. So they go about adding one or two features a month - almost all of which is useless to me. I am honestly afraid they are going to break it or take it away at some point. But then again, they are doing it for folks who pay money or want to pay. I am neither.

But then again, your clock (and body clock, believe me), will keep you strongly reminded of when you can eat next. All you need is then a Calendar to do the Seinfeld technique (of ticking every day you successfully did it and keeping the streak alive).

21. Any other references on IF?

Yes, please read the poem IF by Rudyard Kipling. IF you can follow that, you will live a happy life.

22. Anything else on fasting?

Yes, please read Siddhartha by Herman Hesse where the eponymous hero keeps saying, “I can think, I can wait, I can fast”. If you can follow that, you will live a happy life.

23. Okay, a bit more seriously please?

Honestly, I wasn’t being snarky. The poem IF and the book Siddhartha are far more valuable than anything else.

But in the spirit of IF, asking / reading / questioning conventional practices is a good first step. The whole science of Nutrition is hardly 100 years old. And it was only then that we even realized the macro-nutrients as Carbohydrates, Fats and Proteins. We have a lot more to discover and learn how the body works. There is a whole world of gut biome, gut-brain. There is another world of micro-nutrients. There is a whole another level of Mind-Body interactions / medicine. Yet another world of breathing, sleeping, physical exercises and mental health and how they all influenece each others effects.

In short, if we can take all the advantages and knowledge of modern science and medicine, and also the wisdom from our grandmothers or great-grandmothers, and use them as strong guiding principles, we can live a happier life.

Happy Reading, Happy Fasting! OM Peace, Peace, Peace!