The Ketogenic Diet or – Keto Diet – limits carbohydrate intake to around 50g per day or 5% energy intake – whereas a low-carb diet has no definition. Personal perceptions of low carb may be completely different to another person’s.
In fact, on a ketogenic diet, the macronutrient content would be similar to like 5% carbs, 15% protein and 80% fat. This is according what we are currently giving people for a research study we are running at Anglia Ruskin University, Cambridge.
This is the key difference between going keto and low carb, as this very limited amount of carbohydrate depletes the body and brain of glucose. This is where “keto-adaption” takes place and the body shifts away from carbohydrate metabolism and towards predominantly fat metabolism both at rest and during exercise.
However, the central nervous system and brain cannot do this as fatty acids cannot cross the blood-brain barrier and therefore the increase of blood ketones (b-hydroxybutyrate, acetoacetate and acetone) reaches concentrations of 2mmol/l or more. This is why for the first few days on the diet you may feel tired, lethargic and lacking concentration.
Ketosis & Ketones
Ketone bodies are a major source of energy during periods of fasting or severe carbohydrate restriction (