When I looked in to Ketosis it stated that after about 3 weeks with out carbs the body will start to become more efficient with using fat as energy for the brain and body. The confusion is do that mean dietry fats or body fat cells.. What fat does the body start using because somthing has to replace glucose since that's what the brain runs off of
The body fat will be burned for energy. The body will also create any needed glucose via gluconeogenesis. There are essential fatty acids, as in fats, and essential amino acids, as in proteins, but there are no essential carbohydrates. You don't need to eat carbs at all, none. Dietary fats are needed to build and maintain your body. You need fat for your brain and nerves, most of your brain is made of cholesterol. You need fats for your immune system to function optimally. You need fats for the body to create hormones to build and grow your body and muscles, and to aid in protein uptake and cell formation. In the high fat, moderate protein, extremely low carb dietary environment that is the keto diet, your body realizes that you are getting plenty of fat in your diet, for all the necessary body functions that fat is essential for, so it has plenty of fat available, and isn't starving, so it freely burns all stored body fat for energy, cutting the body fat, and giving you muscle definition. That's how the keto diet works for you.