The ketogenic diet is a low-carbohydrate diet, but not any old low-carb diet. It’s not a diet where you just cut down on your carbs and let the rest take care of itself.
Rather, it’s a diet with a low – very low – carb intake, but where you replace the carbs with fat. The ketogenic diet is just as much a high-fat diet as it is a low-carb diet. The exact numbers can differ a bit depending on who you ask, but a standard ketogenic diet provides about 80% of the energy in the form of fat, and less than 5% in the form of carbohydrate.1 2 That doesn’t leave a lot of calories to spend on protein. The ketogenic diet isn’t normally a high-protein diet. We will discuss why later on.
In this article, you will learn everything you as an athlete or just an average gym-goer needs to know, if you are considering trying out a keto diet.
Maybe you are already on a ketogenic diet? If that is the case, the article will hopefully offer you further insight into how and why it works or doesn’t work for various athletic endeavors.
We will take a close look at the mechanisms behind ketosis, and how that unique metabolic state affects your body. You’ll learn how both endurance training and strength training work without carbohydrates, and whether or not the ketogenic diet is associated with any health risks.
First a Little Background and History
You might have heard about the ketogenic diet as a weight loss method. That’s probably how most people first come into contact with it, but the ketogenic diet was actually developed as a method to treat epilepsy once upon a time.
During the early 1920s, researchers discovered that a diet with minimal amounts of carbohydrates and a lot of fat successfully helped children with epilepsy to control their condition. In 1925, doctors reported that almost all patients showed significantly reduced symptoms, and 50% were completely relieved of seizures, after adopting a ketogenic diet.3 When seizure medications were introduced, the ketogenic diet as epilepsy treatment kind of faded into obscurity for decades. Lately, it has made a comeback as an adjuvant treatment to the primary treatment, when medications alone won’t do the trick.
Keto as a way to lose weight became popular during the 1970s, with Robert Atkins book Dr Atkins Revolution. In the book, he described various diet plans based on the low-carb diet he used treat overweight patients. The book became a best-seller, with movie stars and other celebrities embracing the diet. Physicians and scientists weren’t as impressed, condemning it and the methods Atkins described as scientific nonsense and potentially harmful.4 This likely contributed to the diet not achieving the global popularity Atkins probably desired and even expected.
Not until 1992 did Atkins get his revenge. That’s when the new, revised version of his book, called Dr Atkins New Diet Revolution, was published. It quickly entered the New York Times best-seller list, and parked there for more than 6 years. That book is one of the major things that made low-carb diets as popular as they are today. During the 1990s and continuing into the 2000s, low-carbohydrate diets, including the more restrictive ketogenic diet, became some of the most popular and wide-spread weight loss methods.
Lately, the ketogenic diet has garnered interest in the athletic community and in exercise research. A number of studies have demonstrated that a ketogenic diet can be a valid alternative even for high-level athletes. That’s quite the turn-around from the carbohydrate enthusiasm of earlier decades, which advocated the need for an athlete’s diet to consist primarily of carbohydrate, without which performance would be next to impossible.
How Does Keto Work?
The main purpose of a ketogenic diet is to get you into KETOSIS. Ketosis is a metabolic state where you don’t have a lot of glucose in your blood. It can be caused by fasting or starvation, planned or unintentional, or by deliberately avoiding dietary carbohydrate.
When you remove carbohydrates from your diet, your adipose tissue, your body fat, releases large amounts of fatty acids. The liver metabolizes these fatty acids along with any available carbohydrates, producing substances called beta-Hydroxy beta-methylbutyric acid, acetoacetic acid, and acetone. These substances are ketone bodies, and your body and your brain can use them as fuel instead of glucose.
It takes a while for your body to acclimatize to the fact that there aren’t any carbohydrates available any more and to accept this new fuel. During this time, you might notice that both your body and your brain won’t function as usual. You can feel tired and slow and lethargic. After this initial phase, both your muscles and your brain adapt to the new fuel and learn to use the ketone bodies much more efficiently. This means that you can function normally during daily life and physical activity again. Your brain never stops using glucose to fuel itself completely, but your liver can synthesize that amount on it’s own, even when you are in ketosis and don’t eat any carbohydrates.
Being in ketosis means that your blood ketone levels are elevated above normal, between 0.5 and 3.0 millimoles per liter (mmol/L). You can obtain these levels through fasting, intensive and prolonged physical activity, or through a low-carbohydrate diet. There are two types of ketosis. Physiological ketosis, which you enter during a fast or post-exercise after an extreme workout, and nutritional ketosis. Your reach the latter by manipulating your diet.
Ketosis is not the same as ketoacidosis, and the two shouldn’t be mixed up. Ketoacidosis is a pathological condition where blood ketone levels rise to 25 mmol/L and arterial pH drops. This can happen during uncontrolled diabetes, for example. Early medical literature did not make any distinction between ketoacidosis and ketosis, instead treating both as a pathological state.
Ketogenic and Low-Carbohydrate Diets: Are They Effective for Weight Loss?
No one can deny the popularity of low-carb diets when it comes to weight loss. However, the average weight loss diets relying on a reduced carb intake aren’t proper ketogenic diets. Instead, they usually are more general low-carb diets, with a lot of protein rather than a high fat content. In any case, mainstream media has helped propagate going low-carb as an effective way to lose weight. Sometimes, calories are forgotten with the focus being to the carbohydrates alone.
Each and every diet that accomplish weight loss, do so by reducing the amount of calories you eat and by inducing an energy deficit. The ketogenic diet is no exception.
Several large-scale studies have examined the effects of low-carb and ketogenic diets and how effective they are for losing weight.5 6 The results show that carbohydrate restriction is at least as effective as diets that advocate a low-fat approach. One of the most prominent studies demonstrated that the ketogenic Atkins diet is just as effective for weight loss as low-fat diets, calorie restrictive diets and regular non-ketogenic low-carb diets. In addition, the ketogenic approach improved cholesterol levels and insulin kinetics just as well as the other diets.
A meta-analysis from 2013 with around 1,500 subjects concluded that a low-calorie ketogenic diet can lead to greater weight loss than a low-fat diet, both at 12 and 24 months.7 The differences were anything but large, though, less than a kilogram compared to an isocaloric high-carbohydrate diet. That is a statistically significant difference, but maybe not a clinically significant one.
Current research does not support the notion that low-carb diets or ketogenic diets are inherently superior to any other type of calorie restriction providing varying amounts of carbohydrates. Avoiding carbs does seem to be at least as effective as counting calories, however, if weight loss is what you’re aiming for.
In the end, you can’t get around the fact that caloric balance drives weight loss. You have to eat fewer calories than you expend to lose weight, regardless of whether you eat a high carb diet or a ketogenic diet. Many find that they don’t have to keep track of every single calorie with a ketogenic diet, but that their food intake regulates itself, resulting in automatic weight loss.
Dietary fat is satiating through a number of mechanisms. A diet rich in fat increases feelings of fullness and depress appetite by releasing peptide hormones called cholecystokinin, glucagon-like peptide, and peptide YY.8 9 They tell your gut and your brain that you are full. In addition, a diet with a lot of fat makes food travel more slowly through your intestines, both because of the fat content itself and because of the previously mentioned hormonal signals.
Carbs don’t promote feelings of fullness to the same extent. This makes the ketogenic diet possibly advantageous when it comes to spontaneous regulation of food intake, leading to weight loss. Speculation that lower insulin levels due to the absence of dietary carbohydrate cause weight loss regardless of energy intake lacks or has very limited evidence. Strictly controlled trials demonstrate that a ketogenic diet does not have any apparent and inherent metabolic advantages.10 The ketogenic diet increases energy expenditure a bit, because of the energy cost of converting protein and fat instead of using glucose as fuel directly.11 It’s not very likely that the cost would be large enough to have any meaningful effect on your body weight in and of itself.
A recent review from the National Lipid Association (which is an organization seeking to enhance the knowledge and practice of lipid management in clinical medicine, not an industry organization for cooking oils, as the name might imply), confirms that diets with a very low carbohydrate content can help regulate appetite. It also concludes that there isn’t any evidence that low-carb and ketogenic diets are any better for losing weight than any other methods.12
In summary, both low-carbohydrate diets in general and ketogenic diet specifically can promote weight loss. That being said, there is no scientific evidence that they are superior compared to a mixed diet providing the same amount of calories. Ketogenic diets can help control hunger, suppress appetite, and regulate the amount of food you eat without you having to count calories in detail.
Ketogenic Diets and Performance
Time for some advanced stuff. You can skip the next 4 sections, if you are only here for the bacon and the bench press. They don’t contain anything you will be quizzed on in real life, but will give you an overview of the biochemistry behind exercise and performance in a ketogenic state.
During aerobic activity, like continuous cardiovascular exercise, your muscles require fuel to be able to work and contract with a certain intensity. Your liver and adipose tissue provide most of this fuel. The liver keeps your blood glucose levels elevated through a process called glycogenolysis. Glycogenolysis is the breakdown of glycogen into glucose, which is then released into the blood. Your liver can also produce ketone bodies from fatty acids in the blood. Plasma fatty acid levels are maintained through lipolysis, which release them from adipose tissue into the blood. This release is activated by so-called beta-adrenergic stimulation.
What does this mean? It means that you have 3 substrates for your heart and muscles to use as fuel during aerobic exercise: blood glucose, ketone bodies, and fatty acids. When you exercise with low to moderate intensity, a lot of the energy you expend will come from oxidation of fatty acids. That’s where ketone bodies could be valuable as an alternative fuel and help improve performance.
Carbohydrate is the best fuel for high-intensity exercise, but at a moderate intensity, fatty acid availability is the limiting factor. You have an almost unlimited supply of fatty acids in the form of your body fat, while your supplies of carbohydrate in the form of muscle- and liver glycogen are quite limited and won’t last longer than a few hours. A ketogenic diet could help increase reliance on fat instead of carbohydrates as fuel. Aat the same time, ketone bodies in the blood might help fuel prolonged workouts as an alternative fuel.
Anaerobic exercise is high-intensity exercise that doesn’t require oxygen, and that lasts a couple of minutes at most. We can only metabolize fat as energy for an exercise task with the help of oxygen, but we can metabolize carbs both with and without oxygen. During short, high-intensity tasks, a large portion of the energy used to perform them comes from creatine phosphate and lactate. The lactate comes from carbohydrates you have eaten earlier and stored in your muscles in the form of glycogen. Your ability to perform your best during high-intensity exercise depends on carbohydrate in the form of muscle glycogen. Research shows that a ketogenic diet might decrease this performance.13
How does all this work in real life? Let’s have a look at what the research has to tell us.
Endurance Training and Aerobic Exercise
When you cut carbs from your diet, your “burn” more fat. You don’t really burn fat, though. Fat is oxidized. That being said, your body becomes more reliant on fat oxidation during training when you’re on a ketogenic diet. When you eat a ketogenic diet, and give your body enough time to adapt to it, your fat oxidation during exercise can reach levels twice as high as that of someone eating a standard western diet.14 This is because of an increased capacity to use fatty acids as fuel.
A study from 2018 showed that cyclists, runners, and tri-athletes on a keto diet oxidized far more fat during training that usual.15 In that study, the keto group also lost significantly more fat, lost more weight, and even improved their performance a bit more after 12 weeks of training, compared to a control group.
Some studies and proponents claim that a ketogenic diet is superior for improving performance during endurance training. Available research does not support such claims.
There are a few studies showing minor improvements in performance and endurance, but they are the exceptions rather than the rule. For the most part, athletes on a keto diet seem to maintain their performance levels.16 1718 There are also studies where the subjects experienced performance decreases when cutting the carbs from their diets.19
One of the most common objections to studies examining the ketogenic diet and exercise performance is that they are too short. If a study only lasts a couple of weeks, maybe the potential benefits of keto adaptation won’t have materialized. Unfortunately, there aren’t a lot of long-term studies available to draw any conclusions from. One study with keto-adapted ultra-marathon runners and Ironman Triathlon competitors showed that their fat oxidation had more than doubled after 20 months.20 Unfortunately, the researchers didn’t measure performance markers. In any case, the athletes were elite athletes, placing very high both in national and international competitions, both before and after adapting a keto diet. This suggests that it is quite possible to perform at a high level in endurance events without relying on carbohydrates.
In a very recent study, runners followed a diet consisting of either 43% carbohydrate and 36% fat, or 4% carbohydrate and 78% fat during a month of training. Performance tests showed that their endurance capacity didn’t decrease when on a ketogenic diet, when exercise intensity was kept at a submaximal level. However, at a training intensity of 70% of Vo2Max or more, they couldn’t maintain their training efficiency. In addition, the keto-adapted athletes were at a higher risk of individual drops in endurance capacity.21
In summary, if you train mostly with a low to moderate intensity, you shouldn’t have any problems performing well on a ketogenic diet. However, there aren’t any scientific support for claims that a diet replacing carbs with fats will give you any advantages either. At higher training intensities, ketone bodies and body fat might not be powerful enough fuels to maintain the same performance levels as a carbohydrate-rich diet.
Resistance Training and Other Anaerobic Activities
There aren’t as many studies on the effects of ketogenic diets on strength training as endurance training. The available research suggests that, at least in the short term, you don’t have to worry about performance. On the other hand, a diet without carbohydrates might not be the best choice if your training goals involve muscular hypertrophy.
CrossFit athletes have been the focus of several keto-studies.
One study followed 12 non-elite CrossFit subjects, who either continued eating their normal diets or switched to a keto diet during 3 months of training. The subjects who eliminated carbs lost a lot more body fat, without any apparent decrease in running or strength performance. However, they lost muscle mass in their legs, and their vastus lateralis muscle thickness decreased. The subjects eating carbohydrates didn’t experience this loss of muscle mass.22
In another study, 27 male and female CrossFit participants ate an ad libitum diet consisting either of their usual food or max 50 grams of carbs a day for 6 weeks. During this time, the low-carbohydrate group lost significantly more body weight, along with several kilograms more body fat than the group eating their normal carbohydrate-rich diet. All subjects improved their exercise performance, without any significant differences between groups, and both groups did it without losing any muscle.23
When it comes to traditional strength training, a 2017 study looked at the effects of keto dieting on body composition, strength, and hormone levels. The subjects? Twenty-five resistance-trained men, who were put on either a standard western diet (20% of the energy from protein, 55% from carbohydrates, and 25% from fat) or a ketogenic diet. Both groups increased their fat free mass during 10 weeks of training, but the non-keto group gained significantly more. Both groups also lost body fat. In this case, the group eating a ketogenic diet were the ones who lost the most. All subjects increased their strength similarly regardless of diet, but the keto group also showed increased testosterone levels.24
One recent keto-study looked at powerlifters and Olympic weightlifters at different levels, from amateur to elite. During a 6 month long study, they either ate their usual diets, providing more than 250 grams of carbohydrates per day, or a ketogenic diet with less than 50 grams of carbohydrates per day. This was a crossover trial, where the subjects followed one diet for 3 months before switching to the other diet for the remaining months, in a randomized fashion. During the ketogenic phase, the lifters lost weight, more than half in the form of fat free mass. Despite this, there was no difference in performance depending on diet, and they could lift just as heavy regardless of carbohydrate intake.25
Finally, let’s take a look at a study featuring elite gymnasts from 2012. This was a small-scale study, with only 8 subjects. After a month almost completely devoid of carbohydrates, and with an energy intake below 2000 calories per day, the participants had lost both body weight and body fat. At the same time, they had managed to increase their fat free mass, although those gains were small enough to be non-significant. Three months later, the same gymnasts ate a standard western diet, providing around 50% carbohydrate, for the same amount of time. During this part of the study, their body composition didn’t change. Neither of the dietary interventions affected their strength or performance.26
In summary, most studies with strength-training subjects suggest that a ketogenic diet doesn’t impair performance the way you might expect from the way we know the energy systems of the body work. In general, there are no particular differences in strength and power when the subjects have more or less completely eliminated the carbohydrate content of their diets, compared to control.
On the other hard, a ketogenic diet might not be optimal for muscle growth. In the available studies, the subjects on the keto diets have gained less muscle, if they gained at all. Some studies show muscle loss only in the keto groups. Whether on not these losses are caused by the absence of carbohydrates or by the subjects spontaneously eating less is currently not known.
In any case, current research suggests that a ketogenic diet will work fine if you engage in strength training and want to lose body weight and body fat without losing strength. Keto doesn’t seem to offer any performance advantages, and might be a suboptimal choice if your goal is muscle hypertrophy.
If you strength train regularly, you probably know the importance of protein. Eat too little protein, and you could limit your potential for gaining muscle mass and strength.
A common concern is whether or not a high protein intake might prevent you from entering and remaining in ketosis. It’s a valid question. Your liver, and to some extent your kidneys, can convert protein to glucose during periods of starvation or when you strictly limit your carb intake through a process called gluconeogenesis. In addition, carbs aren’t the only thing in your diet with the potential to stimulate insulin release. Protein does, too, to varying degrees depending on the source. Proteins containing large amounts of the amino acid leucine, like whey protein, are more insulinogenic than sugar.
Fortunately, it’s not that easy to manipulate gluconeogenesis through dietary means. The conversion of protein to glucose does increase when you are in ketosis.27 Not by a lot, but it does increase, likely through a higher fatty acid availability and lower insulin levels. The glucose produced isn’t used as immediate fuel to any meaningful extent, but is stored as glycogen instead. That gives you several advantages.
First, it means that yes, you can actually store muscle glycogen even without dietary carbohydrate. Muscle glycogen synthesis improves post-exercise recovery. This means that you don’t have to give that up, even though you don’t eat carbs. The glycogen storage process sans carbs isn’t as efficient as if you had carb-loaded after a workout, but it doesn’t become non-existant either, like you might expect.
It also means that you can remain in ketosis despite a high protein intake. Since your muscles are using ketone bodies for energy, they don’t need glucose from gluconeogenesis as fuel to the same extent. That glucose ends up as muscle glycogen instead, and you remain in the ketogenic state.
How Much Protein Can You Eat and Still Be in Ketosis?
A standard ketogenic diet isn’t very rich in protein. That’s perfectly fine for the average person who doesn’t weight train for maximal muscle mass. If your goal is strength and hypertrophy, that type of ketogenic diet probably won’t cut it. So, how much protein can and should you eat?
Protein doesn’t have much of an effect on blood glucose.28 This means that you can eat a high-protein diet without having to worry about your blood sugar levels spiking and bringing you out of ketosis. The thing that might is the insulin response to what you eat. Fat is hardly insulinotropic at all, and you have already minimized your intake of carbohydrates. That leaves protein, which does cause insulin release.
How much protein can you eat before that release becomes too great for ketosis? That differs from person to person and is dependent on a number of factors. For one thing, there are genetic differences in how sensitive you are to insulin and how efficiently you use ketone bodies as fuel. In addition, your training status is a determining factor. The better shape you’re in, the more protein you can eat and still remain in ketosis. That’s one of the main reasons why you can eat more protein than an untrained individual, and more than standard recommendations for protein intake, during ketosis. Your body won’t need to release as much insulin to deal with the protein you eat and transport it to its intended destination and purpose.
The best way to make sure is to measure your blood ketone levels.That means that you will have to go out and buy a blood glucose meter that can also measure blood ketones. Such a device for consumer use isn’t very expensive at all.
When you have your blood glucose/ketone meter, start by restricting your carbohydrate intake enough to ensure that you should be in ketosis. If you limit your intake to 20 grams a day for a week, this should be quite low enough. During this time, eat as much protein as you are shooting for, say 1.6 to 2 grams per kilogram of body weight and day. This amount covers the protein needs for close to 99% of the population, including competitive bodybuilders.
Test your ketone levels using the blood glucose meter. If they are at 1 mmol/L or above, you don’t have to make any changes. If that is the case, you have already found the protein intake you can eat and remain in ketosis, as long as you keep your carb intake down. You can even experiment by increasing your protein intake even further from there, if your wish. If so, increase it in steps of 10 grams until you’re kicked from ketosis.
If your blood glucose meter shows ketone levels below 1 mmol/L, and you are sure that you haven’t been eating more carbohydrates than intended, you’ll have to take measures by lowering your protein intake a bit. Do as described above, but instead of increasing your protein intake, gradually lower it by 10 grams at a time until your blood ketone levels go above 1 mmol/L.
Once you have found the highest protein intake you can maintain and still remain in ketosis, you don’t need to check your ketone levels more than once a week or so from there on out. Just do it now and then to make sure you’re on track.
In summary, you don’t have to reduce your protein intake to levels corresponding to standard ketogenic recommendations. When you weight train, and if you have a larger than average amount of muscle, you have a number of advantages that make it possible for you to eat quite a lot of protein and still both reach and remain in ketosis. If you really want to make sure, and not leave anything to chance, you can use a blood glucose meter with the capability to measure ketones to do so.
Are ketogenic diets safe? Can you stay in ketosis long-term without health issues?
That’s where science fails to provide us with any sure-fire answers. Not because of any particular suspicions of harm, but because there isn’t any real long-term data available. We can say for certain that a short-term ketogenic diet is not harmful. If anything, shorter cycles of ketogenic dieting seem to be beneficial for the health of both brain and body.29
A 2004 study showed no negative effects of staying on a ketogenic diet for two years.30 Of course, two years is kind of a short-term study in this instance. For a diet to be considered safe, you have to be able to pretty much stay on it your entire life without negative consequences. Unfortunately, controlled studies longer than two years are nowhere to be seen, at least not yet.31 There is currently no scientific consensus. Some researchers and doctors advise against the ketogenic diet, arguing that we don’t know the long-term effects. On the other hand, other experts in the field recommend keto, based on short-term health benefits and the fact that carbohydrate is not a physiological necessity.
Both sides have their proponents, but as of yet, neither side can guarantee long-term safety or show any concrete evidence of harmful effects. We do know that millions have used the ketogenic diet for years and years. So far, there are no convincing evidence that their health has suffered for it.
Documented negative side-effects of a ketogenic diet include kidney stones and deficiency of certain vitamins and minerals. The latter is probably caused more by a poor or uneducated choice of foods rather than by ketosis itself.
When you start off on the ketogenic diet, you most likely will experience a number of negative effects. These aren’t harmful, but they can be quite unpleasant to deal with. Unpleasant enough that many discard the diet before they have adapted to it. Some of the side effects that you can pretty much count on experiencing include fatigue, dizziness, nausea, decreased physical and mental performance, trouble concentrating, and trouble falling and staying asleep. In addition, vomiting, constipation, and headaches have been reported. These effects will pass after a few days to weeks, when your brain and body have adapted to using ketones instead of glucose.
If you switch from an omnivorous diet to a more restrictive ketogenic diet, the greatest risk is probably nutritional deficiencies. Not macronutrients like fat and protein but vitamins and minerals. In general, animal foods are just as nutrient-dense or denser than vegetable foods, but if you just switch over without doing proper research, you might end up with an imbalanced diet. A ketogenic diet doesn’t have to be nutritionally poor, but you need to read up on how to base it on diverse enough food to cover all bases. In general, it is a more restrictive diet than most.
A diet with a poor fatty acid balance, too much salt, and various additives like sodium nitrite could have health consequences. On a ketogenic diet, your intake of these things could increase quite a lot, depending on what you eat. Most likely, the majority of the potential health consequences of a ketogenic diet are caused by a poor choice of foods rather than any negative effects of ketosis per se.
In summary, eating a ketogenic diet can result in a number of documented short-term side-effects. These are transitory and benign, if unpleasant, and pass within a week or two. Whether or not a long-term ketogenic diet can impact your health is unclear, but nothing in particular suggests that this is the case.
So, what should you base your diet on? What should you eat? This part of the article will provide you with a few concrete tips on how to compose your ketogenic meals. You won’t find any detailed measurements in grams here. Instead, you will have to adjust your meal sizes and their energy content on your own, based on your own requirements. A ketogenic diet is nothing special in that regard. You still need an energy surplus to gain weight, and an energy deficit to lose weight.
You don’t have to base your diet on bacon and eggs just because you’re doing keto. Of course, everything’s better with bacon, but it is not something you should base your diet around.
Here are a few examples of complete meal suggestions that can be a part of a healthy ketogenic diet. Meals that are both rich in nutrients and hopefully sound appetizing.
- Mackerel in tomato sauce with scrambled eggs, a green salad, and fresh tomatoes
- Ground beef patties with onions and gravy, and oven-baked root vegetables
- Cauliflower pizza with mozzarella cheese and bacon
- Oven-baked salmon with parmesan cheese and cream, on a bed of spinach
- Meatloaf made with cream and eggs + brown gravy + green string beans
- Chicken thigh casserole with creamy sauce and mixed greens
Make sure to have these foods and ingredients in the fridge, freezer, or pantry, and you will never find yourself empty-handed when it’s time to whip up a meal.
- Fish and seafood. Both canned goods like tuna, mackerel, and sardines, and fresh or frozen fish like salmon are healthy and muscle-building food. Of course, you can eat lean fish, but then you’ll need another source of fat as well.
- Meat, including both red and white meat. Beef, pork, lamb, game, chicken, turkey, and so on. Don’t be afraid of the fattier cuts. On the contrary, these are often the better choice for a ketogenic diet, and often the tastiest and cheapest, too.
- Low-carb vegetables, fruits, and other plants. Fibrous vegetables without too much starch can and should be part of your diet. Broccoli and cauliflower are low-carb enough that you can include them as part of a ketogenic diet, in moderate amounts. Spinach, arugula, asparagus, cabbage, cucumbers, tomatoes, kale, and bell peppers can be used without any particular restrictions. Try to pick a wide variety of colors. Differently colored vegetables contain different micronutrients and antioxidants. Avocado and olives are two fatty fruits that are popular amongst keto-fans for a good reason.
- Nuts and seeds. All kinds of nuts, seeds, and almonds are a great addition to a keto diet. They are low in carbs and high in fat and protein. The fat is of varying quality depending on the nut, and the protein doesn’t have the best amino acid composition, but as a part of your diet as a whole, they are valuable and provide both energy and nutrients.
- Eggs. The most complete single food there is. Perfect both as a main dish and in cooking.
- Dairy products. If you aren’t intolerant to dairy, milk products give you access to the most muscle-building proteins of all. Full-fat dairy products are associated with cardiometabolic health.32 Milk, cottage cheese, curd, quark, hard and soft cheeses, yoghurt, and butter are rich in either protein or fat, or both, and in most cases also provide plenty of calcium.
- Fats. Olive oil, rapeseed oil, nutty oil, avocado oil, coconut oil, and good old butter are pure fat sources suitable both for cooking and for adding to any recipe to increase the fat content.
If there is one thing you probably shouldn’t over-indulge in, it’s processed meat. Bacon, kassler, sausages, and various packaged lunch meats. Not because they are nutritionally worthless, but because they are associated with colorectal cancer. The World Cancer Research Fund considers processed meats to be carcinogenic in humans, not only through epidemiology. Several mechanisms could be responsible, but heme iron and sodium nitrite used as a preservative and coloring agent are the most probable. Sodium nitrite is classified as “probably carcinogenic to humans” by The International Agency for Research on Cancer. It might be a good idea to not rely too heavily on processed meats.
Let’s take a moment and summarize the effects of a ketogenic diet on body weight, fat loss, performance, strength, and hypertrophy. What’s the verdict?
Keto works fine if you want to lose body weight and body fat. Your energy balance is still the deciding factor, but a ketogenic diet can provide certain advantages when it comes to appetite regulation. This could make it easier to ensure an energy deficit without having to count calories. A ketogenic diet might also increase your energy expenditure a bit, but probably not enough to have any meaningful impact on your body weight.
Current research suggests that a ketogenic diet won’t impair performance during low to moderate intensity endurance training. You can even improve your aerobic ability without carbohydrates. Higher intensities is where you might run into trouble. When exercising at a high intensity, fat and ketone bodies might not be good enough, possibly limiting performance somewhat.
What about strength training and other anaerobic forms of exercise? No real long-term studies support keto here, but at least in the short term, you probably won’t have to worry about performing worse than usual. You can both maintain and improve muscular strength and power with a ketogenic diet, both as an average gym member and as a high-level weight lifter or powerlifter.
The one thing that might suffer is muscle growth. A number of the available studies show that eliminating carbs might restrict muscle growth or even lead to muscle loss. It could simply be that a ketogenic diet caused the subjects to eat less, and that this is why muscle growth was reduced compared to those eating carbohydrates. In either case, this is something to keep in mind. It is possible that a carbohydrate-restrictive diet isn’t as good as a high-carb diet for building muscle mass.
Finally, is the ketogenic diet safe? We don’t need carbs to live and function. They can certainly be useful, but we have other systems in place if we eliminate them for some reason. When you first restrict or cut out dietary carbohydrate, you shouldn’t expect to feel tip-top. Nausea, dizziness, fatigue, and other unpleasant things are common the first days to weeks. Fortunately, these side effects pass when your brain and your body learn to use ketones properly. There are no long-term studies that guarantee the safety of the ketogenic study, but neither is there anything in particular indicating any dangers. As long as you choose healthy foods that cover your micronutrient requirements, you don’t have to put a time limit on your diet.
A ketogenic diet is a viable alternative to traditional high-carbohydrate diets for active individuals and strength athletes. If you want to experiment with a more or less carb-free diet, there are few reasons to discourage you from doing so.
That’s it! You’ve reached the end of our guide to the ketogenic diet!
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- Int J Environ Res Public Health. 2014 Feb 19;11(2):2092-107. Ketogenic diet for obesity: friend or foe?
- Prostaglandins Leukot Essent Fatty Acids. 2004 Mar;70(3):309-19. The therapeutic implications of ketone bodies: the effects of ketone bodies in pathological conditions: ketosis, ketogenic diet, redox states, insulin resistance, and mitochondrial metabolism.
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