Intermittent fasting, or simply the idea of skipping meals or eating within a certain window, has been around for a long time. Intermittent fasting on keto is a different ball game, as you are fuelling your body with an entirely new source – fat!
IF has been brought into recent publicity by Dr Michael Mosley through both his book, The 5:2 Fast Diet For Beginners and his website, https://thefastdiet.co.uk/
Dr Mosley is a major promoter of fasting and once you dive into the scientific evidence, you can see why.
Based on these studies and my own experience, I have learnt that there are a number of different ways of fasting and using intermittent fasting on keto effectively.
These are summarised simply below;
You eat normally for 5 days, and have 2 fast days of around 500 calories.
You fast for 16 hours a day, and then consume your daily calories in a 6 hour window (most people eat from 1pm – 7pm)
Alternate Day Fasting
On each alternate day, you eat around 500 – 600 calories and return to your normal calorie intake the following day
Fasting as you see fit, when your body feels like it. Only eating when hungry and skipping meals when it fits in with your hunger and lifestyle
This could be anywhere from 1 – 2 days to extremely long times, with some studies following people who have fasted for over a year.
Benefits of Intermittent Fasting on Keto
1. Consuming Less Calories and Understanding what Hungry Really Feels Like
Once you are keto adapted, your body is surviving off fat and ketones rather than carbohydrates. One major benefit of this is feeling hungry less often, and as a result, naturally consuming less calories.
By combining this natural state of nutritional ketosis with intermittent fasting, you become aware of when you are really hungry as opposed to eating out of habit, boredom, stress or other emotions.
Realising when your body is actually hungry is a true key to succeeding on ketosis.
2. Planning ahead saves money on food
Planning a fast day/period or fasting window each day makes you very conscious of how much money you were spending on food. When you are no longer constantly thinking about food, you stop buying it and eating it as a time filler and rather only buy what you actually need.
If you plan a few fast periods into your weekly meal plan, you’ll end up saving money.
3. Saving time
You have more time when you are eating less. When I fast from dinner to dinner, I find I am more productive during the day because I’m not stopping to eat, prepare food, do dishes and need to shop less.
4. Improved insulin sensitivity
If you have been reading a bit about the keto diet, you will know that insulin sensitivity is one of the major reasons that most people are on a carb addiction cycle. When our bodies create too much insulin (from eating too many carbs/sugar), we become almost immune to it and constantly feel hungry.
Fasting resets your insulin sensitivity, meaning you feel fuller for longer when you are eating healthy fats and you don’t crave carb laden foods like you may once have.
5. Cell Regeneration & Repair
More and more research is being done into the amazing health benefits of Intermittent Fasting, and a really key area of study is the repair and regeneration of your cells. As you know, your entire body is made up of cells and repairing these are crucial to your overall health.
From a recent study author;
We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the heatopoietic system. When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged. What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back.
Things to Consider Before Starting Intermittent Fasting On Keto
Start Easy and Take It Slow
If you are interested in trying out intermittent fasting while on keto, I would suggest starting slowly and easing yourself into it. From personal experience, I have found the 16:8 fasting pattern to be the most manageable. Most people can handle not having breakfast, and then having lunch at 1pm or 2pm and heading home to a filling dinner.
Going with the flow becomes a bit difficult – your friend wants to go out for lunch unexpectedly, you forgot there was a work luncheon on or you had dinner plans on your fast day. Choose your fast days around your lifestyle to make this work for you!
Exercising While Fasting
Exercising is generally a no go while fasting, especially if you are new to it. While a walk or slow jog is ok for most people, any sort of weights or strength exercise can be difficult, exhausting and in some cases dangerous if you are pushing yourself too hard. Listen to your body – there are many professional athletes who will train fasted, but always proceed with caution.