Updated 04 January 2016

Is intermittent fasting the easiest diet ever?

Intermittent fasting as a diet sounds like a lot of hard work and denial. Not so, says Dr Arien van der Merwe who found it the easiest way to slim down her growing waistline, caused by metabolic syndrome.

You've tried the Banting, Atkins, Paleo, Dukan and even the famed Dash diet and still the excess weight persists.

Maybe it's time you gave intermittent fasting (IF) a try.

This "diet" during which you abstain from food (yes, fast) for a number of hours, or even a whole day has received quite a bit of attention over the last year.

But what put most of us off is the BBC's Dr Michael Mosley's version – the Fast Diet or 5:2 Diet, which demands that you eat normally for five days and semi-fast (500-600 calories) for two days of a week.

Read our DietDoc's analysis of the Fast Diet

That sounds pretty punishing, so it's no wonder not many of us took up the challenge.

But maybe the easier version will work, where you fast for 16 hours each day and eat normally for the rest of the day.

Those who've tried this 16:8 method say that, after the first couple of days, it's surprisingly easy to follow as your body gets used to not wanting food early in the day.

Many dieters say that once they start eating they are tempted to eat all day long. But with IF you ignore the hunger pangs – and they go away, and when it is finally time to eat you're not that hungry and you certainly don't feel like overeating either.

Plus, a welcoming side effect of IF is the break from constant meal planning and food buying and prepping. You'll find your fridge stays fuller for longer!

Dr Arien van der Merwe, a GP specialising in body-mind and integrative natural medicine, health book author and director of the William GG Gauché's Weight Control Clinic in Pretoria says the fasting needn't be tough.

Read: Book review of Dr Arien van der Merwe's Managing Diabetes and health-related problems

In an exclusive interview with Health24 she explains how and why intermittent fasting worked for her:

"After I realised that I had symptoms of metabolic syndrome despite my healthy lifestyle, I started experimenting with even more options to manage it effectively.

"One of the techniques that really works for me is Intermittent Fasting or IF, especially to lose the excess fat around my waist."

How the easy version of IF works

Intermittent Fasting 16:8 means you limit your eating in any 24-hour cycle to 8 hours and during the remaining 16 hours you don't eat at all.  

This might sound horrible – 16 hours spent like a hunger striker is a little scary. And the prospect of doing that most days of the week can cause sheer terror! That is until you realise that we sleep 8 hours in every 24 hour cycle.

Dr Arien explains that it takes about six to eight hours for your body to burn the carbohydrates stored as glycogen.  

After that – and here comes the good news – your body starts burning fat as its primary source of fuel.  

This means that if you eat your last meal at around 7 o'clock (or 6 o’clock) in the evening, have a good night's rest for about 8 hours and then only eat a postponed breakfast at 11 (or 10) the next morning, you are turning your natural metabolic processes into a "fat burning machine".

Are there other benefits to IF?

Dr Arien says that not only does IF help your body burn fat, it also gives it a much needed break to recover, re-balance and restore, and is great to ensure a long and healthy life.

The break from food helps to avoid the accumulation of free-radicals in the cells associated with disease and ageing.  

With regards to metabolic syndrome, it lowers blood sugar and allows the body to preferentially start burning fat as source for fuel. It improves insulin sensitivity of cell receptors because it prevents insulin and glucose spikes after high carbohydrate meals eaten too often.

IF can prevent type 2 diabetes and even reverse it entirely, she says. "I know I did and I can vouch for the results. For me, it has been the single biggest behaviour adaptation, finally shifting the fat that has been stuck for so long.  I find it an easy to maintain, healthy habit."

Satchidananda Panda, an associate professor of regulatory biology at the Salk Institute for Biological Studies in San Diego, California, has said that fasting alone is more powerful in preventing and reversing some diseases than drugs.

He regards eating three meals a day, plus snacks, abnormal from the perspective of human evolution. He believes that by simply limiting food intake to 8 hours gives you all the benefits – without having to worry about food intake.

Some of the other added benefits is an increase in growth hormone, better sleeping patterns, less inflammation in the body and protection from heart disease and cancer.

One of the simpler reasons why IF helps you lose weight is because you're taking in fewer calories each week.

Dr Luigi Fontana, a research professor of medicine at Washington University School of Medicine in St. Louis, says that if you can stick with it, IF can help you successfully cut calories and lose weight because, during the course of a week, you cut about 20 to 25 percent of your overall calorie intake.

Q&A about IF

When you do eat, do you limit fats/carbs or any other foods, or do you eat as you’d normally do?

During the 8 hour eating period, one can eat normal portions of low GI / low GL carbs, with high quality proteins (esp. fish), 2-3 portions of fruit, 5 portions of veggies etc. – a normal healthy diet, keeping portion size in mind if you want to lose fat.

"I find that eating breakfast around 10h00-11h00, then eating lunch only around 3-4pm often means I don’t feel hungry at all later – thereby restricting calorie intake quite naturally."

Any tips to stave off the hunger or if you’re feeling peckish between the 6/7 pm meal and before you go to bed?

You won’t feel peckish if you include sufficient protein in your evening meal.

You could have a cup of rooibos tea with a little milk and stevia/xylitol sweetener if you must.

My favourite is a sleep drink made with a pinch each of cinnamon (or a cinnamon stick), ginger and turmeric in a glass with hot water or milk mixed with water (50:50) and some xylitol/stevia for sweetness. This is an excellent anti-inflammatory mixture, as well as natural sleep aid.

Feeling peckish is simply a habit that can easily be "unlearnt" with a little practice.

In the morning, a cup of good quality coffee, with some milk, can be used to stave off hunger pangs.

However, most people with insulin resistance or full blown metabolic syndrome and diabetes actually don’t feel all that hungry in the morning as their fasting blood sugar is actually still quite high.

For how long or often should one do IF? Should it become part of your lifestyle?

It can become part of your healthy lifestyle if you do it most days of the week (I try to do it 5 days a week), without becoming obsessive. If I have to go out, I try to eat a healthy meal at home to fill me up.

Would you gain again if you stopped doing IF?

It shouldn’t happen if you’re careful about what you eat. Go back onto IF as soon as you notice you're picking up weight again.

Tips for making IF work harder

  • Start the day with tea or coffee and eight minutes of exercise to 'jump-start the metabolism'.
  • Eat home-cooked, balanced meals that include protein, fruits, vegetables, whole grains and healthy fats at every meal.
  • You can enjoy dessert and a glass or two of wine, but try to keep these in the 8-hour eating window.
  • Some fasters extend the 16 hours by a couple of hours now and again, up to 24 hours once a week. Do this on a day when you're busy to keep your mind off food.
  • Try the diet for at least 3 weeks, but preferably 5 weeks, to see if it works for you.
  • If you're struggling at first, eat breakfast earlier and delay it by an hour as you go on.
  • Make the first meal of the day nutritionally dense to avoid overeating later in the day.

Final word

IF can be greatly rewarding if you follow the rules. If you are going to overeat or binge in the 8 hour eating window, you will not lose weight nor experience the other health benefits.

Dr Mosley and other scientists maintain you won't slow down your metabolism by fasting – for that to happen you have to fast for at least 3 days at a time. In fact, studies show that short-term fasts actually boost metabolism.

Research also shows that you won't lose as much muscle mass on this diet as people generally do on a calorie-restricted diet.

Finally, IF may not work for everyone and is not recommended for children. If you have an underlying illness, discuss IF as an option with a dietitian or your GP before going it alone.

Health 24 has teamed up with SleekGeek to bring you this short challenge that will give you one healthy habit to complete each day for 30 days, helping you become the Ultimate You.


Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? - Obesity reviews © 2011 International Association for the Study of Obesity
The Effects of Intermittent Energy Restriction on Indices of Cardiometabolic Health - Research in Endocrinology
Fasting cycles retard growth of tumors and sensitize a range of cancer cell types to chemotherapy
Sci Transl Med. 2012
Alternate-day fasting in non-obese subjects: effects on body weight, body composition, and energy metabolism, American Journal of Clinical Nutrition


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