Intermittent Fasting and the Keto Diet

The keto diet and intermittent fasting are two of the most popular health trends at the moment. Many health-conscious people follow these methods to drop weight or to control certain health issues. Intermittent fasting is also popular in bodybuilding circles, as a means to improve bodily composition.

Both keto and intermittent fasting make use of the body’s ability to enter ketosis. 


The keto diet and intermittent fasting are two of the most popular health trends at the moment. Many health-conscious people follow these methods to drop weight or to control certain health issues. Intermittent fasting is also popular in bodybuilding circles, as a means to improve bodily composition.

Both keto and intermittent fasting make use of the body’s ability to enter ketosis. 

However, since both diets are based on ketosis, it begs the question, is it worthwhile or even healthy to combine the two? Let’s take a look at both of these health fads, what they’re about, and also what the science says about combining them.

What is the Keto Diet?

Simply put, the ketogenic diet (or keto) involves high-fat, low-carb consumption. Ideally, the carb consumption should be reduced to 20 to 50 grams per day. This forces your body to rely on fats as its main energy source instead of glucose [1]. During ketosis, your body will break down fats to form ketones, which serve as an alternative fuel source [2].

The calorie breakdown of a ketogenic diet typically involves 70-80% of calories from fat, 15-30% calories from protein, and 0-10% calories from carbohydrates. 

Although the keto diet, just like intermittent fasting, is mainly used for weight loss, it also has a lot of extra health benefits. The keto diet has been used for nearly a century to treat epilepsy and shows a lot of potential for treating other neurological disorders [3], such as improved mental symptoms in patients with Alzheimer’s disease [4].

What’s more, studies suggest that it may improve blood sugar, improve insulin resistance, and lower heart disease risk factors [5, 6].

What is Keto Cycling?

Because the keto diet is sometimes accompanied by “keto flu”, many find this diet hard to stick to. Enter keto cycling as a way to mitigate this.

Keto cycling, also referred to as cyclical keto diet, involves following a ketogenic diet for a few consecutive days, then having a day (or more) off and repeating. This is similar but not the same thing as carb cycling.

Carb cycling is more about high protein, moderate fat intake, so you are not really in ketosis in the same way that you would be on keto cycling, where you’d eat moderate protein and high fat. Also during keto cycling, your carb intake is lower than it would be on carb cycling.

The Health Benefits of the Keto Diet

With its growing popularity, keto has received a lot of attention from researchers. In human observation and studies, scientists found that the keto diet has a bunch of health benefits. It has shown improved cholesterol levels [7], improved insulin sensitivity [8, 9], and in some cases, lower blood pressure [10]. 

Common benefits of the keto diet include significant weight loss in initial stages [11], making meals more satiating, reducing cravings for processed and high-carb foods. Ketosis also suppresses appetite [12], regulates inflammation, and increases immune function. 

The keto diet has also helped to reduce symptoms of various medical conditions, such as reducing the severity of type 2 diabetes [13], reduction in blood triglycerides [14], treating numerous types of cancer [15]. It is also effective against metabolic syndrome, which is a collection of symptoms that include, abdominal obesity, elevated blood pressure, elevated fasting blood sugar levels, high triglycerides, low “good” HDL cholesterol levels [16,17]. 

In addition some studies suggest it reduces and slows the progression of neurological disorders like epilepsy, Alzheimer’s, and Parkinson’s disease [18-19], as well as polycystic ovary syndrome (PCOS), a hormonal disorder [20].

The Negative Effects of the Keto Diet

Apart from the aforementioned ‘keto flu’, researchers still do not know much about the long-term effects of the ketogenic diet (beyond the first 2 years) [22].

One possible risk of any restrictive diet includes vitamin and mineral deficiencies. Other potential risks of a high fat, high protein diet include an increased likelihood of developing kidney stones, fatty liver, hypoproteinemia, or low levels of protein in the blood.

Also, because your fiber intake in the keto diet is so low, another common symptom that individuals who follow a keto lifestyle have reported is being constipated.

The high-fat nature of the diet could also have negative impacts on heart health. This is due to the high levels of low-density lipoprotein cholesterol. Some people also experience dehydration because they’re eradicating glycogen, which holds water, from their bloodstream.

Could Combining Keto and Intermittent Fasting Help You Lose Weight?

The keto diet and intermittent fasting are both reported to promote weight loss as one of their benefits. 

Pairing intermittent fasting with the keto diet may make these weight loss benefits much more pronounced, since fasting can help you reach ketosis quicker. Once ketosis is reached via fasting, the state can be maintained by adhering to a keto diet.  As every person is different in terms of how long it takes their body to reach ketosis, adding the keto diet to intermittent fasting can help ensure your body has the maximum opportunity to reach this state.

Intermittent fasting can be paired with any diet relatively easily. The diet of choice decides which food may be eaten, while the introduction of intermittent fasting simply dictates the window in which you are allowed to eat.

The Health Benefits of Combining Intermittent Fasting and Keto

Intermittent fasting and the keto diet have a host of reported health benefits when practiced in isolation, but some of these benefits are heightened when combining the two.

The main advantage of pairing these two methods is that ketosis is reached faster, and may be more pronounced.  This leads to increased weight loss, reduced hunger, sustained energy, and increased cellular renewal, as reported in numerous studies.

It has been suggested that adding intermittent fasting to the keto diet may cause the transition into ketosis to be made much quicker and smoother, limiting the effects of keto flu.

According to studies, the keto diet may also aid in health benefits brought on by intermittent fasting. One of these add-on benefits is that a keto diet provides protection and a healthy fuel source for stem cells, which are produced in larger quantities when fasting.

In much the same way, it is reported that fasting and the keto diet combine to combat cancer-cells by drastically reducing sugar levels in the body, which cancer cells use as fuel.

Are There Any Health Risks?

Both Keto and Intermittent Fasting do have their fair share of pros and cons. So, following two diets at once could mean that you end up with the worst of both worlds as you have a risk of double the side-effects. This is especially something to consider if you are a beginner in either “diets”.

Experiencing low blood sugar, nausea, mood swings, fatigue, and constipation are all common symptoms that have been reported in the starting days. This is dubbed the “keto flu”. This is due to the detoxifying effect that both these diets have on your body.

Also, do remember that trying the two diets together also requires a lot more patience and commitment, since it’s a very strict way of eating.

However, if you do decide to try the diets, the best would be to ease into them, rather than going all-in. Add foods in your diet that release energy slowly, and don’t completely cut out carbs. If you have a history of eating disorders, this method is not advised by medical professionals.

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