does our body switches energy production from ketosis and glucose
Although glucose is the main source of fuel for most people, these fatty acids are used by the brain cells when carbohydrate or food intake is low. In simpler terms, since you have no more glucose or glycogen, ketosis kicks in and your body will use your stored/consumed fat as energy. Ketosis is pretty amazing, and in fact, gets even better. Studies show that the body and brain actually prefer using ketones, being able to run 70% more efficiently than glucose.