Ketosis is a process that occurs in the body in times of chronic glucose depletion. When the body runs out of glucose it turns to fat for fuel, and when it does this, it begins to form ketones to burn as fuel hence the word “Ketosis”.
Ancestrally speaking this would have been very beneficial in times of a drought, or other natural disaster where our ancestors were unable to obtain their preferred macronutrient carbohydrates as a source of fuel. This is similar to the cyclical keto diet. However, it is not the preferred state of the body rather a stressed state that the body is in until it can find an ample source of glucose to properly fuel itself.
This diet took hold after findings that showed fasting was effective at treating epilepsy in the early 1900s, and it was in 1921 when Rollin Woodyatt discovered that when in a fasted state your body produces 3 distinct ketones. Later in the 1960s it was found that in the absence of a high carb diet with a high amount of the dietary calories coming from MCT that the body was able to produce these ketones without fasting, and thus created a novel treatment for epileptic children (60,66). But is this diet really beneficial for the average person? Is this optimal for athletes that are trying to optimize their performance on all fronts? Can you really eat fat to burn fat, or does this just cause insulin resistance?
Ketones are not the bodies preferred fuel source, and the body, as shown in research time and time again, does not thrive in the ketotic state, but rather on a glucose metabolism (49,50,51,59)
One reason that many people think that they need to go into ketosis is the thought that they can enhance their performance, but this is a common misconception. There are many studies that show that this isn’t the case, there is no benefit whatsoever, and can even cause a decrease in performance in certain cases and cause a adverse effects on the body when trying to recover (1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 14).
Another reason that many people fall to the ketosis myth is that they believe it is a magic bullet for losing a little extra weight, but this is only in the short term whenever the body is running out of the glycogen it has stored and pushing out excess water. In the long term there is no advantageous effect of the keto diet over any other diet if the calorie are not in check and that a higher carb diet can actually be more effective (5,15, 16, 17, 18, 19, 20, 21, 22). In fact doing this type of diet actually causes the body to not be able to respond to insulin, because it becomes unfamiliar with it the longer that it goes without it and leads to insulin resistance (23, 24, 25, 26, 27, 28, 29, 30, 31, 32).
The keto diet is also very detrimental for the the thyroid, causing massive damage to the thyroid, especially when done chronically (3,33,34,35,36,37,38,39,40,41, 42).
The reason that people also tend to feel pretty bad on the keto diet is because of the lack of diversity in their food. Most foods that are high in carbs are also extremely dense in micronutrients, and it makes it very difficult to get adequate amounts of all the key minerals we need in order to thrive (43,44,45,46,47,48).
Along with the micronutrient deficiencies that can be caused by the keto diet there are a whole host of studies that show different adverse effects of the keto diet, such as acid P, renal tubular acidosis, enlargement of the heart, hyperlipidemia in children, children heart attacks, decreased platelet functioning leading to increased bruising, and increase in oxidative stress (low antioxidant content in the diet) (52,53,54,55,56,57,58,61,64).
All bias aside from the scientific literature that has been discussed it is obvious that a diet that is deprived of carbs is not optimal for human health. There are many complications that accompany the diet and is only necessary in extreme cases such as severe epilepsy. Even in this case when on the diet there has to be extreme caution and constant measures being taken in order to ensure that the people that are on it are properly fueled through their micronutrient status. With constant blood tests and supervisions by health professionals this diet can save live, but unless you fall under this category there is no reason to undergo this diet. There is no benefit from doing it and could have deadly consequences in the long term.