How to: Intermittent Fast

I’ve been intermittent fasting now since August 2012 and am pleased to say I’ve successfully made it an everyday (or weekly) part of my lifestyle.

So much so, a few people have asked for my advice on how to get started and how to make it a part of their lifestyles.


I was first introduced to the idea of fasting from the Horizon Eat, Fast and Live Longer programme.  The present Mike Mosley went through a few different types of fasting, from 3 days in a row, to 2 days a week.  He decided he would do two days of fasting where he would eat 500 – 600 calories during his fasting period and eat normally the rest of the time.  He had water, tea and cup a soups to make up his calories.

There are a whole host of benefits linked to fasting.  And if you look at it simply, it’s how our ancestors evolved to eat:

  • periods of eating lots (where they’ve been successful in hunting / gathering


  • periods of fasting where food / animals were scarce and hunting /gathering weren’t as successful.

Fasting which has a whole host (mainly unproven!) of benefits:

  • Weight and fat loss
  • Increased Growth Hormone which helps your body to repair
  • Improved cholesterol
  • Reduced blood pressure
  • Reduced risk of contracting age related diseases like cancer and diabetes.
  • Improves insulin sensitivity
  • Reduces inflammation in cells
  • Improved mental well being and clarity
  • Your body slows down (my resting heart rate was 40 on one of my recent fasts as my metabolism had slowed right down)

See more detail of the benefits here: Mark’s Daily Apple: Benefits of Intermittent Fasting

Here’s a quote from the page above I quite liked:

‘Overall, fasting just seems right. It’s like a reset button for your entire body, presumably across a large spectrum of maladies and dysfunctions.  It puts your body into repair mode – at the cellular level – and it can restore normal hormonal function in the obese or overweight. Now, you don’t have to fast, but it’s definitely something to consider. ‘


I looked into fasting, and with the level of exercise I do (5-6 days a week), I decided I’d try an 18 hour fast, one day a week (on my rest day).  The first time I did it I stopped eating at 2pm and didn’t eat again until breakfast time the next day (8am).

It seemed to be fine (but I did drool a bit over my partners dinner that night!).  And then my brother Ewen suggested I try stopping eating at 8pm (after dinner) and not eat again until 2pm (the idea being that you sleep through most of your fast) and it seemed to work well for me.

So that’s how I continued to do it:

  • Intermittent fast: 1 day a week: 18 hours fasting: 1:6 days, 18:6 hours.
  • Stop eating after an evening meal at 8pm, fast until 2pm.
  • Drink unlimited water, green tea and limited coffee (1-2 cups a day)
  • Eat normally the rest of the time: appreciate food and continue to eat healthily.

I found that 18 hours was about right for me… the hunger came and went in waves, but I tended to find that I got really hungry an hour or two before I knew I was going to eat.  It can take a bit of will power not to eat anything at that time, but you just need to get your mind on something else and fill up with water or tea.

And I even found that I could incorporate my fasting into my travelling to go and come back from holiday.  I didn’t want to fast whilst on holiday – so I simply didn’t eat from the night before travelling until we arrived in Italy at around 2pm (and the same on the return leg).

I don’t have specific days of the week where I fast, but instead choose a day when I do no or small amounts of exercise (usually my rest days).  My rest days tend to be on a Friday or a Tuesday, so they tended to be my fast day once a week.


Intermittent Fasting has been surprisingly easy for me to do.  I usually eat 5-6 small portions of food a day and used to HATE to feel hungry, but now that’s changed.  I can handle hunger, and sometimes don’t even feel like eating when the fasting period is up!

I feel like when I do eat, I really appreciate what I eat, and think a lot more about eating good foods to fuel my body.  I’m less inclined to eat crap, but then I also think that I can eat whatever I want because I’ve fasted.

My energy levels have not been affected and I’ve still been able to exercise the way I’m used to.  I do find myself a little more hungry the day after fasting, but I guess that’s to be expected and I find I can plan for it by knowing that I can eat a little more to make up for it.

In the last 10 weeks since starting fasting, I haven’t lost any weight (but I don’t have any to lose), however I do know of someone who doesn’t exercise,  is fasting alternate days and has lost 13lbs in 4 weeks!

My body fat has reduced slightly from 20.7% – 20.2%, and my blood pressure has reduced from 116/69 to a low of 98/58 at it’s lowest 2 weeks in, to level off at 107/68.  (Blood pressure and weight have been things I’ve been keeping an eye on, as I don’t want them to get too low.)

Fasting has become a way of life for me.  I feel great physically, am still able to exercise and I feel  stronger mentally having been able to do it (fast and be hungry) and keep it up.


Now that I’m comfortable doing Intermittent Fasting, I’m incorporating it into my life 2 days a week.  I have chosen to do:

  1. A 24 hour fast from 8pm Monday night to 8pm Tuesday night.
  2. An 18 hour fast from 8pm Thursday night to 2pm Friday afternoon.

I’m making two changes to how I did it before: there are ideas that:

  • Your ability to burn fat increases in the later stages of your fast,
    so I have opted to do exercise at the end of my fasts too.
  • Caffeine can help boost fat burn too,
    so I’m going to incorporate coffee, green tea and exercise into my fasts.

Here’s how I’ll do it, I’ll make sure I’m properly hydrated and will do this:

24 hour Tuesday fast:

  • Stop eating at 8pm Monday night.
  • Drink plenty of water and green tea, and limited coffee (a chilled one at 8am).
  • Have 1-2 protein shakes with banana, peanut butter if I want throughout the day.
    (8am & 4pm Tuesday).
  • Do an easy run at around 6:30pm Tuesday night.
  • Start eating again 8pm Tuesday night.

18 hour Friday fast:

  • Stop eating at 8pm Thursday night.
  • Drink plenty of water and green tea, and limited coffee (a chilled one at 8am).
  • Do a high intensity intervals / weights session at around 6:30am Friday morning.
  • Start eating again 2pm Friday afternoon.

My next steps in my nutrition is to try to find out how to eat as healthily as possible (along the Smarter Science of Slim and Paleo for Athletes way of thinking) to fuel my exercise, body and life!

See more detail of my 2:5 day IF here


If you’re interested in taking up fasting as part of your lifestyle, then hopefully the above will help you.  My main tips would be:

  1. Try fasting out for a few weeks so your body has a chance to get used to it: try doing 1 day of intermittent fasting once a week for between 3-10 weeks to get used to it.
  2. Once you’re used to it, either increase the amount of hours you fast for, or add in another day.
  3. You could try alternate day fasting for increased weight loss, however you might want to read up about this first in this book: Alternate day diet: turn on your skinny gene
  4. Make sure you hydrate sufficiently and eat up to 600 calories if you want to (I choose not to on 18 hour fasts, and have protein shakes on 24 hour fasts).
  5. Play about with the times and duration you fast from and to, and do what works for you.
  6. Try not to binge when you can eat, and try to use fasting as a way to really consider what you put into your body to fuel it.
  7. Try not to see it as a ‘diet’ but as a way of life – think about how our ancestors would have lived: ‘primal’ / ‘hunter gatherer’ with periods of plenty and periods of fasting – all you’re doing differently is controlling when you’ll be hungry / eat.
  8. Monitor your weight, body fat and blood pressure to make sure you maintain your health whilst fasting.
  9. Read up on fasting on the links and books below for more information.
  10. Eat, Fast and Live Longer!


Other options for Fasting include:

Days per week:

  • 1:6,
  • 2:5,
  • 3:4, /4:3 (alternate day fasting 1:1:1:1:1:1:1)

Hours per fasting day:

  • 24
  • 18:6
  • 14:8
  • 12:10

For more information on fasting, check out the book and links below:


The Fast Diet by Michael Mosley, and
The Alternate Day Diet by James B Johnson.


My fasting page with lots of information:

The power of intermittent fasting BBC:

BBC: Horizon Eat, Fast and Live Longer programme.

The IF life:

Fast 5:

Marks Daily Apple: How to Intermittent Fast:

Lean Gains:


Have you tried Intermittent Fasting yet?

Did you have a great, transcendent, middling, or perhaps even an awful experience?  

Has it helped you to lose weight, lose body fat or become healthier?

Let me know how intermittent fasting has worked – or hasn’t – with your lifestyle in the comment section below!

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8 Responses to How to: Intermittent Fast

  1. Pingback: Intermittent Fasting 2:5 | Lorn Pearson Trains…

  2. Sue says:

    Just what I needed!! Thank you!!! Going to give it a go, will let u know how I get on xxx

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  6. Pingback: Horizon: Eat, Fast and Live Longer | Lorn Pearson Trains…

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  8. Pingback: 24hr Intermittent Fast Completed | Lorn Pearson Trains...

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