Lifestyle, Nutrition

What Is Intermittent Fasting? The Ultimate Beginners Guide.

Although intermittent fasting has only recently been making headlines as a way to improve overall health and wellbeing, it is important to note that fasting is a tradition that is as old as humanity itself.

Our ancient ancestors lived a hunter-gatherer lifestyle which meant that on occasions they went without eating for long periods of time. They didn’t have the convenience of nipping down to the local dairy whenever they felt peckish. It is only in our recent history that we have evolved to be constantly eating.

To get started with intermittent fasting you don’t have to change what you eat, how you eat nor whom you eat - you only have to focus on when you eat.

It starts by breaking up your day in to two segments – an eating segment and a fasting segment. An beginners approach to fasting would be to have an equivalent eating and fasting period each day, meaning having a 12 hour window in which you allow yourself to eat, followed by a 12 hour window in which you don’t.

This is the most basic form of intermittent fasting.

From there you can go on decreasing the eating segment and increasing the fasting segment, passing through some of the more popular methods:

16/8 – This is one of the most common versions of IF, whereby fasting is done for 16 hours, followed by an 8 hour window of eating. In practise it is quite easy to incorporate into your day because, say you were to eat between 12pm and 8pm, it only really implies skipping breakfast.

18/6 – This incorporates an extra two hours of fasting for those who feel adapted to a fasted state and want to push the benefits a little further. In practise this would mean restricting your eating between say 2pm and 8pm.

OMAD – One Meal A Day, also known as 23/1 is where you allow yourself 1 hour a day to eat. Targeted towards those who are fully adapted to fasting and looking to stay in a calorie deficit – as it is pretty hard to eat enough calories in an hour (healthy ones at least) to be in a surplus.

Then there are segments which are set at a weekly level, where by eating / fasting periods occur across certain days as opposed to set hours. A popular method is the 5/2, whereby for five days per week you eat as normal, then on the other two days you reduce your calorie intake to a quarter of your daily needs, which works out to be around 500 calories. You chose the days to fast and the days to eat, as long as the two fasting days are not consecutive.

Then there are longer fasts, lasting anywhere from 36 hours up to 72 hours and beyond (the longest recorded fast is 382 days!).

Why Would Anyone Want To Do That To Themselves?!

Understanding what happens during fasting can help us to see why anyone would want to do it in the first place.

0-8 Hours

For the first few hours after you eat your body is busy using up all the glucose that was released in to your bloodstream from the food that you ate, giving you the energy needed to power through your day.

Once you pass the 8 hour mark, the glucose levels in the blood begin to dip. This is a time where you might start to feel a little hungry, tired, or perhaps a few food cravings. Not to worry, as these symptoms tend to pass pretty quickly.

8-16 Hours

After around 12 hours, the body will start to look for energy elsewhere. It will start by tapping in to stored sugars in the liver and muscles, and the result of this will be a stabilizing in blood sugar levels.

Also around this time will be when the body starts switching over to early stages of ketosis, where it transitions from burning carbs (sugars) for fuel and instead begins to use stored body fat.

16-24 Hours

16 hours in and the rate of ketosis begins to increase. This is where your liver converts stored body fat in to ketone bodies, which will replace glucose as the fuel source for the activities in the body.

Now that you’ve made it this far, there might be a few benefits that you will start to experience. Such as:

Reduced appetite – this is due to the consumption of ketones in the body, which suppress appetite. Any feelings of hunger that you had previously should actually start to subside now, and should generally decline further as the period of fasting lengthens.

Boosted brain function – an increase in a protein called brain-derived neurotrophic factor (BDNF) can encourage the growth of new brain pathways, while enhancing learning, memory and coordination, and boosting your mood.

Fat loss – as ketosis gets underway your body begins eating in to your fat stores. Additionally, at this point in the fast your levels of ghrelin may decrease, which is a hormone that makes you want to eat a lot, and insulin levels will stabilise which in turn help to prevent food cravings. Combined, these factors contribute to prevent over eating, making it easier to stay within a calorie deficit each day which in turn leads to weight loss.

24-72 hours 

A day without food and your digestive processes are mostly through. The body now has the time and energy to focus on repairing itself, recycling old damaged cells, proteins and tissues and reducing inflammation. Here’s how:

The cells in the body turn on a process called Autophagy. This is the cells way of responding to mild stresses, which can be caused by things like exercise or in this case longer term fasting. Autophagy causes the cells to look at whatever is broken, old or due for replacement. They then recycle the old cells and turn them in to new ones.

The body supplements this process by dramatically increasing levels of human growth hormone (HGH). An increase in HGH can lead to increases in muscle mass, faster muscle repair and can also speed up the healing process for wounds and more serious injuries. In fact, HGH is so effective that it is considered doping if professional athletes were to take supplements of it.

Also, as the body is now running on ketones, you may notice major improvement in cognitive performance, mental clarity and an overall sense of wellbeing and energy as time progresses.

72+ Hours

Once you’ve gone this deep in to the fast, the processes of autophagy are in full swing. Studies suggest that 72 hours of fasting can lead to an almost complete rejuvenation of the immune system by triggering stem cell production, creating new immune cells to replace the old ones.

Longer fasts can help the body to become more resilient to stress, and certain hormones that the body produces at this stage can have beneficial anti-cancer and anti-aging effects.

So Intermittent Fasting Is All Positive?

Eating regularly is a habit that we have build up throughout our lives and as with any habit that has been built up over a substantial period of time, the first few attempts at breaking it will probably be a little challenging. Some of the initial discomforts that you might experience when commencing a fasting regime are as follows:

Hunger And Cravings

This may seem a little obvious, but when you stop eating for a while you will eventually feel hungry. When hunger sets in, cravings start to dance around our heads like fruit flies around a full compost bin. While this doesn’t exactly feel great, it is useful to note that these symptoms generally subside as the body adapts to burning body fat for fuel.

Mood Swings And Irritability

Because fasting can cause an initial drop in blood sugar levels, you may feel some of the negative emotions that are associated with this change. Irritability, anxiety and a lack of concentration are all symptoms of low blood sugar that can accompany any first attempts at a fasting regime. Once your blood sugars stabilise and your body adapts, these symptoms should reduce.


These are common side effects of fasting that generally occur within the first couple of days. If you are pre disposed to headaches, this might be something that you notice more so than if headaches are generally something that you don’t experience. They tend to be mild and generally go away of their own accord. Also, depending on your caffeine habits, the headaches could also be a symptom of caffeine withdrawal for those who are fasting from coffee and tea as well.


Again with the low blood sugar theme, fatigue and weakness can set in as a result of a drop in blood sugar levels. This should however pass pretty quickly and you can even end up feeling less tired and more energised as you become more adjusted to a fasting routine.


As intermittent fasting is reducing the amount of time that you allow yourself to eat, it tends to reduce your overall consumption of calories.

It is vital to eat a well-rounded, balanced diet while practising IF to ensure that your body is not missing out on nutrients. If you fast regularly, or for an extended period of time, and you don’t replenish your body with what it needs, this could result in malnutrition over time.

So Should I Fast Or Not?

Like most things in this world, IF can be beneficial for some and harmful for others. If you have a pre existing medical condition or are currently taking medications, it would be wise to have a chat with your doctor to see if fasting is the right approach for you.

As discussed above, there are short term and long term benefits associated with fasting, and there are also discomforts and challenges that may arise. If at anytime fasting is just making you feel miserable, take it as a sign that it might not be the right approach for you at this moment in time.

Fasting has been used by many as a tool to improving their general health and wellbeing, however it is not the only way to achieve a healthier state. Regular exercise, good sleeping patterns, managing stress, and a healthy, well balanced diet are all methods that you can readily employ to promote an improvement in your health.

If you are keen to give fasting a go, here are a couple of tips to make sure that you are following the correct protocol:

Stay Hydrated

Drinking plenty of water is paramount during a fast. Also of importance is to monitor the electrolyte balance in your body. If you are prone to cramps or are sweating a lot throughout the day, make sure that you are replenishing the minerals lost by adding a little sea salt to water or by taking a no-calorie electrolyte supplement.

No Snacking

Fasting means abstaining from eating. The idea is to reduce your calorie intake to zero, or to a minimum level whereby you encourage the body to enter a state of repair as opposed to a state of digestion.

There are some exemptions however around low – zero calorie beverages, such as black coffee, tea and so forth (with no added sugar or milk). Anything with too many calories will break your fast and negate many of the benefits you otherwise might receive if your stomach was resting.

If you feel like giving intermittent fasting a go, then all power to you. It only makes it all the more important to eat healthy foods outside of your fasting window to maximise the nutrition that you are receiving when you allow yourself to eat.

Browse our range of delicious, healthy, ready made meals today and refuel the right way.