Archive for September, 2013

Exercise and intermittent fasting (the 5:2 diet)

So have you heard about the 5:2 diet fad? 

Well, although it’s been taken up pretty quickly after some publicity in an U.K. television special, it’s not really a fad.

Intermittent dieting has been around for many years and is based on research on eating patterns in part of Asia.  As with a lot of seemingly good ideas, it takes quite a while for sufficient research to come to light to make the concept suitable for public acceptance and subsequent use.  So whilst the concept isn’t a fad, this new incarnation of it may well be so… we’ll know in five years or so I guess.

So what is it? 

In practical terms the 5:2 diet is a version of intermittent fasting where for five days a week you eat a normal diet and for the other two days you restrict your calorie intake to 500 calories for females and 600 for males – that is one quarter of the normal calorie requirement for the average person.  The two days of ‘fasting’ are not to be consecutive.  The idea is that you can eat whatever you want on the other days, but really, whilst ‘in versus out’ is a bit simplistic, it’s still a basic rule.  A normal healthy balanced diet should be the focus of the rest of the week.  During your fasting days you can eat all your calories at once or spread them out.  The research hasn’t been done on that yet.

How Does it Work?

Scientists have known for the last 60 years that controlling calories and eating only strictly healthy food (no sugar, low fat, small meals) can prolong life span by up to 40% in mice.  How that translates to humans is problematic but there is anecdotal evidence that it does.  There is even limited scientific evidence that indicates fasting reduces levels of IGF-1 – a hormone partly responsible for quick growth and development in humans and also partly responsible for aging as we get older.  Limiting this hormone in your system by fasting encourages the body to go into a repair type mode where the body utilizes body fat to repair and prepare for starvation mode.  The fact that you eat normally again the next day staves off starvation and you return to normal maintenance mode.  Over time significant reductions in blood pressure, cholesterol and blood sugar have been recorded in most participants in the few studies so far.

So can you still exercise on a diet like this?

Well… there’s been no work done on this that I can find.  But what I do know is that diet without exercise will result in muscle loss – and I mean intense exercise is required to maintain muscle mass, not just a run around the block a few times a week.  You can read my upcoming blog about the benefits of intensity to see what I mean.  So can you do this?  Exercise and fast?

I’m about to find out…

Before I run my PT clients through training programs I devise, I always run myself through them for at least four weeks.  I subscribe to the theory that I shouldn’t make people do things I’m not prepared to do, so I make sure what I give people to do is do-able.  At least by me… So the same goes for the dietary advice I give.  I live by my high protein, low carb meal plan.  I basically live on eggs, milk, meat and vegetables with some occasional fruit yoghurt and nuts thrown in.  So I’m going to see if I can maintain my exercise plan whilst on a 5:2 diet.

I’ve already started…

I started Tuesday.  I plan Tuesday and Thursday to be my ‘fasting’ days and I’ll stick to my normal diet on the other days and see if I can keep going.  My first day was fun… not!  I’ve been busy – really busy – some days where I actually don’t eat until dinner but I’m so busy I don’t notice it.  When you plan to do this however, it’s a different matter.  I woke up thinking about food and did so all day.  Those who know me know that I’m normally not that worried about being hungry.  But I thought about it all day.  I decided that I’d prefer not to start up the hunger cycle by eating too early in the day.  I remember a study on POWs in the second world war where they asked survivors about how they spread their rations from issue to issue.  The two main techniques were to either eat very small portions and spread the food out, or to wait until you couldn’t cope any more and eat it all at once.  What they round out was that those who waited and ate it at once were more likely to have less health problems and more likely to live.  So based on that study and some other suggestions for coping with this diet I waited until after my normal lunch time to eat my two boiled eggs and spinach salad.  I then waited until about 8pm for my dinner of baked flake and vegetables.  Plenty of vegetables to make up my 600 calories.  About 2 1/2 full cups of mostly green iron rich vegetables like broccoli, brussel sprouts and broad beans.

I did my usual exercise – 25 minutes of super sets and 20 minutes of high intensity interval training and felt none the worse for my lack of food.


I woke up Wednesday and was very tired.  I didn’t sleep as well as normal and woke up feeling very sluggish.  I wasn’t unusually hungry like I thought I’d be but I felt exhausted.  So exhausted I used the day as my weekly rest day.  I sort of felt like I was sick and couldn’t exercise.  I ran a couple of PT sessions and had trouble standing up for 45 minutes!

But come on… it’s the first day and there’s bound to be some adjustment to something new like this.  Tomorrow is my second day of fasting so we’ll see what happens.  I’ll keep you informed!

It’s getting late… better chow down!