Easy Diet Analysis
August 13, 2013
Intermittent Fasting – Part Two
September 3, 2013

Intermittent Fasting


Diets come in and out of fashion quicker than hipster trends.  The cabbage soup diet, the master cleansing diet, grapefruit diet…people will try the most ridiculous things to lose weight.  One method of eating which has gained widespread popularity recently is intermittent fasting, unlike other dieting trends – it’s here to stay.

Recently intermittent fasting (IF) has got a lot of media exposure, from celeb endorsements to BBC documentaries, everyone who’s anyone is fasting.  Naturally, through books, websites and magazines people have interpreted IF differently and turned it into a money making machine.  Most of the resources I’ve found on the internet are selling a product – therefore giving biased information and over complicated methods.  In this article I’ll try and clear things up and show you just how simple and effective intermittent fasting can be.


What is intermittent fasting?

Unless you’re a secret sleep-eater, you will already be inadvertently fasting on a daily basis while you sleep.  Intermittent fasting is simply extending these fasts and making them more regimented.  The duration of these fasts can be manipulated, and the number of meals you eat during your eating ‘window’ is open to interpretation.

The three most popular methods of fasting (which will be explored further in part 2) are;

‘Lean Gains’ – daily fasts of 16-18 hours followed by a 6-8 hour eating window, created by Martin Berkhan

‘Eat Stop Eat’ – normally one or two 24 hour fasts per week with regular calorie consumption for the remainder of the week, popularised by Brad Pilon.

‘The Warrior Diet’ – 20 hours of fasting OR ‘under eating’, followed by a 4 hour feed, designed by Ori Hofmekler

Who is it for?

Whether you’re trying to lose weight, gain weight or just generally live a healthy life, periods of fasting can be useful for anyone.  In my experience fasting provides a certain amount of freedom and flexibility, after being chained to the traditional six meals per day approach for a number of years – only having to plan for two or three meals can be refreshing.  The convenience factor is especially welcomed in an office environment – no more worrying about sneaking a snack in or carrying around boxes of putrid tuna.

How Does Intermittent Fasting Work?


Eating less frequently normally leads to consuming fewer calories overall.  This happens via two mechanisms;

Less hunger – Eating fewer meals per day has been shown to increase satiety and a general feeling of ‘fullness’ (Leidy et al. 2010).  So for most, the more often you eat, the hungrier you’ll potentially be.  Less frequent, larger meals seems to keep people fuller for longer (Cameron, 2010).

Less opportunity to eat – Following the ‘Eat-Stop-Eat’ template (2 x 24 hour fasts per week) will automatically lead to a 25-30% reduction in calorie consumption per week; it’s not hard to see that following this, even for a short period, could lead to some fairly drastic weight loss.  The same can be said for the daily fasts – people will be less likely to consume excessive calories over an 8 hour period, compared to the ‘normal’ 16-17 hours (unless you really try of course).

Eating less frequently, and therefore consuming less calories overall, means there is less readily available energy to fuel your body, thus creating the ideal environment to use stored energy as fuel.  This is accelerated when training in a fasted state – there is little available glucose or glycogen, forcing your body to use the energy stored in your fat cells.


Hormonal –

The body responds differently when in a fasted state than when in a fed state; manipulating these changes is important to the success of any intermittent fasting protocol.

Insulin sensitivity – this is probably the most important factor that changes during (or after) a fast (Halberg et al. 2005, Harvie et al. 2011).  On a very basic level, the higher your insulin sensitivity, the more likely you are to lose fat and, in most cases gain muscle.  
When eating during this period of heightened insulin sensitivity your body will process the nutrients at a much more efficient level – specifically sugar.  People with low insulin sensitivity (also known as insulin resistance) will not deal with carbohydrates well, and will be more likely to store the energy as fat.
This effect is heightened if a person trains during this fasted state (Van Proeyen et al. 2010).
Fasting=↑ insulin sensitivity=fat loss
Fasting + training=(↑insulin sensitivity)x2=(fat loss)x2  (this is a slight exaggeration, but you get the idea)
Growth hormone(GH) – GH stimulates cell repair and regeneration, promotes the use of stored fat as energy and increases protein synthesis…it’s pretty damn important. Periods of fasting have been shown to increase GH levels (Ho et al. 1988).
Muscle Loss – One of the most common myths I hear against IF is that fasting will result in muscle loss.  This tends to stem from the idea that a steady stream of protein (and therefore amino acids) is required to gain or maintain muscle – this in itself is a myth.  Protein is digested and released into the bloodstream at a very steady rate, therefore each solid protein meal will provide a slow release of amino acids into the blood over a number of hours.
Starvation Mode – Another popular myth is that any length of fasting causes your metabolism to grind to a halt.  Causing your body to enter starvation mode, holding on to energy and body fat to compensate for a drop in calorie consumption.  I wrote more about this in my previous Meal Frequency post, but to summarise…it’s flawed logic.  During the first 24 hours of a fast your metabolism actually INCREASES, and a much longer term fast of roughly 5 days would be required to cause any significant change.
Frequent Eating=Increased Metabolism – I’ll refer you back to my Meal Frequency post again.  This argument is again based on flawed logic – any effect food has on your metabolism is due to the total number of calories you consume, rather than the frequency at which you consume them.
As you can see there are numerous benefits to intermittent fasting – easy, no drama fat loss, better hormone profiling and probably longer life expectancy.  These benefits, coupled with a more practical way of eating throughout the day makes me a huge advocate.
In the next post I’ll go into more detail on the different methods of fasting and give some details on how to structure your day and fit in your training.
Part two can be found here