Keto And Intermittent Fasting: What You Need To Know Before Combining The Two Diets To Lose Weight

Keto And Intermittent Fasting

Keto And Intermittent Fasting

Updated on 5/18/2024
Martin AlvarezBy Martin Alvarez
Nutritionist/Dietitian Professional Guide
Learn More about Martin Alvarez

When you combine these two fashionable tactics, it is said that you will get superior outcomes. But can we continue with this combination strategy and maintain it for the foreseeable future?

Combining keto and intermittent fasting requires consuming a high-fat diet with minimal carbohydrates at specific time windows throughout the day.

It is becoming increasingly popular with replacing carbohydrates with fats to reduce carbohydrates in the diet. However, suppose you have successfully lost weight by following this well-known method, referred to as the ketogenic diet (or keto for short). In that case, you may consider taking things up a notch and combining the ketogenic diet with intermittent fasting to break through a weight loss plateau or improve your results. Is this something you ought to test out for yourself?

It may, but you should know that this combination method has not been tested and proven effective in helping you lose weight. There is consensus among specialists that you should try something else if you want to lose weight. Still, given how little study there is on the topic, you may want to consider it seriously before diving into this eating strategy.

According to Lori Shemek, Ph.D., a nutrition and weight loss expert in Dallas and author of How to Fight FATflammation, the combination of the two diets first gained popularity when intermittent fasting expert Jason Fung, MD, author of The Obesity Code, recommended using keto as a foundation with fasting. Since then, combining the two diets has become increasingly common. According to Dr. Shemek, celebrities such as Halle Berry have been known to follow the low-carb diet.

First, let's go through the specifics of each diet.

What Are Some Of The Ketogenic Diet's Foundational Principles?

keto diet

keto diet

According to findings from earlier studies, the ketogenic diet was first developed by researchers in the 1920s to assist parents in managing their children's epileptic seizures. According to the Epilepsy Foundation, the "traditional" ketogenic diet or the "long-chain triglyceride diet" advocates for consuming 3 to 4 grams (g) of fat for every 1 g of carbohydrates and protein. This variation of the ketogenic diet is also known as the "low-carb" diet.

In its modern iteration, the ketogenic diet is quite different from traditional keto in that it consists of a diet that is rich in fat, has a reasonable amount of protein, and has few carbohydrates. As a general rule, you should try to consume between 20 and 50 g of net carbohydrates per day (carbs less fiber), which varies, depending on your needs, and your specific requirements determine the amount you eat. Fat accounts for around 80 percent of the calories you consume each day.

On a standard food list for the ketogenic diet, the majority of carbohydrate-containing foods, including some nutritious options like whole grains high in fiber and the vast majority of fruits, are discouraged in favor of foods high in fat, such as avocados, olive oil, grass-fed beef, and even bacon on occasion.

This eating plan aims to help your body switch from using glucose (or carbohydrates) as its primary fuel source to using fat instead of carbs as its primary fuel source. Ketosis, often known as being keto-adapted, is the name given to this condition.

The keto diet is among the best diets for reducing weight quickly in the short term. On the other hand, the critics of the keto diet point out that there do not appear to be many long-term studies (a study that lasts for at least two years) examining the effectiveness of keto for weight loss in individuals.

More research is necessary to support many of the claims that keto can treat health conditions other than epilepsy, according to an article published in the European Journal of Clinical Nutrition in August 2013. These conditions include cancer, high blood pressure, polycystic ovary syndrome (PCOS), diabetes, and neurological diseases such as Alzheimer's. Keto is also critical for epilepsy sufferers to be aware of since it can treat the condition.

How Exactly Does One Go About Doing An Intermittent Fast?

Intermittent Fast

Intermittent Fast

Another method for losing weight is intermittent fasting, in which you schedule specific periods during which you will not consume any food. The practice of intermittent fasting, which some people refer to as IF, may be carried out in several different ways.

It is known that some individuals choose to follow the popular 5:2 intermittent fasting pattern because they usually eat for five days and then restrict their calorie intake to a deficient level for two days, consuming about 500 calories per day on fast days. Some people go a whole day without taking in any food. While some could follow a time-restricted eating plan, such as eating just every 8 hours and then going without food for 16 hours,

According to a review published in March 2017 in the journal Behavioral Sciences, some exciting research on humans is emerging in the field of intermittent fasting (IF). This research includes the approach's role in treating obesity and insulin resistance, which is the hallmark of type 2 diabetes. However, the authors of that study concluded that there is "a dearth of high-quality data" about the effects of IF on one's health and that it is still unknown which sort of IF is the most effective to follow.

Most research on intermittent fasting (whether for weight reduction or another purpose) has been conducted on animals rather than people or has been of limited duration.

keto and intermittent fasting

keto and intermittent fasting

The ketogenic diet and intermittent fasting (IF) may assist with weight reduction in the short term; however, since both diets are so restricted, they are not appropriate for everyone. What about putting them together, though? Would having two be preferable to have only one?

To begin, combining the two strategies is recommended by the opinions of several knowledgeable individuals. The ketogenic diet causes an increase in the body's ketone levels, and the body also produces more ketones while starving itself. When the body is in a condition of nutritional ketosis, glucose will be used for energy by the brain less and less. According to Dominic D'Agostino, Ph.D., associate professor at the University of South Florida in Tampa and creator of, the shift into a fasting state (ketogenic state) throughout the day ultimately becomes smooth after eating low-carb or ketogenic for a few weeks.

In the Functional Ketogenics Program at the Cleveland Clinic, practitioners provide patients with advice to help them achieve their goals. According to Logan Kwasnicka, a licensed medical assistant at the Cleveland Clinic in Ohio, "Adding intermittent fasting may take things up to the next level," he adds. The Clinic is located in Cleveland. Because individuals who practice intermittent fasting tend to consume fewer calories overall, the next stage may consist of breaking through a weight reduction plateau. It may also be a logical step from a keto diet for those who feel full eating so much fat (the state of ketosis may also lower appetite) and aren't troubled by the reduction of their eating window.

Who Should Consider Attempting A Keto Approach With Intermittent Fasting?

keto and intermittent fasting

keto and intermittent fasting

Anyone following the keto diet for more than two weeks and wanting to add IF may do so as long as they have received approval from their healthcare team. Kwasnicka warns that it is risky to encourage people with prediabetes or diabetes to go without food for an extended period. However, the ketogenic diet has grown more popular among individuals who suffer from prediabetes or diabetes. It's doubtful that you'll be a suitable fit for this combination diet plan if you have a chronic renal illness, a history of eating disorders, are now having active cancer treatment, are pregnant or nursing, or have had eating problems in the past. Even particular diets, such as ketogenic and intermittent fasting, could not be suggested for these groups. Verify this information with your healthcare team.

Also, if you are presently following the keto diet, she adds that you do not need to add in IF if you are pleased and feel good with the way that you are eating while on the keto diet.

The Correct Way To Begin A Ketogenic Diet While Observing Intermittent Fasting

keto and intermittent fasting

keto and intermittent fasting

At the Cleveland Clinic, the medical staff does not recommend that patients simultaneously begin the ketogenic diet and intermittent fasting (IF). According to Kwasnicka, "It's a major shock to your system to switch from glucose as fuel to ketones, and applying IF is a substantial adjustment." [C]hanging from using glucose as fuel to using ketones is a significant change. People often begin with ketogenic diets for this reason, and they could think about intermittent fasting after being on a diet for a few weeks to a few months.

Additionally, it is essential to determine the most appropriate moment. Fasting for 12 to 16 hours is something that Kwasnicka recommends for their patients. It is a natural habit for many individuals to not eat for 12 hours a day (for example, from 7 p.m. to 7 a.m.). Thus they do not need to miss meals to maintain this routine.

Shemek says that to get your body used to last more extended periods without eating, you should begin by postponing breakfast by an hour at first and then gradually increasing the amount of time you go without eating. According to a study that was published in August 2018 in the American Journal of Physiology-Endocrinology Metabolism, eating breakfast leads to better cognition, as well as improved metabolism and insulin sensitivity. When you've adjusted to your new eating pattern, reintroduce breakfast earlier in the day and extend your overnight fasting time. This is because breakfast leads to better cognition, improved metabolism, and insulin sensitivity. She suggests practicing keto-IF for no more than six months and then shifting to a more conventional low-carb diet after completing keto-IF for that time. This is about the length of time that one should be on keto-IF.

An Example Menu For Those Following The Ketogenic Diet And Intermittent Fasting

keto and intermittent fasting meal plan

keto and intermittent fasting meal plan

If your healthcare team has given you the go-ahead to take this combination strategy, you may wonder what foods you'll be allowed to consume during this time (and when). Your intuition is spot on: the time of your meals is the most important consideration with this diet.

Shemek has provided the following example of what three days on a diet may look like if they are followed by time-restricted eating in the form of a 16-hour fast followed by an 8-hour meal pattern. There are many other methods to fast, and thus this method is not the only way to conduct intermittent fasting (IF). You may, for instance, choose to go without food for 12 or 14 hours each day.

You'll find that snacks are utterly discretionary with this approach. Depending on your health condition, you should keep in mind the amount of carbohydrate, protein, and fat you need to consume to remain in ketosis at any given time. You may estimate such ratios with a certified dietitian knowledgeable about the keto intermittent fasting method.

Day 1

10 a.m. Breakfast consists of black Coffee, scrambled eggs topped with avocado slices, and water throughout the morning.

1 p.m. Lunch A substantial portion of mixed greens topped with two tablespoons of olive oil, one tablespoon of vinegar, and 3 ounces (oz) of grilled salmon

3 p.m. Snack (optional) ¼ cup Macadamia nuts

6 p.m. Dinner A chicken leg, complete with the skin, a quarter cup of cooked wild rice, and two cups of zucchini cooked in olive oil are included in this dish.

Day 2

10 a.m. A keto-friendly smoothie, plain hot tea, and water for the whole morning

1 p.m. Lunch 3 ounces of chicken breast that has been grilled, half a plate of broccoli and cauliflower seasoned with one tablespoon of olive oil, and one entire avocado

Snack time at three o'clock: unsweetened coconut chips (optional)

6 p.m. Dinner On a bed of Asian coleslaw, 3 ounces of tuna that has been seared and then cooked in olive oil, topped with a drizzle of olive oil and sesame seeds

Day 3

10 a.m. Coffee black with keto chia pudding and water throughout the morning

1 p.m. Lunch Three egg omelets packed with half a whole bell pepper and one cup of spinach, cooked in one tablespoon of olive oil, topped with one-half of an avocado, and served with one-half cup of sliced tomatoes.

Olives as a snack (optional) at three o'clock

6 p.m. A giant kale salad (three cups of kale) with three ounces of shrimp, three tablespoons of olive oil, and your choice of vinegar on top

Possible Positive Effects On One's Health From Following An Intermittent Ketogenic Diet

keto and intermittent fasting meal plan

keto and intermittent fasting meal plan

There is no data on the health implications of combining the ketogenic diet with intermittent fasting (IF). Still, performing both at the same time would increase ketone levels. According to Dr. D'Agostino, this might speed up losing weight. However, he notes that individuals react in various ways, suggesting that this may not be true in all cases.

Shemek recommends ketogenic or intermittent fasting and ketogenic combination diets to all her clients. "Most of my customers are overweight and on the verge of developing diabetes. They can readily adhere to the intermittent fasting and ketogenic diet plans after they have seen and experienced the benefits of eating in this manner, which include regulating their blood sugar levels. She argues that the fact that the joint strategy was successful strengthens their commitment to the project.

In addition to being examined for their effects on weight reduction, low-carb intermittent fasting diets are now being investigated for their impact on cognitive health. According to Richard Isaacson, MD, director of the Alzheimer's Prevention Clinic at Weill Cornell Medicine and NewYork–Presbyterian in New York City, doing a low-carb, time-restricted intermittent fasting (IF) diet may be beneficial for "calming down insulin pathways and letting the brain benefit from cleaner burning [ketone] fuel," which may offer benefits for people who have Alzheimer's disease.

Dr. Isaacson fasts for 16 hours and eats just once every eight hours on his own time, four or five times every week. According to him, this method may also assist in preventing the formation of fat around the waist. According to what he has said, "a larger belly [may] signify a lesser memory area in the brain." According to a study published in January 2012 in the British Journal of Radiology, people with more visceral fat (belly fat) are at greater risk of developing chronic diseases such as heart disease and type 2 diabetes.

Intermittent Fasting And The Ketogenic Diet: Are There Any Risks?

keto and intermittent fasting meal plan

keto and intermittent fasting meal plan

D'Agostino believes that regarding long-term hazards, "people with seizure disorders," which the ketogenic diet was first meant to treat, have been on a diet for decades and exhibit excellent health while remaining on it. However, the success of any diet is entirely dependent on the foods that are consumed. A keto diet high in bacon and butter is not the same as one high in avocado and olive oil, and a keto diet that is not carefully planned might lead to nutritional deficiencies. If you take the restriction to its extreme, you run the risk of losing too much weight or lean mass (muscle) due to the substantial reduction in calories you experience due to adding IF to your diet. Daily consumption of protein at a rate of 1 gram per kilogram of body weight is what he suggests doing to preserve muscle mass.

Conclusions and Recommendations Regarding the Use of the Ketogenic Diet in Conjunction with Intermittent Fasting

The keto diet, a low-carbohydrate, high-fat diet, and intermittent fasting, which limits the amount of time spent eating each day, are restrictive diets. Because there is a preliminary study done on each diet on its own, in addition to this combined plan, it isn't easy to know precisely what you are getting into whether you attempt any one of them on its own or all of them together.

If you decide to try the diets, you should be aware that they are pretty restricted diets, which means that it may be difficult for you to maintain the low carb count and the constrained eating window. Even youngsters who follow the ketogenic diet to bring their epilepsy under control have difficulty sticking to the regimen.

Consult with your medical professionals before considering combining keto and intermittent fasting diets. Your healthcare provider can assist you in determining whether or not this integrated eating plan is a good fit for you. The doctor will then be able to assist you in adjusting any medications that are currently being taken for you to increase your chances of success in the safest way possible to improve your chances of success.