The ketogenic diet and intermittent fasting are two of the biggest health trends right now, with over one million searches being made for the keto diet every month on Google. Numerous scientific studies have found that the two methods indeed play a crucial role in weight loss and managing other health conditions. This explains why these two practices have become even more popular amongst health-conscious people looking for effective and safe alternative ways of losing weight.
The health benefits of the two methods have substantial scientific backing, but there is the question of whether one can safely and effectively combine the keto and intermittent fasting benefits. In this article we will discuss the details of keto and fasting. But before diving into that, you need to first understand what intermittent fasting is.
What Exactly is Intermittent Fasting?
Intermittent fasting, also simply referred to as IF, is a type of dieting approach where you limit your food consumption to a specific window of time. While the keto diet involves significantly cutting down carb intake (preferably to less than 50 grams per day) and increasing fat intake, IF involves fasting for a set period of time and then eating during a specific window of time.
Types of Intermittent Fasting
1. The 5:2 Diet
This type of intermittent fasting involves eating a normal healthy diet for 5 days of the week while limiting your calorie intake to 500 for 2 days of the week. While there is no particular order that you should follow, you need to ensure that there is a non-fasting day between the 2 chosen days.
On these fasting days, men can eat up to 600 calories, while women should limit their intake to 500. This means eating 2 smalls of 250 calories each.
On your fasting days consider going for high fiber and high protein meals, as they will help to fill you up.
2. Eat Stop Eat Method
This method is also referred to as the 24-hour fast. It was developed by author Brad Pilon, and it involves fully fasting for 24 hours straight and then resuming your normal healthy diet. It is often done once or twice a week.
In this type of diet, you can choose to go from breakfast to breakfast or lunch to lunch without eating.
24-hour Fast Benefits
With the eat stop eat method, you will still gain the overall benefits of intermittent fasting including the following:
- Weight loss
- Reduced insulin and blood sugar levels
- Increased burning of fat
- Reduced risk of type 2 diabetes
- Improved heart health
- Reduced cancer risk
- Many more...
However, there are some unique features of the eat stop eat method that make it more appealing than other methods of IF.
Top Advantages of the East Stop Eat Method
- Flexibility: One of the key benefits of the 24-hour fast method is that it is flexible. Depending on the nature of your schedule, you can fast once or twice a week. Secondly, you also get to choose when the 24-hour fast begins and ends to fit your lifestyle.
For instance, if you have a busy work schedule and need your morning boost, then you can take your breakfast then fast till the next breakfast. Or, if you are committed to family or late-night dinners, then you can choose to go the dinner to dinner route.
- Sustainability: Many people are usually unable to commit to their IF plans as they are simply unable to deal with constant hunger. However, the 24-hour fast plan allows you to eat whatever you want for 5 or 6 days - provided that it is healthy- hence, you don't have to starve yourself each day. Also, you are allowed to take one meal on your fasting days but reduce your calorie intake to below 25% of your normal intake.
3. Alternate-Day Fasting
Alternate day fasting means fasting every other day. People who undertake this method of IF normally alternate 36 hours of fasting with 12 hours of eating. Considering that fully fasting can be quite extreme, especially for beginners, there are some variations to this approach. For example, on your fasting days, you can eat but limit your calorie intake to just 25% of your normal intake or 500.
Strict ADF is often considered the most extreme dieting approach. However, it has been found to provide numerous health benefits.
Benefits of 36-hour Fast
The overall long-term benefit of the alternate-day fasting method is a longer healthier life. This is attributed to other benefits of ADF such as:
- Weight loss and reduced belly fat
- Increased ketone levels in the body which helps to promote health
- Reduced cholesterol levels
- It helps to reduce the levels of a biomarker that is linked to inflammation and age-associated conditions
4. Time-Restricted Intermittent Fasting
As the name suggests, these types of intermittent fasting methods involve limiting your food consumption to certain times of the day. Here, you have specified eating and fasting windows. There are two main ways of going about this:
i) The 16/8 method:
Here, you fast for 16 hours and limit your eating to 8 hours. This means eating only between 11 a.m. and 7 p.m. or 12 p.m. and 8 p.m.
The 16/8 method is also referred to as the Leangains protocol. Fitness expert Martin Bekhan was responsible for popularizing this method.
To put it more simply, the Leangains protocol is essentially abstaining from eating anything after dinner and then skipping breakfast. So, if you finish eating your supper at 8 p.m. then take your next meal at noon the following day, then you will have basically fasted for 16 hours.
A study conducted on 34 participants found that those who practiced the 16/8 method lost 14% more fat than those following a normal routine.
ii) The 14/10 method:
In this method, you fast for 14 hours and limit your eating to 10 hours. This means eating only between 10 a.m. and 8 p.m.
It is worth noting that the hours spent asleep are also counted as fasting hours. This helps make it more sustainable and favorable to a lot of people. Considering the fact that women tend to cope better with shorter fast periods, therefore they are advised to follow the 14/10 method.
iii.) Important thing to remember on both plans:
Again, to realize success with either the 16/8 method or the 14/10 method, you need to stick to a healthy diet. Junk food and foods with high-calorie content can severely affect the effectiveness of this IF technique.
Can People Over 40 Years of Age Benefit From Intermittent Fasting?

The simple answer is yes. However, it is highly recommended that before undertaking any form of intermittent fasting, you need to consult your doctor. Any adult above the age of 40 years can undertake and benefit from IF as long as they are in good health and have no serious health conditions.
Fasting and severely limiting calorie intake can cause severe complications for people suffering from conditions such as diabetes. In addition, skipping meals is detrimental to people who are under blood pressure or heart disease medications.
Intermittent Fasting for Women Over 40
Intermittent fasting is particularly beneficial to women over 40 years old who are often advised against dieting and exercising at the same time. As a woman, there are numerous hormonal changes, lifestyle changes, and exercise issues that you have to deal with when you hit your forties.
According to a study conducted by researchers at the University of North Carolina found that by reducing your calorie intake by 30% (1400 calories per day for women) and exercising at the same time can lead to bone density loss. This is even made worse by the effects of menopause. Low-calorie dieting combined with exercising for women over 40 has also been found to have adverse effects on the skin.
Thus, intermittent fasting offers women over forty a better solution when it comes to weight loss and improving health. This is due to the fact that IF is effective in burning fat even in people over the age of 40. Keto and intermittent fasting benefits can significantly help to boost the health and well being of women over 40.
Does Intermittent Fasting Enhance Your Immune System?
You might be wondering whether IF has any effect on your immunity. Well, you will be pleased to learn that, yes, intermittent fasting has a positive effect on your immune system. For a long time, doctors were baffled by a rather strange occurrence where patients suffering from certain conditions showed signs of improvements after going without food for a day or two.
However, three studies on mice and humans were published in the Cell journey in 2019 trying to explain how fasting temporarily affects the immune system. The studies were carried out on different immune cell types and how the body responded to protect these cells during fasting.
Each study investigated a different type of cell and how each reacted to fasting.
One of the studies focused on monocytes, which are white blood cells that directly attack pathogens. These type of cells are normally responsible for inflammatory responses. During the study, it was discovered that these cells reduced in the bloodstream as both humans and mice fasted.
On further investigation, it was found that while the bone marrow was still producing monocytes, very few of them were being released into the system. As a result, the researchers noted that there were reduced inflammation levels in mice that had multiple sclerosis-like symptoms. The reduced inflammation levels helped the mice to become healthier.
The two other studies were conducted on T cells and B cells. These are the cells that are usually responsible for providing immunity against previous infections. They are also responsible for identifying and destroying pathogens.
During fasting, these cells retreated back to the bone marrow to survive. In one of the studies, it was found that memory T cells - cells that release molecular chemicals that destroy cancers and pathogens - not only survived, but they were also revitalized. This means that they were able to offer the body better and more improved protection.
As you can see, intermittent fasting will not only help you in losing weight, but it will also help in optimizing your immune system.
Benefits of Intermittent Fasting
- It reduces the risks of neurodegenerative diseases.
- It increases body metabolism for fat burning.
- Reduces insulin levels and increases hormone for human growth.
- Minimizes risks of heart disease.
- Helps in getting rid of waste materials in the cells.
- Reduces inflammation in the body and also oxidative damage.
- It lowers cholesterol levels and reduces blood pressure.
- It increases testosterone levels while reducing leptin in the body.

Can You Drink Coffee While in Intermittent Fasting?
First, it is important to note that drinking very low to no-calorie drinks such as black coffee doesn't affect your fasting in any major way. This is due to the fact that a regular cup of black coffee only contains about 3 calories, traces of minerals, and very little protein content. Considering this very low nutritional content, drinking black coffee doesn't influence any notable metabolic change.
Can I Have Creamed Coffee While Fasting?
Adding ingredients such as milk and sugar to your coffee can significantly affect your intermittent fasting. This is because milk and sugar are high-calorie additives. Adding cream to your coffee while fasting beats the purpose of undertaking intermittent fasting in the first place.
When it comes to intermittent fasting, the general rule of thumb is to keep your calorie intake to below 50 grams per day.
In case you must add something to your coffee, then it is highly recommended that you stick to adding only one teaspoonful of coconut oil or heavy cream. This is because these additives don't affect your blood sugar levels.
2 Common Side-Effects of Intermittent Fasting
While IF offers numerous health benefits, it does have some common short-term side effects, which are often as a result of the body switching from burning sugar for energy to burning fat.
So, what are some of these common side effects?
1. Intermittent Fasting Effects on Poop
- Diarrhea
Diarrhea is one of the most common side effects of intermittent fasting and it can understandably prove to be very problematic. This side effect is commonly experienced by people who are new to fasting or got into the fasting after engaging in a diet high in carbs
So, why does intermittent fasting cause diarrhea?
There are various reasons why most people experience diarrhea when fasting. The first reason is that, as you get deeper into fasting, the digestive system tends to shut down. Thus when you consume food, it doesn't function and effectively and this causes food and nutrients to quickly move through your digestive system without being absorbed.
The second reason is that when you start intermittent fasting, your body experiences a drop in insulin levels. This signals to the kidneys to excrete excess water. If you had been drinking a lot of water, coffee, tea or any other drinks to minimize hunger pangs, then you are more likely to experience diarrhea due to this.
- Constipation
Constipation is another way intermittent fasting affects your poop. Our bowel movements move at different rates, and most people need to eat more often to keep things moving down there. Thus, when such people start fasting, there is less substance to move the previously digested food in the tract which leads to discomfort.
2. Headache, Dizziness, Mental Fog and Lethargy
All these side effects are usually as a result of reduced sodium levels. As stated earlier, fasting usually leads to reduced insulin levels in the body. Considering that insulin is responsible for water retention, the drop in insulin levels signals the kidneys to excrete excess water. This causes increased urination.
As a result, your body also loses sodium through urine. In addition, considering the fact that you aren't eating enough food to replenish lost electrolytes including sodium, magnesium, and potassium, your body's homeostasis is thrown off balance leading to these symptoms.
Which is Better, Intermittent Fasting vs Keto?
While intermittent fasting and keto are quite different, both offer similar health benefits. Both of these techniques have been proven to be effective in losing weight and managing various health conditions. Both increase the levels of ketones in the body by reducing insulin levels. However, the difference is in the way they work. The keto diet is more strict than IF.
While the keto diet is more about what types of food you eat, intermittent fasting is more about when you eat your food. IF is ideal for those people who are struggling to fight their cravings and tracking their daily calorie intake.
Can You Do Intermittent Fasting and Keto Together?
Most Keto experts agree that doing keto in tandem with intermittent fasting works perfectly in achieving weight loss and improving overall body health. While the keto diet helps to increase ketone levels in the body by burning fat in the body, intermittent fasting increases ketone levels by reducing insulin levels in the body. Thus, combining the two has been found to produce better results.
What Are the Benefits of Combining Keto and Intermittent Fasting Benefits?
- Increased Fat Loss
Combining a ketogenic diet plan with intermittent fasting has been found to help people burn more fat than when undertaking a keto diet alone. Numerous studies have shown that, own its own, intermittent fasting is very effective info shedding excess body fat.
In fact, a study conducted on 28 individuals found that those who used intermittent fasting to lose excess body fat, lost 7.3 pounds more fat mass than those on very-low-calorie diets. Therefore, by combining the fat-burning power of a keto diet plan and intermittent fasting, then you will be able to realize more body fat loss.
- Makes It Easier to Achieve Ketosis
By adding intermittent fasting to your keto diet, you will help your body to reach ketosis much faster than doing the keto diet alone. This is because when fasting, the body is able to maintain its energy balance by burning fat instead of carbs. This is the same basis upon which the keto diet works.
In case you are struggling to reach ketosis while on the keto diet, then you should consider including intermittent fasting to boost the process.
When Should I Try an Intermittent Fasting Keto Method?
Most experts don't recommend taking up intermittent fasting and a keto diet plan at the same time. This is because the drastic changes can cause significant shock to the body system. The body might be unable to deal with the interference caused by switching from using sugar as the primary source of energy to fat and the changes caused by intermittent fasting.
It is therefore recommended to start with keto, and then later on after being on the diet for some weeks or months, you can then take up intermittent fasting. This will provide your body enough time to start adjusting to the new conditions and better handle the changes brought about the effects of intermittent fasting.
Some have found great results with the addition of high intensity interval training. As always, it is important to talk to your health professional and a qualified fitness trainer before begining.
How Long Should You Intermittent Fast While On The Keto Diet?
The 16/8 method is considered the most effective intermittent fasting plan to use with a keto diet. This is considering the fact that to most people, going without eating for 12 to 16 hours and not eating during the nighttime hours is a normal habit. Therefore, people don't have to skip any meals when they include the 16/8 intermittent fasting in their keto diet plane.
When getting started with IF while on a ketogenic diet, it is recommended to delay your breakfast by one hour each day. By doing so, your body will start adapting to going for longer periods of time without feeding.
When it comes to how long you should practice intermittent fasting keto, most experts recommend doing it for a maximum of 6 months before you transition to a standard low-carb diet.
As you can see, combining keto and intermittent fasting benefits has significant health benefits that should be highly considered. However, as earlier mentioned, it is crucial to first consult your medical specialist to ensure that you are a viable candidate for the keto IF approach.
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