The keto pitch: (as far as I understand) You have a carb-heavy lunch, your insulin spikes to process this, then after the glucose is processed the excess insul

The keto pitch: (as far as I understand) You have a carb-heavy lunch, your insulin spikes to process this, then after the glucose is processed the excess insulin causes a drop in blood sugar (a kind of undershoot in the control system). This is felt as a crash in energy levels. A keto diet prevents this by avoiding carbs, hence avoiding large swings in insulin and blood sugar levels. Hence keto diets are supposed to provide very consistent energy levels.