Why fasting should be on your menu

Why fasting should be on your menu

by | Jul 11, 2019 | Physical Wellbeing

Back in the day…

In a world without electric light, humans were governed by the cycles of light and dark in everything we did, including finding, preparing and consuming food. We would acquire food when it was available, consume it, use that energy for immediate activity and store some (internally) for use until we found our next meal.

Until along came Thomas Edison…

And the presence of artificial light enabled human activity throughout the full 24 hours. This disrupted the natural daily cycle of feeding and fasting – resulting, ultimately (for those of us in developed and privileged countries) in excessive calorie intake. And we all know where that has led us – obesity, diabetes, cardio-vascular disease and a lot of medical advances creating pharmaceutical and interventionist responses to these problems.

Thankfully, in recent years, we’re seeing some clever thinking and research into the way things used to be, examining traditional approaches derived from thousands of years of evolution.

Fasting has never been absent from human society. It’s an important part of many cultures and religions. What is of major interest now, however, is the use of fasting to tackle weight management and the diseases that result from the over-consumption of calories.

Fasting is a hot topic!

There are a number of differing approaches to fasting that are being employed and researched, which lends some complexity to the field. I’m going to tease these out for you and offer some suggestions on how to give it a go.


Variations of fasting

  1. Intermittent fasting:
    1. The 5:2 diet: most people have heard of this one now. It was covered by Dr Mosley in the TV show ‘Eat, Fast, Live Longer’ and he has followed this up with numerous books that share the science and the practicalities of adopting this diet. Essentially, you eat normally for five days per week and for the other two, you restrict yourself to just 500 calories if you are a woman, or 600 calories if you are a man. It doesn’t matter what you eat to consume these calories, but of course the advice is to have lots of vegetables, some protein, low sugar and few starchy carbs.
    2. The ‘new’ 5:2 diet: this is a development on the original whereby you follow a Mediterranean diet all the time but restrict yourself to 800 calories on two days per week.
    3. Alternate day fasting (ADF): this is a continuous sequence of a fast day (consuming 0-500 calories depending on the protocol you are following) and then a ‘feeding day’ when you can eat whatever you want.
  2. Time-restricted feeding (TRF): this has been gaining popularity in recent years as perhaps an easier way of reducing the calories you consume every 24 hours. The basic premise is to only eat within a set period of time – anything from an 8 to 12-hour window being typical. In practice this means you finish eating after dinner at, say, 8pm – and you don’t eat again until 8am the next day (12-hour window) or 12pm the next day (8-hour window).

In the latter case, you are having a 16 hour fast in every 24-hour period (and are asleep for half of it). You don’t have to control your calorie intake during your feed-times (but common sense would suggest that if you go face-down in Pavlova for 8 hours, you are unlikely to see much benefit ☺️)

  1. Prolonged fasting / the Fast 800: this is another Dr Mosley recommendation for people who have a lot of weight to lose and/or want to lose weight rapidly, which as I reported in my recent blog, is no bad thing. As it sounds, you consume no more than 800 calories per day for anything from 2 to 12 weeks, whilst staying really well hydrated.


What are the gains?

There is now a growing body of research on the benefits of all types of fasting, and increasingly this research covers human subjects – not just mice!

I’ll give just a quick overview and leave you to dig around in the detail if you wish to.

(NB: These benefits are a collation of results from a range of studies – no one fasting regime will deliver all of the below results.)

  • Reduced calorie intake (D’uh!)
  • Weight loss (that can then be maintained on a less restrictive fasting regime)
  • Stimulation of the function of the mitochondria (that release the energy from food)
  • Uses up glycogen (glucose stored in your muscles and liver) and fat stores
  • Improved liver function – your body has time to digest and eliminate toxins
  • Prevention or reversal of diabetes (increased insulin sensitivity)
  • Increased daytime alertness and better mood
  • Improved sleep
  • Reduced blood pressure
  • Reduced markers of inflammation
  • Lowered risk of breast cancer
  • Reduction of asthma related symptoms
  • Delayed onset of dementia

What’s not to like about all that!

Even if you are lucky enough to be an ideal body weight, the health benefits listed above should make fasting worth considering as a long-term habit.

I would add from personal experience (and my psychologist’s brain) that there are also significant mental health benefits to fasting. When you give it a go, can stick to it and start to see some weight loss benefits, this gives you a tremendous sense of self-efficacy – “Look, I can do it!”.


Putting it into practice

If I’ve engaged your interest and you feel like giving fasting a try, then I have some suggestions for how you approach this, based on the experts and my own experiences (I have done the 5:2 diet for several years, but lost the habit a few months back… writing this blog will be setting me back on course!).

  • Consult with your GP before you embark on fasting to make sure that this is going to be safe for you. Bear in mind that some health professionals may be un-enthused (and un-informed) about these approaches to weight and health management so go prepared with the reasons you want to trial it. Also, review the advice on Dr Mosley’s website about who shouldn’t try a fasting diet.
  • If you have a lot of weight to lose and want to see rapid results (maybe because you are pre-diabetic) then the Fast 800 might be the way to go, but this could be hard to adapt to straight away.
  • A gentler introduction to fasting would be to first introduce the Mediterranean diet as much as possible (look it up, I’m not repeating it here). This sets you up with some positive eating habits before you start to restrict either your calories consumed or the time you will eat. You can go straight to fasting without adopting the ‘Med diet’, but it’s definitely worth moving your diet in this direction.
  • Next, try time-restricted feeding – decide not to eat past a certain time in the evening and not to eat again ‘til a certain time in the morning. This will cut out all late-night snacks and delay your calorie intake the next day. Start with a 12-hour fast (8pm to 8am) and then build up to 16 hours.
  • Try and make this work in your schedule, e.g. no early breakfast meetings, avoid late dinners if you can. When you are at home, brush your teeth straight after dinner to help keep away from snacks. Keep busy in the morning and avoid milky coffees – these are crammed with calories. Ideally have only black tea or coffee until you ‘break your fast’. And don’t stress about missing breakfast – as we learnt in my last blog, it doesn’t matter (it’s only Mr Kellogg who thought it did).
  • If the TRF works well for you, yet you want to lose weight faster, then add in the 5:2 regime. Pick two days per week when you can avoid any eating out. Plan your food intake to still fall within your ‘feeding time’ but reduce the calories. Split the days (Monday and Thursday work well). Plan ahead for meals you can have (there are some 5:2 recipe books around). Check out Dr M’s website for guidance and recipes.
  • Keep hydrated – lots of water, herbal teas and sparkling water can make you feel fuller.
  • Weigh yourself once per week, first thing in the morning after a fast day!
  • Persevere – adjusting to 500-600 calories per day is hard. But you can do it. Your body doesn’t need the excess – you can feel hungry and it’s not the end of the world. And you can look forward to eating normally the next day ☺️
  • An added bonus from the 5:2 is that if you tend towards too much alcohol, you can’t make room for this in your calorie count – so you automatically have two alcohol free days per week without trying. And you know what? You don’t even notice, because you are thinking more about food!
  • Get other people fasting with you – at home or at work. They can keep you company and help motivate you.
  • Remember that weight loss will happen faster if you are burning more calories, so keep up and/or add in more exercise and movement to your day.
  • Accept that you will have setbacks – we all do whenever we try to establish new habits. Just move on to the next fast day and begin again.


Good luck!



  • Dr Michael Mosley’s website: https://thefast800.com/the-science/
  • Longo,V.D. and Panda, S. (2016) Fasting, Circadian Rhythms and Time Restricted Feeding in Healthy Lifespan. Cell Metabolism, Vol 23:6 pp 1048 – 1059
  • Gabel, K, et al (2018). Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutrition & Healthy Ageing 4(4): 345–353.



See the GLWS in action now with a suite of sample reports

If you are a leader, or a coach working with leaders, you can find out how the GLWS works in practice by reviewing our suite of reports. Sign up here to get instant access.