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Can You Combine Intermittent Fasting and the Keto Diet?

7 mins read
Mariia Roza
Written by Mariia Roza on November 01, 2021
Ievgeniia Dobrynina
Fact checked by Ievgeniia Dobrynina
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Dr. Olena Avdiievska, MD, RDN
Medically reviewed by Dr. Olena Avdiievska, MD, RDN
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Intermittent fasting and the ketogenic diet have been the buzzwords of the past few years. Given their popularity, some health and weight loss writers are trying to promote their combination for even faster results and greater health benefits. Let's find out if this is the case!

Among the biggest advocates for the new approach are celebrity health and fitness coach Thomas DeLauer and Dr. Jason Fung, Nephrologist and diet expert from the University of Toronto. They state that by adding intermittent fasting protocols to your low-carb diet, you can get into ketosis easier and lose fat faster.

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Why does this happen? Should you combine two diets to get better results? Is following the keto diet and intermittent fasting protocols together safe for everyone? Let’s find out!

Intermittent fasting and the keto diet in simple words

Intermittent fasting is a dieting protocol when you have prolonged periods of fasting and shorter periods of eating. The most popular are 5:2 fasting when you eat 5 days a week and fast for 2 days; 16:8 when you eat for eight hours and fast for 16 hours; and 23:1 or the OMAD, when you eat only one meal a day within a one-hour window. This approach became extremely popular when Yoshinori Ohsumi has won the Nobel prize in Physiology or Medicine for his studies of autophagy. 

Even though intermittent fasting looks like a new magic pill, multiple studies and reviews state that more research on its efficacy and potential harms should be conducted. Even papers on autophagy show no significant difference between the calorie restriction and intermittent fasting on autophagy promotion. 

However, there are also many papers showing the potential benefits of IF not only for weight loss but also for health. For example, some studies show improved neuroplasticity and brain health among people who follow intermittent fasting protocols. What’s more, for some individuals, intermittent fasting is easier to follow than a calorie-restrictive diet and hence, this approach facilitates fat loss and provides all the benefits of lower BMI for health.

Summing up: There is not much evidence that intermittent fasting is somehow more effective than common low-calorie diets for weight loss, however, this approach might be easier to follow for some individuals.

The ketogenic diet was developed almost a century ago as a way to treat epilepsy among children, and today it has gained popularity due to its weight-loss efficiency. The main point of the keto diet is to get into ketosis. Ketosis is the state when your body shifts from using glycogen as its primary source of energy to ketone bodies. This metabolic change happens when you stop consuming carbohydrates, both during the ketogenic diet or the prolonged fasting period.

According to research, the ketogenic diet might have a plethora of health benefits.

  • It can improve some cardiovascular risk factors, like obesity, type 2 diabetes, and HDL cholesterol levels. However, researchers state that due to the high consumption of fats some negative effects are also possible.
  • The ketogenic diet has the potential to help treat some types of cancer, though more randomized controlled clinical studies are necessary to provide specific recommendations.
  • A low-carb diet has a greeted impact on glycemic control among patients with type 2 diabetes compared with diets high in carbohydrates.
  • Low-glycemic index diets, as well as the ketogenic diet, are efficient tools to treat epilepsy in patients of all ages.
  • There’s only a pilot study on the benefits the keto diet might have on polycystic ovary syndrome, which means more studies should be conducted. However, low-carb diets might become a promising treatment strategy for this health condition.

Summing up: The keto diet drastically restricts the consumption of carbohydrates. It boosts weight loss and has a bunch of other health effects.

Benefits of dieting two diets: How does combining IF and keto supposed to work?

The common recommendation on combining IF with the keto diet is to start with the low-carb diet and add intermittent fasting protocols to your dieting in several weeks when your body is used to using ketone bodies as its primary source of energy. According to the IF plus keto advocates, shortening your eating windows and prolonging your fast periods should be easier when you’re already in a state of ketosis.

How should combining the two diets stimulate your weight loss? Thanks to the decrease of calories you consume. Now, you don’t only cut off an entire macronutrient from your diet (due to keto), but also skip breakfasts or dinners, depending on what IF protocol you’ve chosen. Even though the ketogenic diet advocates state that this dietary approach is not about counting calories, decreasing your calorie intake helps with weight loss.

What are the disadvantages of combining IF with keto?

The main weak point of combining intermittent fasting with the keto diet is that it is extremely restrictive. 

When we talk about healthy weight loss that you would maintain for the rest of your life, we always tell you that your diet should be sustainable. You should opt for a lifetime change in your eating habits and not a short-term crash diet.

Who should not combine IF with keto?

The keto diet is quite popular among patients with prediabetes or type 2 diabetes as it might lead to improvement in glycemic control and even medication reduction. However, the intermittent fasting protocols might lead to a higher risk of hypoglycemia among patients with type 2 diabetes.

Of course, people who are not a good fit for the keto diet or intermittent fasting shouldn’t try to combine them. People with previous or current eating disorders should not try intermittent fasting. Pregnant or breastfeeding women are also bad candidates for intermittent fasting. People with kidney disease or other health conditions should consult their health providers before they start following the keto diet or intermittent fasting protocols.

Is it right to combine these two diets?

If you decide to follow something as restrictive as intermittent fasting plus keto combo, answer yourself a question: What are you going to do after you lose weight? Will you skip dinners and refrain from carbs for the rest of your life? Are you going to come back to your previous eating habits? Will you change your diet in some other way?

Combining intermittent fasting with the keto diet is a severely restrictive way to lose weight. What’s more, there is no reliable scientific evidence that this approach is more efficient than other dieting methods.

Summing up

It seems like the era of crazy fad diets, like eating only baby food or only products of one color is over, but if there is a gap, something will fill it. Today, these are nutrition approaches backed up by some research. The combination of intermittent fasting and the ketogenic diet seems to fit in the need of people for some quick fixes with a scientific background.

However, even though there is some research on the ketogenic diet and intermittent fasting, there is not enough research on combining both diets. What’s more, there is no strong scientific evidence proving that this approach is more efficient or beneficial than a common low-calorie diet.

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