Intermittent Fasting on a Keto Diet

The keto diet alone has proven to be a life-changer—even lifesaver—for a growing number of people.

But as we learn more and more about how ketosis works, scientists and “diet-hackers” have found another valuable method of eating (or rather, not eating) that may expand the keto diet’s benefits even further.

They’ve found that it’s not just about what and how much you eat, but when you eat. When all of these components are aligned, there’s no stopping you.

This is the claim of intermittent fasting on a keto diet—a combination that can bring about some incredible benefits, from weight loss to mental clarity to extending your life. 

Intermittent Fasting on a Keto Diet

While intermittent fasting isn’t a requirement on a keto diet, it can certainly give you a nice boost—in ketones, energy, and overall results.

If you have yet to start a keto diet, or have found yourself stuck in a plateau, you may want to consider trying intermittent fasting.

Intermittent fasting itself promotes the production of ketones, which can help you reach ketosis faster and with greater ease. Fasting also triggers a cell renewal process called autophagy, making your body run more efficiently.

For keto beginners, intermittent fasting can also reduce some of the unwanted symptoms that come with the keto flu, making your transition into a keto lifestyle much smoother.

How Long Can We Last Without Food?

Have you long thought that fasting is merely just a form of self-torture? You are not alone!

Thing is, we often don’t give our bodies enough credit. They are designed to survive—and ultimately thrive—as long as we know how to support some of its most complex processes.

We’re set up to live without food for far longer than you may think. 

When you first start fasting it may seem an impossible task, and, believe us, you’ll start daydreaming about food like you never have before. 

This is okay, and it’s totally normal. It’s just your mind freaking out a bit, but just know that your body is far from starving, and you’ll soon get over this mental hurdle.

Heck, Mahatma Gandhi lasted 21 days without food, and Terence MacSwiney, an Irish political prisoner, went a whole 74 days foodless before dying in 1920.

Of course, these are extreme cases, and nothing you’ll ever have to endure, but it’s a good reminder of how strong and resilient our bodies are.  

Even if you fasted for three full days (something we’ll discuss later), you will likely not experience any health complications.

This is a good thing to remember when you first start intermittent fasting. Soon enough, you’ll find that a 15- or 16-hour daily fast will feel perfectly normal.

Eating Windows

Structuring your days around specific eating windows is one of the more preferable ways of intermittent fasting.

You can schedule your eating window to whatever works best for you and your lifestyle. For example, you may choose to fast for 16 hours, while giving yourself an 8-hour eating window. This could mean skipping breakfast and then allowing yourself to eat from, say, 1pm-9pm.

As your body adapts to intermittent fasting, you can start to experiment with shorter eating windows—but only if you want. Just remember to always listen to your body and adjust your eating and fasting windows to whatever makes you feel your very best.

How Does Intermittent Fasting Work?

The main and most immediate benefit of intermittent fasting is that it can simply help you cut calories—without you even realizing it.

Your body can only handle so much food in so much time, so if you restrict that time, you’ll inevitably eat less.

Ketosis and fasting actually have a whole lot in common. When you’re in ketosis, your body is already acting like it’s in a fasted state by breaking down stored fat to use as energy.

Over time, intermittent fasting can promote weight loss, boost your metabolism, lower the risk of chronic diseases, and maybe even reverse aging.

What About Muscle Loss?

A lot of people fear losing muscle while fasting, but the science just doesn’t prove this. Intermittent fasting can improve muscle synthesis when you exercise in a fasted state (1).

Some researchers also believe that intermittent fasting may be more effective in maintaining muscle mass than traditional non-fasting diets (2).

The reason you can avoid muscle loss during intermittent fasting comes back to the crucial process of autophagy, which helps renew and repair cells—including muscle cells—letting them thrive instead of die.

What About Refeeding Syndrome?

Refeeding syndrome can occur if you fast or are malnourished for more than 5 days.

If you’ve fasted for this long and then you resume eating, you could experience major, possibly even fatal, shifts in fluid and electrolyte balance. Add a keto diet to that mix, and it could turn ugly.

One of the top 3 keto mistakes is not taking into account the greater loss of water and minerals that come with a low-carb diet.

The best thing to do after a fast is to fill your plate with mineral-rich sources, including foods like leafy greens, salmon, and avocado. Feel free to liberally add unrefined pink or sea salts, too. Electrolyte supplements can also be helpful.

That said, intermittent fasting should never involve abstaining from food for such a long period of time, so you shouldn’t experience any complications, especially those related to refeeding syndrome.

Tim Ferriss’s 3-Day Ketosis Boost

Keto researchers and advocates like author Tim Ferriss have found that, alongside daily intermittent fasts, doing a longer fast every now and then could offer some amazing benefits.

Ferriss suggests a 3-day fast, 3 times a year (though he personally does this once a month).

If you’re just starting out on the keto diet or feel you need an extra push, this type of fast can help get you into ketosis quickly and efficiently.

Ferriss chooses to do this fast from Thursday night to Sunday night. Throughout these 3 days, it’s essential you get plenty of sleep—it will certainly help with any fatigue that may seep in.

Here are the details of his plan:

Thursday Evening:

  • Enjoy a keto-approved dinner around 6pm. This will be your last meal before your fast begins.

Friday Morning:

  • Upon waking, consume exogenous ketones (try Konscious Keto’s Keto Activate to get you started).
  • Within 30 minutes of waking, get ready for a nice, long walk (a 3-4-hour one, to be exact). Walking will use up your glycogen stores to get you into ketosis faster.
  • Stay hydrated on the walk (bring at least 1 liter of water) and be sure to add a little salt to make sure you’re getting enough electrolytes.
  • If you don’t have time for such a long walk, try doing a 45-60-minute HIIT (high interval intensity training) session instead.

Friday Day:

  • Upon waking, consume exogenous ketones (try Konscious Keto’s Keto Activate to get you started).
  • Consume MCT oil 2-3 times during the day to give you an extra boost of energy as your ketone levels start to increase naturally.

Saturday Morning:

  • Upon waking, consume exogenous ketones (try Konscious Keto’s Keto Activate to get you started).
  • Next, test your ketone levels with a ketone blood meter.
  • Your goal is 0.7mmol or higher. If your ketones are under 0.7mmol, you may want to go for another long walk before retesting. 
  • You can use a urine strip if you prefer but these are not as accurate. 

Saturday & Sunday Day:

  • Upon waking, consume exogenous ketones (try Konscious Keto’s Keto Activate to get you started).
  • Consume MCT oil, coconut oil, or exogenous ketones, if and when you feel you need it.
  • Keep hydrated and continue to add salts to your water or opt for electrolyte replacement supplements.
  • You can also consume some nori sheets for minerals and a little something to chew on.

Sunday Evening:

Of course, you can pick any 3 days that this sort of schedule will work for you. The addition of exogenous ketones, MCT oil, or coconut oil can help you get through feelings of hunger and fatigue over these 72 hours.

Once you break the fast, remember to get in plenty of minerals and let yourself indulge with your favorite keto meal!


Remember that fasting has some incredible benefits, but it’s also not required on a keto diet. If it’s just not your thing, don’t force it. You’ll still experience all of the amazing benefits that come with ketosis.

After all, the keto lifestyle is not meant to make you feel miserable—quite the opposite actually.



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