Nutritional ketosis is a metabolic state whereby your body has become ‘fat adapted’ which means that it now uses fat for fuel, instead of glucose (sugar). It is not a high protein diet, it is a HIGH FAT diet. When done properly, it consists of around 5% of total daily intake from carbs; around 25% from protein and 70% from fats. It is also important to note that it takes the body full 6 weeks to get completely fat adapted. Yes, you will enter ketosis earlier (it’s all individual, but the full adaptation with all the benefits will occur only after 6 weeks)

When in nutritional ketosis, the body to produce ketone bodies: acetone, acetoacetate and beta-hydroxybutyrate which are know to:

  • Send the satiety signal to the bran
  • Are muscle sparing

This here, is the difference between nutritional ketosis and low carb diets. Low carb diets are very unpleasant, as the body is struggling to find fuel for energy production. Still having some glucose, but not enough to enter ketosis and not nearly enough to function normally. This will be at around less than 130g pf carbohydrates per day, and more than then 50g.  This is a state where the body want to run of glucose, but hasn’t got enough of it, and can’t adjust to run on fat, because glucose is still in the picture.

The organ that is the primary consumer of glucose is our brain. Therefore, it is important to have enough glucose for the brain to function, or not at all (for most of us <50g) so that the body can produce ketone bodies which the brain can use as well. The brain does this so that glucose is spared for red blood cells which can only use glucose since they don’t have mitochondria (glycolysis happens outside of mitochondria).

Positive sides of the state of ketosis:

  • Ketone bodies also send a satiety signal to the brain, so we don’t feel so hungry as we otherwise would on low carb.
  • By regulating blood sugar levels, some people tend to have enhanced cognition, concentration and focus.
  • Ketone bodies are muscle sparing
  • Enhanced cognition
  • Positive effects for treatment of certain chronic illness (Alzheimer, epilepsy, cancer, auto-immune)

So, this all sounds great, what are the drawbacks?

  • Some people are just naturally, better fat oxidisers whilst others gave a better glucose metabolism, Clearly, the first group will feel better on this diet, rather than the latter. Typically, people who have good glucose metabolism, won’t feel as good on a high fat – low carb diet as the others.
  • Some types of exercise, specifically HIIT (High Intensity Interval Training as well as bodybuilding style of training) just cannot be as efficiently fuelled with fat as they can with glucose. Therefore, there is only a certain type of training that should be performed when doing keto.
  • Lack of dietary fibre, when on keto diet, is one of the main reasons this nutritional approach should not be practised for prolonged periods of time (year-round). This is a major drawback that can not be disputed.
  • Even though ketones have a muscle-spearing effect, empirically it has been shown that majority of people will lose some muscle mass. Maybe not as much if ketones weren’t present, nevertheless, some muscle wastage does occur.
  • Similarly, it is not optimal when it comes to building lean muscle neither.


Ketogenic diet has definitely got it’s place, when it comes to fat loss diets as well as in treating some chronical diseases; However, it has many limitations and needs to be exercised correctly.