Intermittent fasting has become increasingly popular in recent years, but humans have been fasting for thousands of years. In prehistoric times, before we learned to farm, humans were hunter-gatherers who spent a large amount of time fasting when food was scarce. Our bodies evolved to be able to survive and thrive for long periods without eating. All the founders of modern medicine recognised the power of fasting and used it as a therapeutic tool. Paracelsus, the father of toxicology, called fasting “the physician within”. Fasting has many benefits on your body and brain, and research suggests it can significantly improve your health and extend your lifespan. 

How does intermittent fasting work?

Intermittent fasting is a method of cycling in and out of periods of eating and periods of fasting. Intermittent fasting is the umbrella term for this method of fasting, but there are multiple different ways that you can do this. Finding a format that works for you is key to doing intermittent fasting in a healthy, sustainable way. 

How does intermittent fasting improve health?

When you stop eating for a period of time, several things happen in your body:

  • Insulin levels go down
  • Blood sugar levels go down, causing your body to start converting glycogen into glucose to use as energy. Once your liver glycogen stores are depleted, your body will start to switch over to ketosis, where your body starts breaking down and burning fat stores for energy instead of glucose
  • Human growth hormone levels increase - this promotes fat loss and muscle gain
  • Gene expression changes - genes that support cellular growth and DNA repair are switched on, whilst genes that are associated with inflammatory processes such as amyloid plaque formation in the brain and the growth of cancer cells are turned off 

Intermittent fasting can help you to lose weight with relative ease when done appropriately. By eating fewer meals, you will naturally end up taking in fewer calories. This, combined with the fact that intermittent fasting lowers insulin and improves insulin sensitivity, increases human growth hormone levels and increases your metabolic rate, makes it one of the most effective ways to make progress with weight loss. 

 Aside from weight loss, there are many other benefits to intermittent fasting. Research has shown the anti-inflammatory effect and all the positive changes that happen in your body when you do intermittent fasting combine to reduce your risk of many diseases, including heart disease, diabetes and neurodegenerative diseases such as Alzheimer’s, and may even help you to live longer. Intermittent fasting is a relatively simple tool that most people can implement, with a multitude of powerful benefits. 


One of the key mechanisms that fasting supports is autophagy. Autophagy literally translates as ‘self-eating’ and refers to the body’s natural cleaning process of breaking down and destroying damaged cell components. This incredible process acts like a recycling plant inside your body, which serves to make your cells healthier and more efficient. The time it will take for your body to get into autophagy is very individual, but research suggests it takes longer periods of fasting (a minimum of 14 hours) for your body to use up most of your glucose and glycogen stores and autophagy to kick into gear. 

Migrating motor complex 

Another important mechanism that occurs during periods of fasting is the migrating motor complex in the small intestine. This is a peristaltic movement that helps to sweep bacteria, undigested food and debris through the small intestine to the large intestine for elimination. This process acts like a ‘housekeeper’ of the gut and helps to prevent bacterial overgrowth and food putrefaction. The migrating motor complex kicks into gear in a relatively short space of time, after about 90-120 minutes of not eating. Allowing plenty of time in between meals gives your gut the chance to complete several cycles of the migrating motor complex, which is crucial for good gut health. 

3 intermittent fasting techniques to try 

Time-restricted feeding

This refers to limiting eating to a certain window of time each day. The most common formats for this are 16/8 (16-hour fast, followed by an 8-hour eating window) and 18/6 (18-hour fast, followed by a 6-hour eating window), 20/4 (20-hour fast, followed by a 4-hour eating window). People doing the 18/6 and 20/4 methods usually find it easier to eat only one or two meals in that time period rather than trying to fit three meals and snacks into a relatively short space of time.


This involves fasting for a full 24 hours, once or twice a week. The easiest way to do this is to stop eating after dinner, and fast until dinner the next day. However, this can be challenging if you’re just starting out with intermittent fasting. I recommend starting with something more gentle and increasing your fasting window over time as your body adapts. 


This involves eating 500 calories two non-consecutive days a week. This format can be particularly effective for weight loss, but if you are not trying to lose weight then time-restricted feeding may be a better option so that you can ensure you get adequate calories into your feeding window in order to avoid weight loss. 

It’s important to note that intermittent fasting should not be a replacement for a healthy diet. You can’t fast your way out of a bad diet and using fasting as a way to mitigate the effects of a poor diet can create unpleasant physical symptoms as well as an unhealthy relationship with food. The core focus should always be optimising your diet so it is filled with nutritious whole foods, as close to nature as possible. Once this is achieved, intermittent fasting is like the ‘cherry on top’ of a healthy diet and lifestyle, and will amplify any of the positive things you already do to support your health. 

What does and doesn't break a fast?

Technically speaking, anything that contains calories will break your fast. This includes any food (even low-calorie food such as vegetables), but also drinks such as tea or coffee with milk. The best thing to consume whilst fasting is filtered water and herbal teas. Many people ask whether black coffee breaks a fast, and some people can tolerate a small amount of black coffee during a fast and still reap the benefits. But I prefer bone broth as it supplies the body with valuable minerals and extra hydration.

Click below to read Anoushka's Personal Story:

Achieving Good Health from the Inside Out.

Anoushka Davy

Facebook: @anoushkadavynutrition

Instagram: @anoushkadavynutrition