The most common goal for people to try intermittent fasting or the keto diet is weight loss. However, modern eating trends are focusing on the merger of the keto diet and intermittent fasting. The main purpose of this combination is to reach ketosis, which is a state where you burn mostly fat instead of glucose for energy (1).
But is it really effective? And what are prolific keto fasting hours that help you shed calories? This review is going to delve into the best fasting hours to reach ketosis, how to remain in it after fasting, why you may not get into ketosis even though you barely eat any carbs, and the possible side effects of this combo.
Before you create your personal keto intermittent fasting meal plan, you should learn about the keto diet briefly and determine what the perfect fasting hours are that will help you attain ketosis.
The ketogenic diet reduces the number of carbs eaten per day. The keto diet is rich in fat, moderate in protein, and very low in carbohydrates. The standard keto diet encompasses 70% to 80% energy from fats, 10% to 20% from proteins, and 5% to 10% from carbohydrates.
During the keto diet, a person aims to achieve the state of ketosis. In simple words, it’s the state in which your body starts to use mostly fat for energy instead of glucose (1).
Intermittent fasting is one of the common ways to reach ketosis. The most popular keto fasting hours are in 16:8 fasting. This fasting involves eating during an 8-hour window and abstaining from food for the remaining 16 hours of each day.
Great samples of 8-hour eating windows are:
By reaching ketosis, you may support your weight loss process as your body is going to use fat for energy, including stored fat if you’re in a calorie deficit. Some people feel that keto diets make them feel less hungry, which leads to eating less food (1). A 16:8 fast is usually doable for beginners as it involves fasting hours while you sleep, but you can work your way up to it by starting with a 12- or 14-hour fasting window.
However, does this mean anyone can merge intermittent fasting and keto? Of course not. You should always consult your healthcare provider before you make any major diet or lifestyle changes. Keto and intermittent fasting aren’t safe or appropriate for everyone.
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The Cleveland Clinic suggests that you may be able to get into ketosis faster on a keto diet with intermittent fasting, such as 16/8, which requires not eating for 16 hours and then consuming food during the remaining 8 hours (1).
However, not everyone can fast, such as individuals with the following health conditions:
Moreover, breastfeeding women, or those who want to get pregnant or are pregnant already, should avoid intermittent fasting and any restrictive diet. Children under the age of 18 also need to abstain from it (2). Anyone with any health conditions or who is taking medication should talk to their doctor before they make any major diet changes or attempt to fast.
Why is this? Because both the ketogenic diet and fasting offer potential benefits and risks. You’ll learn about them in this review. In addition, the number one potential benefit is already clear – the keto diet and fasting may help with weight loss.
Read more: Best Foods to Break a 3-Day Fast: What to Eat to Break a Fast
Yes, a 16-hour fast should put you in ketosis. However, different people have different experiences. In addition, not everyone should combine methods to reach ketosis. People can reach ketosis after two to four days once they start to eat fewer carbs (around 20 to 50 grams daily).
Many factors affect the speed of entering ketosis:
Fasting on keto for beginners is basically the 16:8 hour fasting schedule. More experienced fasting practitioners often experiment with more advanced fasting windows such as a 24-hour fast. Again, you need to talk to your doctor before you try any of the intermittent fasting schedules, even those that seem easy for you.
Intermittent fasting with keto offers different schedules, but the most popular are 12- to 16-hour fasts. If your paramount goal is to lose weight, then the 16:8 fasting regimen is a popular one that can help create a calorie deficit. Most people only have time for 2 meals and perhaps a snack during an 8-hour eating window, which can help reduce your overall calorie intake if you normally eat 3 full meals.
If you’re a beginner and your doctor tells you to start with a 12-hour fast, you’ll start with this option, and once your body gets used to it, it will be easier to work up to a 16-hour fast.
It may be even better for you as fasting in general is already stressful to your body, particularly in the modern world where food is available all the time. We’re no longer hunting for animals and aren’t actively moving all day long.
Your body is accustomed to eating once you get slightly hungry and when you avoid food for a longer period, this can put your body under stress. Therefore, starting with a 12-hour fast may be beneficial for you as a newbie.
The most popular fasting schedule for keto is anywhere between a 12-hour and 16-hour fast. Your body may already enter ketosis after just 12 hours of fasting (3).
As previously referenced, these fasting schedules are easy to fit into most people’s lifestyles and perfect for those who are just starting. Most of your fast will occur during sleep, and the next day you’ll break it with a nice meal at 10am for example.
If you’re not sure which option is better for you, feel free to discuss it with your doctor first. It’s worth noting that skipping meals and limiting calories can be dangerous for people with certain health conditions (those who are taking medications for blood sugar or have heart disease or diabetes).
Carbs are certainly the most fundamental source of energy. By drastically limiting the number of carbs you consume, you increase the portion of protein and fat. One of the reasons why you may not achieve ketosis with no carbs is because you’re eating too much protein. Protein can be converted by the body into glucose.
Other factors that interfere with your entering ketosis or weight loss could be:
As you can see, many factors impact the possibility of reaching ketosis or your weight loss results. Even with a little carb consumption, it’s possible that no effects will be attained. Achieving your weight loss goals involves many different lifestyle and health factors and you should talk to your healthcare provider to get individualized advice.
Once the lazy keto intermittent fasting or more advanced version of it is over, you can still remain in ketosis. The best way to continue this journey involves eating fewer carbs during your eating window. Ketogenic diets usually allow between 20-50 grams of carbs per day.
It’s important to eat healthy fats, such as those from plant-derived oils, nuts, seeds, avocados, and oily fish. Regular exercise should be a part of your daily schedule. You should also drink plenty of water as this helps you reduce your appetite and gives you more energy. Work on your sleep – the better the quality, the lower your stress levels.
And finally, you should create a meal plan that perpetuates an ideal ketosis level for weight loss.
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Following this diet long-term may contribute to the following problems with your health:
The potential benefits include:
People who want to lose weight may be pleased to see notable results from the keto diet. However, it’s difficult to define how long this diet can be helpful and whether it’s safe enough as a sustainable diet. It’s always best to consult your healthcare provider to help you decide what’s right for you.
Lots of carbs can be found in hearty products, such as lentils, fruits, whole grains, legumes, vegetables, non-starchy vegetables, yogurt, berries, and oats. They help your body get all the primary vitamins and minerals and their reduction may lead to nutrient deficiency.
Read more: Fasting Until 4pm: Pros, Cons, And How To
To get into ketosis in 24 hours, you may need to increase your fat intake, increase your physical activity, and ensure you don’t consume more protein than required, cut down all the added sugars and processed snacks, try intermittent fasting (the fastest way to get into ketosis), start sleeping enough, and make sure you don’t have too much stress in your life.
If you feel stressed all the time, it’s important to talk to a mental health specialist who can guide you in your healing journey.
Without intermittent fasting, it may be impossible to get into ketosis within the first 24 hours. It usually takes two to four days to enter ketosis. In addition, if you’ve eaten a lot of carbs the days before your keto diet, it may take longer to reach this state as your body will need to exhaust its glucose stores first.
24 hours may be enough to reach ketosis if you try intermittent fasting and drastically cut down your carb intake. If there’s no fasting, then people usually need more time to enter ketosis – for some people, it can be two days, but for others, much longer. Your age, metabolism, eating habits, and physical activity also impact the time it takes to enter ketosis. Yes, too much protein can prevent ketosis. The keto diet is intentionally moderate in protein as it can be converted into glucose by the body when carbohydrates aren’t available. In many situations, not eating enough carbs can sabotage your ketogenic diet. As you start to drastically reduce your carb intake, you can face different side effects, such as dizziness, weakness, headaches, or fatigue. Some people strive to continue anyway, while others may quit the keto diet as the side effects could be too heavy for them. You should try a more gradual reduction until you get to where you feel comfortable. If you eat no carbs for a week, your body enters ketosis, breaking down fat into ketones for energy. This can promote the weight loss process as long as you’re also in a calorie deficit, but some of the effects may be short-term. However, you may encounter some risks too: headaches, constipation, or muscle cramps (7).Frequently Asked Questions
Is 24 hours enough for ketosis?
Can too much protein prevent ketosis?
What is sabotaging my keto diet?
What happens if you eat no carbs for a week?
What are prolific keto fasting hours? You now know that ketosis is a way to break down your fat and use it for energy instead of glucose. This may help with weight loss and associated health improvements. No studies have highlighted the long-term effects of the ketogenic diet entwined with intermittent fasting.
But for now, it’s understood that the most popular fasting hours for keto are a 16:8 fasting regime, where you abstain from food for 16 hours, leaving an 8-hour eating window.
You can also reach ketosis without fasting by drastically cutting down on your carb intake, increasing your fat intake, and improving your physical activity levels. Good sleep and stress management also impact the ketosis state, in addition to age, metabolism, and the choice of foods you’ll be eating.
Before you start any keto fasting journey, you should contact your doctor to confirm that it’s safe for you.
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