TABLE OF CONTENTSWHAT IS THE KETOGENIC DIET?USE OF ENERGY SUBSTRATESWHAT ARE KETONIC BODIES?BENEFITS OF KETOSISPROBLEMS WITH THE KETOGENIC DIETCONCLUSIONS
WHAT IS THE KETOGENIC DIET?
The ketogenic diet is a type of diet in which carbohydrates are significantly restricted in order to stop glucose from being the main energy substrate and move on to fats and ketone bodies. That is, entering a state called ketosis. For most people reducing carbohydrates to less than 100 grams per day will be enough to get into ketosis, however many ketogenic diet purists recommend cutting them down to 50 grams daily.
A couple of things need to be made clear:
- The ketogenic diet is not a high-fat, high-protein, low-carb diet. It is a diet low in carbohydrates, high in fat and MODERATE in protein.
- Many people are afraid of the ketogenic diet because they confuse ketosis with ketoacidosis. In fact, even google confuses it. If you search for "ketosis" you get the following as the recommended search:
The reality is that ketosis is a metabolic state that the body is adapted to being, while ketoacidosis is a state in which excess ketone bodies creates systemic acidity that is very dangerous to health. But that happens when there is no insulin (in diabetics for example) so it is not something that happens in healthy people. Therefore, it is important to differentiate ketosis from ketoacidosis.
In normal people in ketosis, the production of ketone bodies can be between 120-180 grams / day and the concentration of ketones 4-10 nmol / dL, while in ketoacidosis we have a production of more than 400 grams of ketone bodies per day, at a concentration of more than 20 nmol / dL.
USE OF ENERGY SUBSTRATES
The body is able to use 4 substrates to obtain energy. Glucose, fatty acids, amino acids and ketone bodies.
And these are stored in different amounts in the body, being the fatty acids those that are stored in greater quantity, mainly in the adipose tissue. Keep in mind that a person with 20% body fat can accumulate more than 150,000 kcal in the form of triglycerides.
Next we would have amino acids and glucose. The latter is stored in the liver and muscles in the form of glycogen. The liver can store about 100-150 grams and in the muscle it will depend on the amount of muscle mass that you have, but between 500-800 grams is normal.
At rest the body tends to use a mixture of fatty acids and glucose for energy, although fatty acids are predominantly used. However, the more intensity there is in the activity we are doing, the greater percentage of that energy will come from hydrates and less from fatty acids, as we can see in the following graph:
The body, under special circumstances, can also transform amino acids or glycerol from triglycerides into glucose in the liver through gluconeogenesis to obtain energy, although it is not a route that it usually uses unless it is very low in energy and glucose. So we will not say that it is a priority metabolic pathway under normal conditions. We have to understand that the body will use the most abundant energy substrate as a priority. If the body has enough glucose, it will use this as its main substrate, while if it is scarce it will change and use fatty acids as its main energy source.
And now let's talk about ketone bodies. Although there are many tissues and organs that work with glucose and fatty acids, there are others that cannot use fatty acids for energy. The main one, the brain. The fact that the brain cannot use fatty acids has led to the belief that it can only use glucose, hence the myth that the brain needs sugar to function.
Clearly a misconception, because sugar is a disaccharide made up of a fructose molecule and a glucose molecule, and the brain, if it needs anything, is glucose. So the brain does not need sugar. And also, the brain can use ketone bodies as an energy substrate when glucose is low.
WHAT ARE KETONIC BODIES?
Ketone bodies are compounds that are produced mainly in the mitochondrial matrix of the mitochondria of the liver (and of the kidney to a lesser extent) and are derived from fatty acids, although they can also be obtained from certain amino acids but in very minimal amounts.
We mainly have 3 ketone bodies:
- Acetoacetic acid or acetoacetate
- Betahydroxybutyric acid or Ī²-hydroxybutyrate
- Acetone
These compounds will serve to obtain energy mainly for the brain, which under conditions of glucose shortage can use ketone bodies to cover up to 75% of its energy requirements.
BENEFITS OF KETOSIS
There are many potential benefits to going through periods of ketosis, but we will detail the most important ones and the ones for which there is more evidence.
WEIGHTLOSS
This is a debatable benefit and it has several nuances. Many people have decided to go on a very low carbohydrate diet as they have fallen into the myth that carbohydrates are fattening and that it is impossible to lose body fat by following a high carbohydrate diet. As I have already said, this is a myth, which I have already disproved in many other entries on this blog that I recommend that you read so that you get rid of fears and misinformation.
However, while carbs aren't Public Enemy No. 1, there is some merit to a ketogenic diet for weight loss. Mainly for 3 reasons.
REASON 1
The first reason is that a ketogenic diet is generally higher in protein than a diet based on foods rich in carbohydrates. This is one of the main reasons why short and medium-term studies have shown that a diet high in fat and low in carbohydrates tends to have better results when it comes to losing fat, because proteins increase in these groups ( 1 , 2 , 3 , 4 , 5 , 6 ). However, when balancing amounts of protein and calories these advantages generally disappear ( 1 , 2 , 3 , 4 , 5 , 6 ).
Let's take a clear example of the issue that I am trying to explain: In the following study , 4 groups were observed that had different dietary approaches. All 4 were on a diet with a 33% caloric deficit and all participants (n = 132) had a BMI of approximately 37. They were all overweight.
- GROUP 1 : Normal proteins / normal CH
- GROUP 2 : Normal proteins / low CH
- GROUP 3 : High proteins / normal CH
- GROUP 4 : High protein / low CH
RESULTS : At 3 and 12 months, weight loss was greater in the groups with high protein, regardless of the amount of CH that they accompanied.
In addition, all health markers improved equally in the 4 groups, except for diastolic pressure, which improved more in the high protein, high CH group.
What this study lets us see is what has been suspected for some time. What is really important in terms of weight loss is the caloric deficit and the protein ratio mainly. The key macronutrient is protein, not CH. Therefore, increasing protein in a phase of definition or weight loss seems to be the best strategy, whatever diet you follow.
Speaking of ketogenic diets, in 2016 Hall et al. conducted a study comparing a ketogenic diet with an isocaloric diet that was higher in carbohydrates in obese people and were able to observe that not only was there no greater loss of fat in the ketogenic diet, but there was also a small advantage over the other diet.
Regarding protein: How much should be consumed in a definition period? Here you have the answer.
REASON 2
Improve short-term results. That is, another reason why the ketogenic diet is so popular is because in the short term those who follow it lose a very significant amount of weight. I repeat, they lose a significant amount of WEIGHT.
And it is that when glycogen stores are depleted it is very easy to lose weight since glycogen carries a lot of water (each gram of it can drag 3-4 grams of water), so it is not uncommon to lose 2-3 kg of weight in the first few days of following a ketogenic diet. This is good and bad.
That is, it is good as it can increase the initial motivation to follow the plan. It is bad in the sense that many people believe that this is fat and then as the weight loss stabilizes they can be discouraged by not keeping up with that rate. The reality is that this happens when people have unrealistic expectations when it comes to fat loss. At the end of the day, and what was observed in this 2017 study , is that the best diet is the one that creates greater adherence to the individual.
And let's not forget that a ketogenic diet is a restrictive diet in and of itself, so it's fair to say that the more restrictive a diet is, the less adherence it has overall. You have to consider this.
REASON 3
Ketogenic diets seem to have their greatest strength in your satiety.
A systematic review from 2015 appears to reach those conclusions. Ketone bodies seem to dramatically increase satiety in many cases (let's not forget that you have to individualize, I have had cases of people who were doing a ketogenic diet and gained weight) so it can be a very useful tool for certain phases or periods.
LIPIDIC PROFILE
There is a lot of evidence that a well thought out ketogenic diet improves many health parameters.
For example, in 2013 a meta-analysis came out that concluded that a ketogenic diet improved triglycerides, blood pressure, and HDL than a high-carbohydrate diet for obese people. It must also be said that LDL increased, however the increase in LDL is total, while the particle size increased and the total LDL was divided into fewer particles of larger size each (or what is the same, LDL-P decreased) so the cardiovascular risk was reduced. If you want to know more about total LDL and LDL-P you have the following article .
We also have another study from 2003 that looked at the effect of a ketogenic diet in 83 obese patients for 24 weeks. The results were quite good, as total cholesterol was lowered, HDL increased, LDL lowered, triglycerides lowered, and glucose level lowered.
However, a very important factor must be taken into account. These studies are done in obese people who have lost weight. This fact by itself will already make all these parameters drastically improve. Obesity is directly related to an increase in cardiovascular risk, and that these parameters are altered. Therefore, while it is a valid tool, simply losing weight and losing body fat using the protocol that creates the most adherence is likely to have similar benefits. We can debate whether more or less, but the priority is to reduce the% fat as effectively as possible, which may or may not be a ketogenic diet.
NEURODEGENERATIVE DISEASES
There is a growing line of research that observes that the ketogenic diet is more than effective in treating epileptic problems, and there are more than enough studies that demonstrate its effectiveness .
In the second link, which is a review, they also come to the conclusion that I told you before, that the ketogenic diet (especially in children) is difficult to follow and that the drops in studies are largely due to the dislike of the diet and gastrointestinal problems thereof, which must be taken into account when proposing a nutritional protocol of these characteristics.
There also appears to be an interesting benefit of the ketogenic diet in neurodegenerative diseases such as Azlheimer or Parkinson's .
METABOLIC FLEXIBILITY
One of the great benefits of the diet is that it increases our metabolic flexibility.
What is metabolic flexibility? Well, explained in the simplest way possible is the body's ability to change its energy substrate in the most optimal way in order to obtain energy.
That is, before we have talked about that depending on the intensity of the exercise the body will need more energy that comes from carbohydrates. The problem is that many people due to their lifestyle, diet excessively high in carbohydrates, sugar and refined flours, sedentary lifestyle, high body fat, etc ... have zero metabolic flexibility, so their metabolism is excessively dependent on glucose. That is, they need glucose significantly from very low intensities. Even athletes of moderate intensity also have this problem, that they are very dependent on glucose.
We have also seen before that the body has a very limited amount of energy stored in the form of glycogen, and yet it has a lot of energy stored in adipose tissue. However, these people cannot access that energy because they depend so much on glucose that they need to continually replenish that small energy tank.
On the other hand, what a person with good metabolic flexibility will do is raise the aerobic threshold, or intensity threshold in which the body needs glucose for energy as a priority, so that it will have a "glycogen sparing" metabolism for Put it in some way, and you will focus on getting your energy primarily from fat stores. That is what they are for, by the way. That is, we have tens of thousands of calories stored that should serve to give us energy and we are all the time depending on glycogen for everything. It doesn't make much sense evolutionarily speaking.
That is, in efforts or intensities that previously used almost only glucose to obtain energy, with a good metabolic flexibility they will now use much more% of fat to obtain it, saving the glycogen that we remember that can objectively give less energy, and that therefore it makes all the sense in the world to save it for when it is really needed. It has been seen that it is possible to go from burning 95% carbohydrates and 5% fat to 60% of VO2 max to spending, at the same intensity, 22% glycogen and 78% fat. Imagine the difference.
PROBLEMS WITH THE KETOGENIC DIET
SPORTS PERFORMANCE
Here we will include both muscle mass gain and sports performance.
Regarding the gain of muscle mass, we find several problems. The first is that it is well established that the optimal gain in muscle mass is found with diets that have a medium percentage of carbohydrates, apart from being high in protein, obviously. At least 3 grams / kg of carbohydrates are generally required to maximize muscle mass gain and to be able to train at high intensities.
Remember what we have said before, the greater the intensity of the exercise, the greater the body's need to use carbohydrates for energy. Therefore, it makes sense that if we are focused on gaining muscle mass and doing high intensity workouts, carbohydrates are an important requirement to maximize results. However, that should not lead us to believe that to gain muscle mass we must consume 60% carbohydrates or we are doing things wrong (as many people believe). In this article I already explained the real carbohydrate needs in terms of gaining muscle mass. They are not as high as many believe, but they are necessary.
It is also interesting to mention that a diet that is too low in carbohydrates will reduce T3 levels, which will reduce protein synthesis. And there are also other potential negative effects why an excessively low carbohydrate diet is not the best for gaining muscle mass:
- The cortisol / testosterone ratio varies. That means there is more cortisol and less testosterone . Went just the opposite.
- Protein degradation increases and synthesis decreases.
- Exercise intensity decreases with low CH
- Low glycogen levels interfere with muscle growth
Finally, and regarding the gain of muscle mass, we must remember as we have seen previously that a ketogenic diet is generally very satiating, so it can be difficult to consume all the necessary calories if we are following a protocol that leaves us extremely satiated.
Regarding sports performance we have an extensive review that observes the following:
With studies at an intensity of 60-80% of VO2 it was shown that low-carb diets did not give any benefit in performance or a decrease in it after the period of adaptation to low CH. When the performance was measured at high intensities (+ 80% VO2), the best that could be maintained with respect to high CH. But in most cases it decreased. In most cases, glycogen storage was diminished, which would explain why sports performance is diminished.
However, this review is from the year 2000 and since then it has rained a lot, and several studies have observed that contrary to what may be believed, in some cases sports performance can improve or at least not be impaired , probably due to flexibility metabolic rate that we have discussed before.
ADAPTATION
One of the main problems when starting a ketogenic diet is adaptation. Remember that we are, so to speak, changing the metabolism and this has very marked effects on many people. The body requires time to start producing the changes that will allow us to use mainly fats and ketone bodies, and in this period is when certain side effects can appear.
The main ones are:
- Tiredness and little ability to generate intensity in training
- Bad breath
- Headaches and headaches
- Reduced pumping when training with high repetitions
These effects do not always appear (I, for example, do not experience them) and their duration is variable. There are people who take a week to adapt and others can suffer 3-4 weeks. However, it is always temporary.
GREASE BURNING MACHINE
This more than a problem is an error of interpretation.
Many people believe (and many people say this as a positive effect) that by going on a ketogenic diet they will become a fat burning machine. As if that means that they are going to lose body fat at a forceful marches. This is a misconception, because they are two different things.
Yes, it is true that you are going to become a fat burning machine in the sense that your body will prioritize the use of fat as fuel over glucose. That does not mean that you are going to lose body fat, since the fat that you are burning for fuel mainly comes from the fat that you are consuming. That is, it increases fat burning because it increases its consumption. Yes, it is true that you will lose body fat if you are in a caloric deficit and the ketogenic diet, as we have talked about previously, is satiating, high in protein and is a valid tool to enter that caloric deficit, but do not be fooled by these people who It tells you that you will become fat burning machines by being in ketosis, because if that is not accompanied by a caloric deficit ... it is useless.
ADHERENCE
Finally, I would like to talk about adherence to this type of diet. Let's face it, the ketogenic diet is, by definition, an exclusion diet. I don't think there is much debate about it. It may have its advantages, its disadvantages and its uses, but the reality is that you are excluding an important group of nutrients and that greatly affects adherence. Remember that adherence is essential to achieve results and the most optimal protocol at a theoretical level can become a disastrous protocol at a practical level if you are not able to follow. Hence, in the article on clear priorities, I make it very clear that anything that greatly compromises adherence should be taken as a red flag.
This is not unique to the ketogenic diet. Any excessively restrictive diet has the same problem. The vegan diet, for example, is another diet that, while perfectly viable and healthy, is also a diet that has a high abandonment rate. Precisely because it is a very restrictive diet.
Studies that show that the ketogenic diet is superior to a more varied diet always have several common problems:
- They are short term. They usually last 6 months, which at the level of adherence does not help me at all. It's okay to follow a protocol for 6 months, but I want to know if you are able to follow it for years. This is how I value adherence, and in the long term the ketogenic diet has a high abandonment rate, which would indicate that its most appropriate use is as a one-off or periodic tool.
- They do not take novelty into account. As these are short-term studies, adherence is often increased simply by doing a different protocol. These studies usually compare "standard" diets or what the patient was following versus the novel diet (in this case, the ketogenic). This means that in the initial stages you usually see some improvement, which eventually fades.
- Calories and macronutrients are not balanced. Ketogenic diets tend to be, as I explained above, higher in protein and more satiating, generating more caloric deficits, which is why they tend to increase the results compared to other diets with less protein or higher in calories. Seeing better results tends to motivate, although these results are not equivalent as they are not in the same conditions.
Simply note that, by common sense, an exclusion diet will always have more problems in the long run than one that allows more options. Following a well planned ketogenic diet is a viable option, but if you find that you cannot follow it and that you are failing it, looking for an alternative would be ideal.
CONCLUSIONS
I hope this article has solved the biggest doubts you have about the ketogenic diet and that it has guided you. It is clear that there are many issues that I have not covered regarding it, such as how to structure a good ketogenic diet, mistakes that are made often, what types of ketogenic diet are there and how to implement them in a planning ...
But this will be for another time, I think there is already too much information in the same article.
We have 40 grams of fat that give a total of 360 kcal (almost half of the entire hamburger) while we have 62 grams of carbohydrates, or what is equivalent to 248 kcal. Let's not forget that fat is also extremely palatable, that it has more than twice the calories of carbohydrates and that it is very easy to reach a caloric surplus with a diet very high in fat if they are from ultra-processed products. So in my opinion, if you are going to restrict something, it should be fat mainly that day.
