Ketogenic diet and weight loss.
In 2018, about one in four persons on earth was overweight or obese. This makes obesity a dramatic epidemic in many countries. Whether an individual has extra kilos is determined by the Body Mass Index (BMI), which is calculated by dividing the body weight by the square meter of the height. When BMI equals or exceeds 25 we talk about overweight and when it is equal or higher than 30 we talk about obesity. In all cases, the process is the same and is due to an unbalanced diet that leads to the storage of fat in the body.
Overweight and obesity are not dangerous themselves, but they are risk factors for other diseases like cardiovascular diseases. They can worsen some conditions such as diabetes as well.
The good news is that they are reversible and preventable. Indeed, weight loss strategies with proven efficacy include sport activity, decreasing fat intake and surgery in extreme cases. An increasing evidence suggests that a ketogenic diet is effective for weight loss too.
What is a ketogenic diet?
Ketogenic diet or keto diet has one main principle that is a very low carbohydrate intake and a high fat intake. In simplified terms, this means favouring oily fish such as salmon, unprocessed cheese, butter, nuts and seeds, unsaturated fat containing oils like olive oil and coconut oil, avocado and low-carbohydrate vegetables, including tomatoes, onions, paprika, and zucchini for instance, against high carbohydrate food such as root vegetables, grains, fruits and processed sweet products like fruit-juice, candies and ice-cream. Some high protein food like beans and legumes are to be avoided as well.
Alternating carbohydrates with fat will make the metabolic shift to a mechanism called ketosis. Ketosis occurs naturally in the body, during a night of sleeping, pregnancy and intense physical activity for example. However, it is exacerbated on a keto diet. Ketosis starts when all the glucose available in the body to produce energy is consumed. At this stage, the stored fat is released and metabolised into ketones, also called ketone bodies, to produce the energy our organism needs to function. This is what is generally known as “burning the excess of fat” and the release of ketones in the blood gives its name to ketosis. If the diet was protein-rich, the body would have used the protein’s amino-acids to turn them into glucose. This would have decreased the amount of fat burned.
In contrast with the pathological diabetes ketoacidosis that can lead to coma, the nutritional or physiological ketosis induced by the ketogenic diet is known to be moderate as the blood ketone levels are relatively not that high. In fact, they are just enough to be actively used by the brain instead of glucose. In addition, there is no successive acidification of the blood that used to occur in diabetes. Therefore, the ketogenic diet has a relatively safer metabolic process.
Types of ketogenic diets
Although sharing the same basis of low carbohydrates and high fat, different types of ketogenic diets exist, and they are slightly different comparing to each other. The proportion of carbohydrates, fat and proteins could be at the origin of this difference, but also the nature of these nutrients and the type of food involved.
1. The Standard Ketogenic Diet
Also known as the very-low-carbohydrate keto diet, it is the standard version of the diet. It is mostly followed for weight loss and some specific therapies. It includes:
- 20-50g of carbohydrate (5-10%);
- 40-60g of protein (20%);
- 70 to 75% for fat, depending on the individual capacity.
2. The Well-Formulated Ketogenic Diet
In this case, the balance between fat, protein, and carbohydrates is optimal for ketosis to happen.
3. The Medium Chain Triglycerides (MCT) Ketogenic Diet
This formulation implies that most of the fat portion is made of MCTs that tend to be more metabolised into ketones than long-chain triglycerides. Coconut oil is a good source of this type of triglycerides. That said, high consumption of MCTs may have side effects such as digestive symptoms including diarrhoea. In addition, their effect on weight loss is understudied.
4. The Targeted Ketogenic Diet
This type of diet has the characteristic to take the carbohydrate daily portion (25-50 grams) at a “targeted” time, which is specifically before or after physical activity by 30 minutes to one hour.
5. The Cyclical Ketogenic Diet
This variant follows a cycle for carbohydrate intake. It starts with several days (e.g. 5 days) of low-carbohydrate intake (the usual 20-50g of the standard ketogenic diet) followed by 1 to 2 days of high carbohydrate intake or what is known as “carb-loading”, where 450-600 grams of carbohydrates are consumed. This diet is suitable for people practicing an intense physical activity such as bodybuilders and athletes. It favours reducing the fat body mass while maximizing the muscle body mass.
6. The high protein ketogenic diet
This alternative formula is similar to the standard version of the ketogenic diet, except that the protein intake is about 10% higher in the detriment of fat intake. It is suitable for people with high protein needs.
How does the process work?
The most common explanation of weight loss induced by the keto diet is that in the absence of carbohydrates, the body mobilises fat, including the excess stored, as a source of calories to the body. Other explanations are currently discussed by scientists. One is that the metabolism of the dietary proteins takes a lot of calories, which leads to the use of the body fat to cover the needs, which in its turn leads to weight loss. Another hypothesis is that the consumption of the proteins in the diet leads to feeling satiated and a loss of appetite which induces a weight reduction. Yet another explanation suggests that anorexia is induced by ketones themselves when used by the brain.
Benefits of the keto diet associated with weight loss
1. Weight loss
Efficacy. There is a strong body of evidence suggesting that the ketogenic diet is a good alternative for weight loss compared with conventional low-fat diet. Its efficacy is also proven in the long run to some extent.
Hunger control. Why is the keto diet efficient for weight loss is most probably linked to a couple of other benefits such as hunger control. As one research showed, the keto diet followers tend to feel less the need to eat.
Hormonal regulation. Another benefit conducting to weight loss is the power of the ketogenic diet to regulate hormones promoting or demoting appetite. For example, it reduces ghrelin blood levels affecting appetite that decreases accordingly. It decreases insulin, which reduces the risk of developing insulin resistance in obese people. They consequently avoid being constantly hungry.
2. Performance and mood
Thanks to the shift from sugar use to fat use, the body on a keto diet is constantly having the necessary energy from ketones, which seem to increase both the physical and cognitive performance. This is sustained over time as body fat reserves could provide enough energy for weeks or months in contrast with sugar.
Furthermore, bad mood and cognitive impairment tend to be frequent in overweight and today, there is a scientific evidence showing that ketones improve the mood and address cognitive impairment induced by weight gain.
3. Effect on disease risk factors
In a study showing the long-term efficacy of the ketogenic diet on obese participants for a 24-week period, the researchers found out that bad cholesterol decreased while good cholesterol increased after the diet. They reported that glucose also decreased. This shows that the diet has the potential to protect against cardiovascular risk and diabetes.
4. Type 2 diabetes management
The ketogenic diet seems to be adapted for type 2 diabetes management and treatment with lower side effects as compared with medication. It allows a better glycaemic control due to the low carbohydrate intake, and in the long run, it leads to a better diabetes control as HBA1C, a biomarker of diabetes complications, decreases. The research argues that high protein keto diet is even more beneficial for weight loss, body mass composition, and cardiovascular risk. In addition, other researchers reported that diabetes patients on a low-carbohydrate diet could even eliminate medication or take a lower dose of insulin.
The keto diet safety risk is often associated with the potential ketoacidosis, the blood fat level, and the kidney function. As described above, the ketoacidosis should not happen unless there is a potentiality for it (e.g. Diabetes and pregnancy), in which case a medical surveillance is needed. With regards to the blood levels of fat, many studies reported that on keto diet, bad fat decreases and good fat increases. Indeed, total cholesterol and triglyceride levels decrease while High-Density Lipoprotein (HDL) representing the good portion of cholesterol increases. In addition, Low-Density Lipoprotein (LDL) part of the bad portion of cholesterol is reduced in size and volume. The kidney function should stay stable as well in most of the cases.
The ketosis signs. Although many signs count among the benefits of a keto diet, there are some which may be unpleasant. In fact, ketones are very volatile compounds that could lead to a bad breath smell. They are partly eliminated through sweat giving it a specific and potentially unwanted odour.
Digestive side effects. The most common digestive symptom is constipation, but diarrhoea can occur as well.
The keto flu. Occurs the first week of starting the keto diet, depending on the individual’s response. The symptoms are temporary and include headaches, fatigue, irritable mood, difficulty to concentrate, demotivation, dizziness, nausea, muscle cramps, heart palpitations among others. These symptoms are due to the body adaptation to using fat instead of carbohydrates as a main source of energy, which in the beginning leads to water and sodium loss in the urines, causing a dehydration responsible of the keto flu symptoms. After this “hard time” more energy can be expected.
Ketoacidosis. Recognizable by a series of symptoms that include confusion and tiredness, digestive signs such as pain and vomiting, dryness and thirst, and fast breathing.
Long-term side effects. May include kidney stones and osteoporosis, and nutritional deprivation.
Tips for effective and safe weight loss on a ketogenic diet
If you have diabetes, high blood pressure, abnormal kidney function, or you are pregnant or breastfeeding, the keto diet might be unsafe for you. Better to seek the advice of your treating physician and/or a nutritionist.
If you suffer from the keto flu, you can take salt and water to relieve the symptoms. If it does not work, try to temporarily increase your fat intake in such a way that you feel satiated. This will help boost your mood and give you more energy. You can alternatively lower your carbohydrate intake gradually.
Planning your meals is a good way to organize your shopping and make sure that you reach your dietary goals.
Do not neglect fibres in your diet. This will ease the digestion and make your diet balanced.
In the beginning of the diet, you can start slowly to help your body adapt. For instance, you can gradually decrease the carbohydrate portion until it meets the dietary requirements and you can start with a low-intensity to moderate-intensity physical activity and increase it over time so that you avoid additional stress to your body. Same goes with stress due to hunger or eating too much in the beginning of the diet. If you feel hungry, eat what is recommended in the diet and do not blame yourself about the quantity you ingest. This will avoid worsening the keto flu symptoms and it is just a matter of time before your body finds the right balance.
The return to a normal diet should also be progressive and controlled. The diet period goes from 2-3 weeks for a minimum ketosis effect to 6-12 months for an optimal safety.
Recognise the ketosis and ketoacidosis signs and measure your ketosis. There are many testers available in the market that allow you to know how much ketones you have in your breath, blood and urines. This way, you have the chance to get your ketosis at a level that allows an optimal but safe weight loss.
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