Many people throw around the term “keto adaptation,” but there is little consensus as to when it happens or what it means exactly. Theoretically, keto adaptation is the process by which the body adapts to burning ketones for fuel after being in ketosis for a consistent period of time.
The body doesn’t just naturally become keto adaptated because burning ketones for fuel and burning sugar for fuel require different mitochondrial enzymes and varying amounts of energy substrates. For this reason, it takes time for the body to burn more ketone bodies for fuel than sugar and adapt to the ketogenic diet.
How long it will take you to become fully keto adapted depends on your genetics, your past diet and lifestyle, and your current diet and lifestyle. Many studies suggest that it can take around 3 to 6 months before the body is completely keto adapted, but some people think it only takes a couple of weeks.
Either way, as long as you are following the keto diet correctly, your body will become better and better at burning ketones for fuel as you accumulate more time in ketosis.