The ketogenic diet and intermittent fasting have more in common than you may believe. When combining the two practices, they may be able to synergistically work together toward common goals of fat loss and improved metabolic health.
Despite the differences in the diets, they have two big similarities: both increase ketone production and can also burn the body’s fat stores. In tandem they may help to expedite your weight loss goals.
But where do they fit in together? Practicers of intermittent fasting are using the technique to improve weight loss, insulin sensitivity and other health biomarkers.1 The keto diet targets many of the same goals, like helping to reshape metabolism and improve body composition.
If you’re trying to decide between one or the other, why not try both at the same time? Let’s look at some of the benefits of each, and how they can work together to encourage a healthy lifestyle.
The ketogenic diet has been around for several decades, but has gained increasing popularity over the last several years.2 While some diets encourage consumption of fewer calories, the ketogenic diet is based on low carbohydrate intake rather than focusing on calorie intake. Keto can be described as a low-carb, high-fat diet which induces production of ketones from fat, leading to a state of ketosis: the presence of ketones in the blood at greater than 0.5mM. This is much different than the traditional western high-carb diet.
Our bodies are biologically programed to run on a mix of carbohydrate and fat depending on what’s available.
Dietary carbohydrate gets taken up and used as energy via blood glucose (blood sugar), or it is stored as a molecule called glycogen in the liver. Glycogen is slowly released between meals to keep blood glucose energy levels stable. Once carbs are removed from the equation, the body eventually learns to use alternative fuel sources for energy as glycogen stores are depleted.
There are two ways to induce ketosis. The first, called endogenous ketosis, is when ketosis is triggered through diet or fasting. In this case, the body is making its own ketones, meaning the body is ketogenic. It can take days of fasting or weeks of dieting to achieve endogenous ketosis.
The ketogenic diet is often misconstrued by the masses as a high-fat diet that features bacon, butter, and oil as its main components. While you may choose to indulge in these particular types of foods, the main attribute of keto is that it requires dieters to consume little to no net carbs. If you’re on keto, you should aim for a carb intake around 50g per day—a really low amount.
The second was to induce ketosis is called exogenous ketosis. This means that ketones are introduced to the body from an external source, from ketone supplements like H.V.M.N. Ketone. This body is still in ketosis (because its blood ketone levels are elevated) but it’s not ketogenic (because the body isn’t producing its own ketones).
Several supplements exist on the market to raise blood ketones through exogenous means. The goal with these types of products is to spur a faster, deeper ketosis without the need to diet or fast.
There are medium chain triglycerides, or MCT oils, which are a special type of fat found naturally in coconut oil, palm kernel oil, and butterfat. They do not contain ketones, instead possessing a fat that’s readily converted to ketones. While there are many MCTs on the market, it's best to find one without artificial ingredients, and one that's low-carb (to help you maintain ketosis). H.V.M.N. MCT Oil Powder is pure C8—the world’s most ketogenic fat. It’s 100% natural with no additives, no artificial ingredients, and zero net-carbs.
Then there are ketone salts. Ketone levels rise marginally after using salts, from about 0.6mM - 1mm.3,4 And often, a high mineral intake is necessary to raise ketone levels, leading to GI issues and concern around the safety of long term high salt intake.
Finally, there are exogenous ketone esters. H.V.M.N. Ketone is the world’s first exogenous ketone ester drink, and can raise blood ketone levels up to 3mM - 6mM.3,5,6,7 It’s used by professional athletes, the US military and was even used to break a cycling world record.
The choice between relying on exogenous or endogenous ketosis depends on your health and performance goals.
Interestingly, the body and brain can both use ketones as energy (like glucose). That’s why there are subjective reports of increased focus and less brain fog from keto dieters and people using exogenous ketones.
These are also some of the subjective feelings reported by intermittent fasters, likely due to the increased ketone levels from carb-depletion.
Our menu accounts for everything from calories to macronutrients. Sign up now to receive this exclusive menu from keto diet experts.
Intermittent fasting is exactly what it sounds like: not eating for a certain period of time. On the surface, cutting out meals for a set period of time seems beautifully simple. But new research is advancing our knowledge of the best timing for meals and the helpful changes to our biology that occur during fasting.
When you consume carbohydrates, the pancreas begins to release insulin-triggering carb uptake and storage.
Virtually every meal we eat triggers a metabolic response in our body.
Carbohydrates in our food (and to a lesser extent, protein) trigger the release of the hormone. The insulin in turn tells the body to store any excess energy as glycogen or as fat for later use. Some of the fat is stored in the liver, but most of it becomes fat deposits in the body. Insulin also switches off the processes that release fat from fat deposits, meaning that fat is going into storage and not used as fuel.
When you practice intermittent fasting on the other hand, energy intake is lower, insulin levels begin to fall and fat burning increases.
By increasing the amount of time the body is in a fasted state, there will be more time to for the body to tap into stored energy. Across evolution, most species would regularly enter a fasted state. Predators tend to eat larger portions at one given time and may not consume food for several days. There is nothing wrong with occasionally fasting for longer periods of time and it actually has several health benefits (but of course, consult your doctor before doing this).
Simply put, restricting the amount of calories you consume will put the body into a fasted state.
There is a common belief that skipping a meal is bad for your metabolism or overall health. Truth is, we’re seeing more data support the idea of restricted eating. The three-meals-a-day convention has been standard in American diets for decades. But obesity has increased. Diabetes and pre-diabetes have also increased.
Obviously, something isn’t working.
In studies performed on animals,14 those in a fasted state had longer lifespans compared to those that did not fast. It seems the benefits of fasting can not only be seen short term, but over the course of a lifetime as well.
An interesting diet that mimics fasting is called the Prolon Diet. The idea is to really decrease insulin release while still providing nutrients. It’s a low-protein, low-carbohydrate, high-fat diet with calorie intake ranging from 770 - 1,100 calories per day. Studies have shown a fast-mimicking diet can improve biomarkers for aging, diabetes and cardiovascular disease.15,16
Besides benefits for body composition or weight loss, there are a number of advantages that accompany intermittent fasting.
Intermittent fasting has been a cultural pillar here at H.V.M.N. Employees regularly participate in intermittent fasting, and have cited more productivity as one of its benefits, along with the absence of daily slumps associated with spikes in insulin from eating carbs. But it’s not just employees at H.V.M.N. who fast—it’s an ancient tradition with many variances in schedules.
Unlike many other diets, intermittent fasting deals not with what you eat, but rather when you eat.
This dietary convention is all about timing rather than eating certain varieties of food. When you choose to partake in intermittent fasting, you are eating within a certain window of time. By forcing the body to stay in a fasted state for a longer period of time, the body will turn to fat stores to use for energy (since it doesn’t have carbs).
The body stores way more fat than carbohydrates, and will eventually learn to tap into those fat stores for energy. Simply choosing to eat in certain windows of time can have a positive long term effect on your body composition and overall health.22 Your body fat can decrease as well.
There are different variations of intermittent fasting, so it is not a one size fits all type of practice.
The most common method of intermittent fasting is choosing a certain times for food intake (sometimes called “feeding hours”).
You may choose to eat over a four, six, or eight-hour window. This means you only eat during this particular timeframe and the remaining hours of the day are spent fasting.
Some people fast for 16-hour periods, eating only between the hours of 12pm - 8pm, and not eating outside of that timeframe. Some do a 24-hour fast every week. Some of the most dedicated intermittent fasters will do a 36-hour fast every week. Employees at H.V.M.N. even did a seven-day fast.
Here are a couple ways to work eating windows and fasting windows into your normal eating schedule:
Some people may take their fasts a step further and may choose to only eat once per day. This becomes a 24-hour (or near 24-hour) fast. You should use your sleeping hours to your advantage, almost like free fasting time (unless you’re sleep-eating). A common way to do this is to consume your last meal at 8pm, then wait to eat until 8pm the following day. Often, this is referred to as one-meal-a-day or OMAD fasting.
Regardless of the eating window, the total caloric intake for the day should remain the same.
Some may argue that there are advantages to having a longer period of fasting, but your choice of eating window is entirely up to you. The best fasting protocol is the one that you stick to. Find a way to work this into your everyday schedule for the best, most consistent results.
It’s supremely important to stay hydrated while you fast. Though, some fasters consume only water during both shorter and longer fasts. Another popular beverage choice during a fast is black coffee, but this can be seen as a crutch because it reduces appetite.
Alternate day fasting (ADF) is a form of intermittent fasting, but takes a bit more of an extreme approach: no food for 24 hours every other day. However, alternate schedules allow for 500 calories to be consumed on fasting days, which have shown to be easier to stick with.23,24,25
No matter the protocol, ADF diets have shown positive results for weight loss.26 Interestingly, studies in animals showed that ADF may modulate risk factors for chronic disease, and can help retain muscle mass in humans (something of a concern with fasting).27,28
Longer water fasts can last anywhere from 36 hours to several days.
Studies in both animals and humans have suggested water fasts can have health benefits.
The ketogenic diet and intermittent fasting tap into similar metabolic pathways and so they should be able to work together synergistically
The obvious juxtaposition: keto is a form of long-term dieting with a specific macronutrient target, that therefore restricts what types of foods you eat. Intermittent fasting occurs in the short term and restricts only when you can eat—with no macro-rules in the eating windows.
However, as explored earlier with low-protein, high-fat, low-carb diets, focusing on keto during the eating windows may prolong the helpful metabolic pathways invoked by fasting. An interesting application is Peter Attia’s “Nothingburger,” in which he conducted a week long fast between two weeks of nutritional ketosis.
Both dieting methods can work toward the same goal: use fat stores for energy and put the body in a state of ketosis. Both deplete the body of glucose. If you’re intermittent fasting, it may be able to put you into a state of ketosis more quickly than dieting alone.
Very few studies look at keto and intermittent fasting together. However, as our understanding of the biology supporting both deepens, we can see clear synergies; this illustrates the two together can be a good combination.
Although starting a hybrid type of diet sounds complicated, it can be simplified very easily. Here’s a look at what a single day might look like if you’re on keto and intermittent fasting. Follow these steps for an example keto meal plan that could be employed while intermittent fasting.
6:00am: Wake up, drink water and/or black coffee.
9:00am: Drink another cup of coffee if you’re feeling especially hungry or low on energy.
12:00pm: Begin eating window with eight ounces of chicken breast and a salad with olive oil dressing and feta cheese. Other lunch additions include hard boiled eggs, salmon, and avocado.
3:00pm: Snack on a handful of almonds and some blueberries.
6:00pm: Eat eight ounces of fish accompanied by vegetables like Brussels sprouts, string beans or asparagus.
8:00pm: Blueberries or nuts as dessert, for the final food consumed of the day.
If you’re considering a week of intermittent fasting interspersed with your keto diet, here’s what that week might look like.
Monday: Feeding hours between noon - 8pm. If you exercise on Mondays, try a midday workout when you’re fully fueled. Enjoy your last meal at 8pm. Keto meals might include a smoked salmon and avocado plate, or a steak and sweet potato dinner.
Tuesday: Fasting day. No calories consumed until 8pm.
Wednesday: Try a fasted workout in the morning. Begin eating at noon—you’ll probably be hungry. Reward yourself with a big chicken BLT salad for lunch and cheese omelette for dinner.
Thursday: No workouts, no all-day fasting. Since energy requirements are less on these days, begin eating at noon and try a turkey, cheese and avocado wrap for lunch, then salmon and asparagus for dinner.
Friday: Maybe the fasted workout didn’t go your way. Today, try a workout later in the day, planning your last 8pm meal as one high in protein. Try roasted chicken paired with creamy broccoli.
Saturday and Sunday: Here is another opportunity to try an extended fast, if you’re feeling up for it. But if you’re working out, ensure to properly fuel until you fully become fat-adapted. Maybe a nice long run outside is an option here. And use Sundays to meal prep, making the rest of the week easier!
This is an extremely simplified version, but starting this style of diet does not have to be complicated. Eat keto-friendly foods in a predetermined window. In this case the standard eight-hour eating window was followed, however, you may choose to follow a shorter eating window if so desired.
Keto dieting and intermittent fasting can go hand-in-hand when done correctly. Both should encourage the body to enter a state of endogenous ketosis, and hopefully, boost the results.
But remember—this is a process. It’ll take a bit of time to find out the best schedule that fits your lifestyle. Don’t be afraid to experiment and adapt. The best diet plan is the one that you’re able to stick to.
Have you tried intermittent fasting combined with keto? Share your experience in the comments.
Subscribe for our list of 10 products to help you fast
|1.||Collier R. Intermittent fasting: the science of going without. CMAJ. 2013;185(9):E363-4.|
|2.||Walczyk T, Wick JY. The Ketogenic Diet: Making a Comeback. Consult Pharm. 2017;32(7):388-396.|
|3.||Stubbs, B.Cox, P.; Evans, R.; Santer, P.; Miller, J.; Faull, O.; Magor-Elliott, S.; Hiyama, S.; Stirling, M.; Clarke, K. (2017). On the metabolism of exogenous ketones in humans. Front. Physiol.|
|4.||O’Malley, T., Myette-Cote, E., Durrer, C., and Little, J.P. (2017). Nutritional ketone salts increase fat oxidation but impair high-intensity exercise performance in healthy adult males. Applied Physiology, Nutrition, and Metabolism, 1-5.|
|5.||Clarke, K., Tchabanenko, K., Pawlosky, R., Carter, E., Todd King, M., Musa-Veloso, K., Ho, M., Roberts, A., Robertson, J., Vanitallie, T.B., et al. (2012). Kinetics, safety and tolerability of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate in healthy adult subjects. Regul. Toxicol. Pharmacol. 63, 401-408.|
|6.||Shivva, V., Cox, P.J., Clarke, K., Veech, R.L., Tucker, I.G., and Duffull, S.B. (2016). The Population Pharmacokinetics of d-β-hydroxybutyrate Following Administration of (R)-3-Hydroxybutyl (R)-3-Hydroxybutyrate. The AAPS journal, 1-11.|
|7.||Cox, P.J., Kirk, T., Ashmore, T., Willerton, K., Evans, R., Smith, A., Murray, Andrew J., Stubbs, B., West, J., McLure, Stewart W., et al. (2016). Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes. Cell Metabolism 24, 1-13.|
|8.||Partsalaki I, Karvela A, Spiliotis BE. Metabolic impact of a ketogenic diet compared to a hypocaloric diet in obese children and adolescents. J Pediatr Endocrinol Metab. 2012;25(7-8):697-704.|
|9.||Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition. 2013;67(8):789-796. doi:10.1038/ejcn.2013.116.|
|10.||Hallböök T, Ji S, Maudsley S, Martin B. The effects of the ketogenic diet on behavior and cognition. Epilepsy Res. 2012;100(3):304-9.|
|11.||Sumithran, P., Prendergast, L. A., Delbridge, E., Purcell, K., Shulkes, A., Kriketos, A., & Proietto, J. (2013). Ketosis and appetite-mediating nutrients and hormones after weight loss. Eur J Clin Nutr, 67(7), 759-764.|
|12.||AJMC. Type 2 Diabetes: Changing the Paradigm From Management to Reversal. https://www.ajmc.com/contributor/sarah-hallberg-do-ms/2017/04/type-2-diabetes-changing-the-paradigm-from-management-to-reversal. Accessed February 14 2019.|
|13.||Dashti HM, Mathew TC, Hussein T, et al. Long-term effects of a ketogenic diet in obese patients. Exp Clin Cardiol. 2004;9(3):200-5.|
|14.||National Institute on Aging. Longer daily fasting times improve health and longevity in mice. hhttps://www.nia.nih.gov/news/longer-daily-fasting-times-improve-health-and-longevity-mice. Accessed February 14, 2019.|
|15.||Brandhorst S, Choi IY, Wei M, et al. A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell Metab. 2015;22(1):86-99.|
|16.||Wei M, Brandhorst S, Shelehchi M, et al. Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Sci Transl Med. 2017;9(377)|
|17.||Walker G, Houthoofd K, Vanfleteren JR, Gems D. Dietary restriction in C. elegans: from rate-of-living effects to nutrient sensing pathways. Mech Ageing Dev. 2005;126(9):929-37.|
|18.||NIH Research Matters. Fasting increases health and lifespan in male mice 2018. hhttps://www.nih.gov/news-events/nih-research-matters/fasting-increases-health-lifespan-male-mice. Accessed February 14, 2019.|
|19.||Patterson RE, Sears DD. Metabolic Effects of Intermittent Fasting. Annu Rev Nutr. 2017;37:371-393.|
|20.||Moro T, Tinsley G, Bianco A, et al. Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. J Transl Med. 2016;14(1):290.|
|21.||Lutas A, Yellen G. The ketogenic diet: metabolic influences on brain excitability and epilepsy. Trends in neurosciences. 2013;36(1):32-40. doi:10.1016/j.tins.2012.11.005.|
|22.||Tinsley GM, La bounty PM. Effects of intermittent fasting on body composition and clinical health markers in humans. Nutr Rev. 2015;73(10):661-74.|
|23.||Klempel MC, Bhutani S, Fitzgibbon M, Freels S, Varady KA. Dietary and physical activity adaptations to alternate day modified fasting: implications for optimal weight loss. Nutr J. 2010;9:35.|
|24.||Anderson JW, Konz EC, Frederich RC, Wood CL. Long-term weight-loss maintenance: a meta-analysis of US studies. Am J Clin Nutr. 2001;74(5):579-84.|
|25.||Das SK, Gilhooly CH, Golden JK, et al. Long-term effects of 2 energy-restricted diets differing in glycemic load on dietary adherence, body composition, and metabolism in CALERIE: a 1-y randomized controlled trial. Am J Clin Nutr. 2007;85(4):1023-30.|
|26.||Varady, K. A., Bhutani, S., Klempel, M. C., Kroeger, C. M., Trepanowski, J. F., Haus, J. M., . . . Calvo, Y. (2013). Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial. Nutrition Journal, 12(1). doi:10.1186/1475-2891-12-146|
|27.||Johnson JB, Summer W, Cutler RG, et al. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Radic Biol Med. 2007;42(5):665-74.|
|28.||Varady, K. A. (2011). Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? Obesity Reviews, 12(7). e593–e601.|
|29.||Alirezaei M, Kemball CC, Flynn CT, Wood MR, Whitton JL, Kiosses WB. Short-term fasting induces profound neuronal autophagy. Autophagy. 2010;6(6):702-10.|
|30.||Castello L, Froio T, Maina M, et al. Alternate-day fasting protects the rat heart against age-induced inflammation and fibrosis by inhibiting oxidative damage and NF-kB activation. Free Radic Biol Med. 2010;48(1):47-54.|
Once a week, we'll send you the most compelling research, stories and updates from the world of human enhancement.
These statements have not been evaluated by the FDA. Our products are not intended to diagnose, treat, cure, or prevent any disease.
© 2019 HVMN Inc. All Rights Reserved. H.V.M.N.®, Health Via Modern Nutrition™, Nootrobox®, Rise™, Sprint®, Yawn®, Kado™, and GO Cubes® are registered trademarks of HVMN Inc. ΔG® is a trademark of TΔS® and used under exclusive license by HVMN Inc.