Regularly in my practice I meet people who are suffering from the again popular trend, ketogenic diets. Lost weight (often we are talking about dozens of kilograms) is returned with a surplus. Neither a very low calorie diet nor fasting are helping. This blog is dedicated to those curious about what are those ketogenic diets and how they work.
Glucose is the main fuel for our brain
Glucose is the major fuel for most cells of our body. A small amount of glucose is stored in the liver and muscles. This reserve is called glycogen. Glycogen reserve is used at the times when glucose from the foods is not available, as our body needs glucose virtually every second. About one third of the glycogen is stored in the liver. The liver releases glucose into the blood as needed. Glycogen stored in the muscles (the remaining two thirds) is consumed during intense exercise. A very small amount of glycogen is stored in the brain. It is believed that this mini-reserve is the fuel for those emergency times when the flow of glucose is completely absent.
In the absence of glucose from the foods the body glycogen will be depleted in less than a day. This is if you don’t exercise. With intense physical exercise the reserve will last for several hours.
Glucose is the preferred fuel for the cells in our brain, nerve cells and developing red blood cells. Protein from our body can be converted to a certain degree in the glucose. Adipose (fat) tissue cannot be converted into glucose. Thus, when a person does not replenish glycogen reserve by eating carbohydrates, body proteins (including muscle tissue) are destroyed in order to produce glucose and fuel her body.
What is ketosis
Chemical reaction in which glucose is obtained from protein is called gluconeogenesis. Only an adequate intake of carbohydrates can prevent gluconeogenesis. Inadequate intake of carbohydrates (as in the case of carbohydrate-free diets) directs the metabolism of a perilous direction. If the body gets less carbohydrate than the brain needs to obtain the required glucose, fatty acids are broken down and form an alternative fuel called ketone bodies. Ketone bodies provide an alternative energy for some brain cells during periods of fasting. Some brain cells, however, can only survive on glucose. Thus during fasting or prolonged carbohydrate-free diet (these two states are practically equivalent for the body) muscle protein will always be broken down to produce glucose.
The brain and nerve cells consume about half of all the carbohydrates consumed by us with food
Keto acid, from a chemical point of view, is a ketone with an acid group. A small amount of keto acids in the body is normal. But when the production of ketone bodies exceeds the demand, they accumulate in the blood and this leads to a state known as ketosis. Ketosis violates the acid-alkaline balance of the body. Elevated levels of keto acids in the blood is called ketoanaemia. Excess keto acids are excreted with the urine, a condition known as ketonuria. The acetone breath is a sign of ketoanaemia.
In order to prevent the destruction of muscle protein and ketosis, we need to eat every day at least 50-100 grams of carbohydrates. By the way, the brain and nerve cells consume about half of all the carbohydrates consumed by us with foods (about 500 calories a day).
What are the dangers of keto diets?
Keto diets are high in protein, often very high in fat and are virtually carbs-free.
Even if your diet contains a lot of protein, loss of muscle mass is absolutely inevitable
As described above, our body absolutely needs glucose for normal functioning. The most logical source of glucose for it are carbohydrate-rich foods. In times of deficit of carbohydrates from food the body will produce glucose from own protein. Even if your diet contains a lot of protein, loss of muscle mass is absolutely inevitable, since your diet in any case will contain fewer calories than you need (otherwise losing weight is principally impossible). Yes, keto diet can lead to significant weight loss, but most of that weight is your own tissue protein. A balanced (i.e., with a good ratio of fat, protein and carbs) low-calorie diet is much healthier since it leads to the loss of body fat and preserves more muscle tissue.
Ketosis can cause nausea, constipation, dizziness, loss of balance, inability to concentrate, fatigue. Ketosis can dramatically worsen existing health problems, especially kidney disease. Diets with a very high protein content, and more so if you follow them for a long time, can lead to kidney stones, osteoporosis, cardiovascular disease.
Three facts about ketogenic diets
Fact 1: Keto diets do not lead to a greater loss of fat tissue than other types of diets.
Fact 2: Keto diets lead to increased levels of uric acid in the blood. This in turn can cause or worsen kidney disease, and also cause inflammation of the joints in people predisposed to gout.
Fact 3: The body sees keto diets as fasting. After it is over, the body will try hard store all incoming energy. In the form of body fat, of course. Therefore, shortly after a ketogenic diet the weight comes back, and fast, and it exceeds the weight before the diet.