Ketosis is when your body metabolizes and uses fat — instead of the blood sugar (glucose) it traditionally uses — to fuel your body and provide energy for your daily activities and exercise.
Achieving ketosis on a low-carb, keto diet takes approximately 72 hours (3 days), according to research published in the Special Operations Medical Journal. However, other studies have found that it may take as little as two days, or as many as 10 days.
During ketosis, your levels of insulin drop. This causes your body to release fatty acids it was previously storing. Your liver turns these fatty acids into ketones, which is then used as energy.
A state of ketosis can be triggered when you limit your carbohydrate intake to 50 grams or less a day. Everyone’s body is different, and some people need to cut their daily carbs down to as low as 20 grams to hit ketosis.
However, it’s safe to say that most people enter ketosis within two to four days of starting their keto diet.