Intermittent fasting is a fairly controversial method because many people associate ‘fasting’ with ‘starving’ when they are not the same thing AT ALL. I have been a follower of fasting for health for a while now but had thought that it was, again, far too un-sexy to gain any sort of media momentum. It turns out I was wrong! In August 2012, BBC’s Horizon did an entire episode on the concept of fasting and how it is used by people across the world to control weight and improve health. After the airing of this TV program my email inbox went crazy with emails from my followers asking if I’d seen it, saying that it covered a lot of the things that I am always preaching to them. It is brilliant that many more people are becoming aware of this method as it’s been around for a very long time.
I first heard about the concept from a highly respected Chinese herbalist and acupuncturist who is in fantastic shape and who looks a good 15 years younger than he is. He fasts regularly (usually at least once a month) for the health benefits he believes it conveys. When I first heard about it I thought to myself, “what’s all that about? Why does he do it?”. Like many who have been educated according to conventional ‘wisdom’, I thought that his body’s starvation response would kick in and so this method would be counterproductive. The starvation response occurs (apparently) when we cut our calorie intake so much that our bodies start to store fat rather than burning it. Furthermore it starts to use protein, such as muscle, for fuel instead. But this clearly wasn’t happening to this chap as he was a slim, vital, picture of health.
My curiosity tickled, I decided to look into intermittent fasting further and found, to my surprise, that a huge amount of research had been carried out into the benefits over the years (and I don’t just mean the last 10-20 years either but more like the last 90 years). So I looked through all kinds of studies and journals and I stumbled upon a guy called Brad Pilon. Although intermittent fasting has been around for centuries, Brad has championed this way of eating, along with a few other ‘renegades’ (I use this term ironically and you will see why below), over recent years and is responsible for thousands of people being introduced to the fasting way of life. I was very sceptical at first, but what I found was very interesting.
The concept behind intermittent fasting actually stems from Palaeolithic times. Our caveman ancestors didn’t have three square meals a day. In fact, they would go frequently go for long periods without food until they captured their prey, when they would feast. Fast forward to modern day life and it’s clear to see we live in a state of constant feast, especially if we commit to the idea of having to eat around every 3 hours, as most of us do. So in evolutionary terms, the evidence seems to suggest that our bodies are actually built for more sporadic eating patterns than we follow today.
But, before you start panicking that you are going to have to live on water and barley sugars for 48 hours, don’t. Most ‘intermittent’ followers, including me, will only fast for 16-24 hours. And even this isn’t as bad as it sounds because the large proportion of this will happen while you are sound asleep. You eat your dinner in the evening, fast through the night while you sleep and the next morning until early/late afternoon the next day and that’s it. BUT once you’ve finished the fast it is important then to carry on eating as normal. Don’t be tempted to have a binge as you will undo all of your good work. Of course you can fast at times that suit you; you don’t have to follow this schedule, but the evening fast works particularly well for me and many other intermittent fast followers.
How Does It Work?
You could be forgiven for thinking that fasting is simply about creating a calorie deficit on the days that you fast. This is only part of the process. Our bodies are very savvy and several mechanisms combine to deliver the many benefits of fasting.
A calorie deficit is, of course, helpful for fat loss: if you eat fewer calories than you need to function you will start to burn fat stores – simple maths! A low calorie diet over the course of seven days can be quite a mental battle, but with intermittent fasting you get the benefit of a week’s low calorie diet in the space of two 16 to 24 hour periods. If you fast through the night you will, more than likely, be asleep for the majority of the fast, which makes the whole process a little easier. A 24 hour fast is a little bit more difficult, but certainly not impossible. I know of people who fast for long: take religious fasting, for example. If you are new to this, however, stick with 16-24 hoursat first to see how you get on.
With any diet there is the problem of adherence and this is where intermittent fasting comes into its own. One study found that those who followed intermittent fasting were able to lose weight and maintain their new weight 12 months later. But there are other health benefits to fasting as a way of life and much research points towards increased life expectancy and disease prevention.
As well as the calorie deficit, intermittent fasting helps to manipulate our hormones, in particular insulin and human growth hormone. I’ve already spoken about how insulin can be detrimental if we have too much circulating within our body as it makes it harder to burn fat and easier to store excess calories as fat. High amounts of insulin in the body also cause the level of human growth hormone to decline. Growth hormone allows us to release more fat so that it can be used as energy. If you’ve only got a small amount of growth hormone in your body, fat loss will be an epic struggle. By using intermittent fasting, you create both a calorie deficit and trigger your body into regulating the right balance of hormones for fat loss. Happy days.
While we’re on the subject of insulin again let me back all of this up with some science. In 1993, a study in the American Journal of Physiology found that more fat was used as energy as a result of intermittent fasting in young men and this was thought to have been caused by a drastic drop in insulin over a 24 hour period.
Another study in 1994 in the Journal of Clinical Endocrinology went on to back up the previous study with 8 female cyclists. They found that blood insulin was low throughout the 72 hour fasting period and that these women lost a significant amount of weight at the end of the experiment.
In 2005, the Journal of Applied Physiology published a study on the effect of fasting and the impact it had on insulin in 8 healthy young men. These men were told to fast every second day for 20 hours over the course of 15 days. The men were told to stick with their normal exercise habits, to maintain their usual macronutrient mixing of their meals, and to eat sufficient quantities of food on the non-fasting days to ensure that their body weight did not change during the experiment. After two weeks of intermittent fasting, body weight, body fat percentage and muscle energy stores were unchanged. In contrast the above studies, insulin levels were unchanged, although insulin activity did increase. None of the men lost any weight which means that the improvement in insulin sensitivity is not due to a restriction in calories but the bouts of fasting. This lends support to the idea that periodical fasting is beneficial for insulin sensitivity.
Insulin sensitivity, in simple terms is the increased ability of our muscles to allow energy in, which prevents further energy being stored as fat. As you can see, we therefore want to be more insulin sensitive so that we can deal with sugar and carbs better. If we have poor insulin sensitivity, when we have a carb heavy meal or our favourite desert our insulin level rises sharply, but unfortunately our muscles are unable to soak up the extra glucose (energy), either because they are already full or rubbish at allowing this energy in.
I hope that makes sense, it’s a tricky subject to get your head around, but all you really need to know is that fasting will help improve the transportation of energy to the muscles. In addition to fasting, you mustn’t forget that exercising also improves insulin sensitivity.
When Should You Use Intermittent Fasting?
I recommend using the 5:2 approach: choose 2 out of the 7 days of the week to fast for anywhere between 16-24 hours, making sure they’re not back to back days. How often and when you fast is really down to you, but I strongly advise you not to fast more than twice a week or longer than 24 hours as your hunger will increase dramatically and it will start to become a chore, increasing the chances of you knocking it on the head.
If you are completely new to this concept, rather than jumping straight in at the deep end, I recommend you start with an induction phase for two weeks. This simply involves reducing the “feeding window”. At the moment you might eat anywhere between 8am in the morning to 8 or 9pm in the evening. I suggest you try to reduce this window to 8 hours to start with, which means you will be fasting for 16 hours. This will give you chance to see how you cope with fasting and help you to distinguish between hunger and cravings. If you feel that intermittent fasting works for you after this induction phase then you may reduce the feeding window once again, so that your fast is longer in duration and more in line with the 18-24 hours that I recommend.
Results and Benefits
In terms of weight loss results, you can expect to lose 1 or 3 lbs. a week on the 5:2 method but this of course is dependent on your current weight and fat mass. Intermittent fasting also gives your digestive system a rest which, for most of us, can be a little overworked.
I am aware that not all of you will be trying to lose weight. There are still health benefits to be had from adopting this practice. Research suggests that fasting helps to slow the ageing process by reducing the production of a growth hormone called IGF-1 which accelerates this process and reduce the chances of many age-related diseases as a consequence.
Intermittent fasting also reduces cell damage and inflammation through a reduction in oxidative damage and cellular stress. A better way to understand this is if you imagine a bicycle left outside for months on end. It’s likely that this bike will rust, right? But if you bring the bike indoors once in while you give it a better chance of keeping the dreaded rust at bay. The same sort of things occurs with our body when we constantly eat, so it pays to give it a rest by fasting, which will then prevent it from ‘rusting’.
Another benefit of intermittent fasting is that it gives you a sense of freedom. As we’ve already said, low calorie diets can be a mental battle. With intermittent fasting, you won’t have this on-going battle. Just a 16 to 24 hour period and then you’ve finished and can go back to your normal diet. You don’t need to count calories, you don’t have to think about what you’re going to eat; you just get on with your day.
Before you get carried away with the brilliance of it all, you should know that there are lots of people who frown upon intermittent fasting, suggesting that fasting is simply starving yourself and will ultimately slow down your metabolism preventing you from burning fat. Fortunately the science bods are on top of this. There have been many studies into fasting over the years and not one of them has noted a decline in metabolic rate or an increased storage of fat as a consequence. I’ll highlight a few, below.
The University of Nottingham found that when they made 29 men and women fast for 3 days, their metabolic rate did not change. This is 72 hours without food. So much for needing to eat every three hours to keep your metabolism going!
In another study performed at the Pennington Biomedical Research Centre, men and women who fasted every other day for a period of 22 days experienced no decrease in their resting metabolic rate.
In addition, a study published in 1999 found that people who were on very low calorie diets and on a resistance exercise program (i.e. lifting weights) did not see a decrease in resting metabolic rate and these people were only eating 800 Calories a day for 12 weeks!
Let’s keep this going. In another interesting study published in Obesity Research, women who ate half the amount of food that they normally eat for three days saw no change in their metabolism.
Room for one more? In a study published in 2007, ten lean men fasted for 72 hours straight. At the end of their fast their energy expenditure was measured and found to be unchanged from the measurements that were taken at the beginning of the study.
So what happened to the so called ‘starvation mode’ (remember, the idea that when we don’t eat our body flicks a switch and decides not to burn any fat, but instead store it and use our muscles as fuel)? No matter what the guy you know down the gym tells you the science says that starvation mode doesn’t exist for this short period of time. We’ve got at least a 72 hour window where our metabolism is unchanged while we fast.
Indeed, many of the fasting-doubters go further than challenging fasting with the ‘starvation mode’ argument by adding that we actually should be eating smaller meals more often to raise our metabolism. This notion stems from the thermic effect of food which, simply put, means that when we eat our body has to work to digest the food, which causes a SLIGHT increase in metabolism. Does this really mean that we will see significantly beneficial effects from eating more often? I don’t think so.
As well as the practical issues of stopping to eat 5 or 6 times during the working day, if we eat more often we then face the risk of eating too many calories if we aren’t careful. For the average working person this becomes a pain in the ass and doesn’t work in the real world. If you’re exercising heavily several times a day, you may need to eat more often to supply your muscles with energy, but for most of us, including me, it’s not advantageous in losing weight or staying in great shape.
Intermittent fasting tips
Intermittent fasting is gaining momentum as a lifestyle choice, especially among those who already follow the Paleo diet. However, that doesn’t mean that you should jump in at the deep end and start fasting for days at a time. There are many difference approaches to intermittent fasting, but I suggest you keep it simple and follow my guidelines below:
- start with a 16 hour fast first to make sure you can cope and your life doesn’t fall apart;
- don’t fast on back-to-back days;
- drink more water. With the lack of food comes a lack of hydration as we get a lot of our liquid from the food we eat;
- you can still exercise during a fast, but keep it short and sweet. Endurance activities are a big no whilst fasting;
- make yourself busy. The busier you are the less time you’ll have to think about food;
- fast through the night to make your life easier;
- if you are new to this, don’t try to combine low carb and intermittent fasting at the same time, you will not enjoy it!
A Word of Warning
Both carb cycling and intermittent fasting are useful weight control tools but they are not a quick fix. In terms of your health, you can’t beat a diet of lean meats, fish and plenty of fresh fruit and veg. This should always be at its foundation. If you fail to improve your diet first then your hormones will still be out of shape and no amount of carb cycling or intermittent fasting will help you.
So, if your diet is a mess to start with these methods are best left for the future. Instead your goal should be to follow a healthy diet and to make that a habit first. Check out my Nutrition Basics to refresh yourself. If you can do this for several weeks you will improve your health and, consequently, your body shape. If you still need to drop body fat after this, then is the time to introduce carb cycling or intermittent fasting.
When you’ve achieved your ideal body shape, bring in the 80/20 rule. This is the rule I use and it goes like this: 80 per cent of the time, eat clean (lean meats, fish, veg, fruit, etc) and the other 20 per cent allow yourself a bit of freedom and eat the foods that are perhaps not so good for you. It will make your life more enjoyable, as you have to give yourself a few treats every now and again, right?!