What is Intermittent Fasting?

Nutrition at osteopathy West London
By Hannah E. Whitcombe

Intermittent fasting (IF) is a style of eating where one intermittently enters a period of fasting between meals, whether it be for several hours or even days. This is said to rest the system and bring about numerous health benefits to the individual; weight loss, better sleep and improved concentration to name a few!

Nutrition at osteopathy West London

Fasting is the period we enter several hours after a meal, when glucose is low, and is said to be the healing and repair state for the body. This usually occurs overnight, during the period between our last meal of the day and our first meal the following day, hence the term ‘breakfast’ literally meaning ‘to break fast’. Therefore, all of us are intermittent fasters to an extent, but is this brief period of overnight fasting enough for us to harness the benefits that intermittent fasting has to offer?

Historically, our ancestors had to put in some serious effort to bring a meal to the table via hunting, gathering and slow methods of food preparation, which naturally led to fewer calories and longer periods of fasting between meals. Nowadays, we rarely go a full 8 hours before breaking our nightly fast with our first meal of the day. Besides which, we are consuming far more calories during the day, meaning that we never actually enter a true period of fasting and are consuming way more energy than we are able to burn. This is reflected by modern health concerns such as obesity and diabetes.

Are there any proven benefits?

Though the most obvious benefit of fasting may be weight loss, it has far more to offer, with the latest research revealing that it may even be able to slow down the ageing process and prevent diseases such as cancer, diabetes, arthritis and heart disease!

To understand how fasting leads to weight loss we must first understand the fed and fasting states of the body. The fed state begins at around the time of eating and lasts for several hours after a meal, in this state insulin levels are high and any excess energy is stored as fat. The fasting state however, begins 8-12 hours after a meal, at which time insulin is low and fat burning is at its peak. This is a great reason to exercise in the morning before your first meal, especially if you wish to loose weight and reduce overall body fat! Furthermore, during a fast,  due to limited available glucose, fat is broken down for energy. 

But how can going without food slow down the ageing process and reduce chronic disease?

Well, simply put, when we enter a period of fasting, we are no longer using energy to digest and metabolise food, allowing the body to enter ‘heal and repair’ mode. During this time, harmful substances that promote inflammation and lead to chronic disease are broken down and eliminated by the body.

In addition, when fat is used for energy during the fasting state, it is known as ketosis, a process resulting in the production of ketone bodies.  These ketones are a primary fuel for the nervous system and are able to nourish the brain, which is one possible explanation for the increase in memory and cognitive function during and shortly after a fast.

Therefore, the benefits associated with intermittent fasting include (but are not limited to);

Weight loss
Reduced chance of developing diabetes
Improved concentration
Better sleep

Management of headaches
Reduced inflammation

• Cancer prevention
Increased longevity

What are the different schedules most typically used in intermittent fasting?

16:8 (16-hour fasting): this is by far the easiest method and requires that you consume all of your daily calories within an eight-hour eating window. Simply put, having your last meal of the day at around 7pm will mean that your breakfast will be at around 11am. During the morning, it is fine to have black tea or coffee to keep you going and is highly recommended if you plan to workout during this time.

The time that you choose to fast is flexible and dependant on your own schedule, so if you have your last meal later in the day, just adjust your own fasting window accordingly.

24 hour fasting: often referred to as the ‘hero fast’, this method requires you to abstain from food for a full 24 hours and is therefore slightly more challenging. It is often popular to do on a Monday and used as a good way to kick start the week. Again, consuming beverages without any calories such as tea or coffee are fine and encouraged.

The 5:2 method: this is a popular method used by persons wishing to reduce their overall body weight and is best used in conjunction with other diet and lifestyle alterations.The 5:2 approach requires that you to reduce your calories for two days per week to around 5-600 calories and is often referred to as the two-day diet! It is recommended that this be used in conjunction with increased exercise and proper nutritional adjustments.

3-7 day water or juice fasting: this involves abstaining from food for 3-7 days. The most extreme approach to this method is a water-only fast and can be quite challenging to the new and seasoned faster alike. A more gentle approach may be a juice fast, which may be enough of a detox for the average person. The alternative, or middle way, can be coconut water fast, which offers a slightly more nourishing alternative to a water-only fast.

Often during a fast, the first 1-2 days are extremely challenging and hunger will be experienced, however, people often report that hunger completely goes away from the third day onwards making it difficult to even end the fast! If for any reason, you are unable to begin eating again, it is important to consult your healthcare provider.

This method of fasting requires discipline, not only for the fast period but in how you enter and exit this period. For 1-2 days prior, it is recommended that you start to eat lightly and avoid sugary or processed foods, likewise, when you are ready to break your fast, avoid processed foods and start with small plant-based meals.

Fasting for a period of longer than 7 days is not recommended without medical supervision, though some residential fasting programs support a fast for up to, and sometimes beyond a period of 30 days!

Are there any drawbacks?

Fasting is an amazing thing to do for your health, though it is important to be aware of the side effects before you begin. Furthermore, if you are taking medication, have a history of an eating disorder or have been given a diagnosis of any kind, it is important to consult an experienced healthcare provider before you begin.

Fasting is contraindicated in pregnancy, breast-feeding mothers and persons with a recent alcohol or drug related issue.

The main side effects likely to be experienced are;


To mitigate the side effects mentioned above, ensure that you stay hydrated and consider the use of enema or colonic irrigation before, during or shortly after your fast.

Getting started?

For most, the thought of fasting will arouse some anxiety, therefore, it is recommended that the daily 16-hour approach be tried and tested before attempting something more challenging.

However, if 16 hours is too much at first, start by delaying your first meal of the day until you feel that 16 hours is achievable. At first, hunger will be an issue but as you become more accustomed to your fasting schedule, these symptoms will subside and you will hardly even notice that you are fasting, in fact it will just become part of your usual routine! It is said that it takes around 21 days to form a new habit, so stick with it, it will become easy!

To progress to an extended period of fasting, the key is to prepare well and plan your days so that you don’t get distracted by inconvenient pangs of hunger, often exacerbated by boredom. It is surprising how much time preparing, cooking and eating takes form your usual day, so you may find yourself with several more hours to fill. Gentle forms of exercise such as walking, swimming and yoga, are often recommended, though be careful not to overdo it, especially if you are new to intermittent fasting. Massage and meditation are also great ways to pass the time and maximise the benefits of a fast.

If you’d like to speak to a member of our team, please don’t hesitate to get in touch. You can call us on 0208 088 0614, alternatively you can book a FREE consultation with our at osteopathywestlondon.com/booknow

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