You’ve probably heard of people fasting, but do you know why or how it benefits your health? Here’s a quick run down so you’re in the know. 

What is Intermittent Fasting?

Our human bodies have evolved to go through period of less food, and period of feasting (e.g. a big hunt, or harvest). Today we are surrounded by high calorie food that is easy to obtain and quick to eat.

As well as a rise in sedentary lifestyles, chronic stress, and getting out of sync with our circadian rhythms, all this additional food has led to population wide increases chronic health conditions such as diabetes, heart diease and obesity. 

Intermittent fasting covers various different ways of not eating for a period of time. There is a growing body of research looking at WHEN we eat, as well as WHAT we eat for the optimum health benefits.

  • Periodic fasts – includes regimes like alternate day fasting, or a 24-28 hour fast where no food or very restricted calorie intake. The 5:2 diet, popularised by Michael Mosley, would fall into this category.
  • Restricted Feeding Window – This is where you shorten the house within which food is eating each day, say eating only between 10am and 6pm.

Benefits to your health

There are lots of studies showing that restricting our food intake can support benefits like

  • weight loss
  • improved blood lipids (profile of fats in your blood)
  • improved insulin response
  • better sleep
  • more energy. 


How to do intermittent fasting

Pick a method that suits you, most importantly.  Think about your goals and what can work with your job, your activity levels, your family circumstances, and other commitments. You may find it hard fasting during the day if you have to prepare meals for family members. 

Whilst you are fasting you can drink water, or herb tea, but no food, or milk in tea or coffee as this may affect the benefits. 

Restricted Feeding Window example – eat your evening meal after work at 6pm, finish all food by 7pm and don’t eat again until 7am. That’s a 12 hour fast which most people can manage without any problems.

Or try a 16:8 fast where you eat within 8 hours a day and fast for 16 hours.  This may be very challenging to begin with, so build up to this rather than launching into long period of time without food. 

How to start intermittent fasting

To help your body adjust to new patterns of eating you may find these steps helpful

  1.  Cut snacking – You might find it easier to aim for 3 meals a day first. If you’re hungry between meals then concentrate on increasing protein, healthy fats and fibre at mealtimes. 
  2. Start with 12 hours overnight (for most of this time you’ll be asleep)
  3. Identify different feelings that can be confused with hunger – are you actually thirsty, or bored? Do you feel you need to eat at certain points in the day for habit? 
  4. Ensure the meals you are going to eat are full of nutrients you need – e.g. protein, lots of veg, wholegrains and fruits to keep you well nourished. 


Who should avoid fasting?


  • If you’re on blood sugar controlling medication (e.g. for diabetes) please speak to your doctor in the first instance. 
  • Anyone with a history of disordered eating – restrictions and control can trigger conditions
  • Pregnant or breastfeeding women should speak to a healthcare professional before any restriction of food

If you want to know more about how to tailor this advice for your lifestyle and health conditions please get in touch for a 1:1 nutrition consultation. 


Hi I'm Anna Mapson, registered Nutritionist (mBANT, CNHC). I specialise in all things ‘digestive health’ and I help people with their IBS symptoms.

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To find more about out how I work and how I’ve helped people just like you, see my IBS Diet support page

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