Intermittent Fasting: A Basic Guide

I welcome any comments, questions, feedback and opinions about this article!

This article may be of interest to those who are seeking a method of structuring their eating routine in order to lose weight. I may periodically add extra information to this page as I find more. I do realise that this is a long read, but the information contained within is accurate to the best of my knowledge, complete with references (albeit written very untidily).

Before I discuss the concept of intermittent fasting, let me first outline a few definitions and terms I will use throughout this article:

Intermittent Fasting (IF): The practice of conducting shorter, but more frequent fasts. It involves frequent cycling between the fed and fasted states.

Fed state: The state your metabolism is in after eating a meal. Think of this as the time nutrition is being added to your body – your blood sugar level rises.

Fasted state: The state of your metabolism some time after the last time you ate. This can be thought of as the time when your body has fully absorbed the last meal and your blood sugar returns to baseline levels.

IF can be thought of as ‘regular’ fasting, with the exception that it is conducted intermittently or at regular intervals as the name suggests. What this means is that instead of fasting for a whole day for 1-to-several days a week, you fast on a more regular basis for shorter periods of time.

IF is not a diet – rather it is better thought of as a basis for structuring out one’s meals throughout the day. That being said, a healthier diet incorporating more fruit and vegetables will be more likely to produce better results using the structure provided by an IF routine.

IF works on the principle that your body goes into a fasted state after ‘x’ number of hours since your last meal, similarly to how ‘regular’ fasting would work. The time it takes for your body to transition from the fed state to the fasted state depends on how much and what it is you ate at your last meal. I cannot say, nor do I know how to calculate, exactly how long the transition to fasted state takes, however some brief searching implies that 8-12 hours is a reasonable guesstimate for the time achieve such a state. For those who eat smaller and healthier meals, this time may be reduced.

The reason why anyone would want to be in a fasted state would be that it provides a great opportunity to lose weight. Previously, you would directly use up some of the energy leftover from your last meal to carry out regular bodily functions. However in a fasted state your body cannot use such energy as it is no longer there, and thus turns to the next fuel source it can find: stored energy in the form of fat. Taking this further, if there is no longer any fat left for fuel, the next energy source your body turns to for its energy needs is muscle. Irrespective of whether you want a physically lean, muscular body or not, your heart is a muscle – meaning that if you continue to be involved in long fasts, you could end up having life threatening issues with your heart, and also likely have issues with the rest of your organs too.

This is where IF is a good solution: it effectively provides a better balance between being fed and being fasted. The goal is to be in the fasted state long enough to dig into your fat reserves, but also short enough to prevent muscle loss (eventually you would lose weight both in the form of fat and muscle mass). This allows people to lose weight whilst retaining as much of their muscle mass as possible, and as such IF is an attractive approach to bodybuilders who are aiming to get lean.

To further enhance the effectiveness of an IF routine, one should do some form of exercise during their fasted state. The necessary energy required to perform any form of exercise regime will have to come from your stored fat reserves, instead of simply burning off what you’ve just eaten in the case of exercising in a fed state.

Below I’ve given an example to illustrate how to create an IF routine, using the information discussed already to further explain in detail where necessary:

7:30am: wake up (in a fasted state), skip breakfast, drink a glass of water and/or have some black coffee. [zero/minimal calorie intake to prevent the fast from being ‘broken’. Breaking the fast would be detrimental at this stage].

8:00am: In your fasted state, go for a jog/lift some weights/do body-weight exercises/go to the gym. [Burn off some stored fat in the form of energy. This should enhance the rate of weight loss. But as always with weight loss, be patient – this takes time and effort].

8:30am: Head to work/school/wherever it is you may need to go on a day-to-day basis. [Not important to the IF routine, but I’ve illustrated here how I’ve been able to fit in some exercise in my fasted state before daily responsibilities take over].

11:30am/Lunchtime: Break for lunch and thus ‘break’ your fast. Have something healthy and nutritious, but remember to track your calorie intake at least. [We are now entering a fed state. This is okay because, as you’ll see later in this example, our last meal the day before would be at approximately 6:00pm. Therefore, if we assume it takes a maximum of 12 hours to enter a fasted state, we have now been fasting for 5.5 hours].

4:30pm: Head home from work/school/wherever you may be. [Again, not important to the IF routine, but illustrates that I can break my fast away from home].

5:30pm – 6:00pm: Have dinner, and remember to track your calorie intake. This will be the last meal of the day. [From now on, we count the hours and make a reasonable guess as to when a fasted state is achieved. If we ate dinner at 6:00pm, plan tomorrow’s lunch for 11:30am, then it will be a total of 17.5 hours since the last meal. Again, assuming 12 hours is required to enter a fasted state, we would have been fasting for 5.5 hours before tomorrow’s lunch].

9:30pm: Get ready for bed, ensure you get plenty of good sleep. [Sleep and appetite typically go hand in hand. Good sleep tends to keep appetite away amongst better willpower and stress management; bad sleep inhibits your ability to make good judgement and as a result comfort eating/overeating become more probable thus you are more likely to be unable to fast].

7:30am (next day): you wake up again in a fasted state, ready to do some morning exercise etc… [Repeat the plan and adjust accordingly for what you need to do today. By this point, you would be 1.5 hours into a fasted state].

To try and preemptively answer any questions at this stage, I will elaborate and discuss some more aspects of an IF routine.

“I cannot skip breakfast, the plan doesn’t work!” – Typically, an IF routine will cut out one meal from the day. I chose breakfast as that is easiest for me to work into my daily life. However, you could just as reasonably skip dinner, or condense breakfast/lunch/dinner into smaller meals which are eaten at closer times to each other (e.g. 10am, 1pm, 4pm respectively). This could mean that you enter your fasted state at a different time, possibly as late as 11pm if you have a very early lunch and skip dinner. The point is that IF can be adapted to suit you on a day-to-day basis, and does not even necessarily have to be adhered to every day of the week.

“I had black coffee with a dash of milk with my breakfast, have I broken my fast!?” – From what I can find, this is somewhat a grey area. The best answers I could find were along the lines of possibly, but not likely if a slightly milky coffee was all you had. My searches seemed to conclude that your fasted state is not an immediate ON/OFF switch – meaning that you are very likely fine having consumed a small amount of calories and your fast is not broken. It would obviously break if you had pancakes and syrup with your coffee however. As for putting a number on the required calories to break a fast, I could not guess. My searches suggest that a maximum of 50 calories is little enough to not break the fast.

“I can’t have lunch that late/dinner that early, what now!?” – This is not necessarily a problem. If you are able to split up the 24 hours of a day into the number of hours of ‘no eating’ and ‘eating’, you could realistically not eat for 14 hours and allow yourself to eat over the course of 10 hours. If dinner was the issue in the above example, and you decide to allocate 14 hours to ‘no eating’ instead of the 17.5 hours I planned, then you could realistically have dinner as late as 9:30pm assuming you have lunch at the same time in the example. I would think that as long as you can set aside 14 or more hours to not eating, then you could still benefit from IF – you would still allow yourself to be in a fasted state for approximately 2 hours a day (assuming 12 hours to enter a fasted state). To reiterate the key point here, IF is a flexible planning strategy which can work around your needs.

To summarise the key points of intermittent fasting:

  • Intermittent Fasting is the practice of conducting shorter, but more frequent fasts.
  • It is a meal planning strategy which can aid in fat loss.
  • It is NOT a diet – it does not necessarily change what you eat on a daily basis, just when you eat.
  • It is a flexible strategy which can adapt to one’s day-to-day life as necessary.
  • Exercising whilst in the fasted state can enhance the rate of weight loss.

My own thoughts and experience with integrating an intermittent fasting routine into my own day-to-day life have been good. I find it easier to stick to on the basis that you are not doing a whole day fast for example. Its day-to-day routine aspect also helps me to stick to the strategy more effectively as I get used to eating my meals at the same times each day. The strategy permits me to manage my calorie intake better as I find that I typically consume fewer calories this way – I find it easier to meet my calorie goals eating 2 larger meals than eating 3 smaller meals each day, as contradictory as that sounds.



Fasting for weight loss? Here’s why scientists say it works long-term

(Supersize Vs. Superskinny: Season 2 Episode 5)


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