If you haven’t felt what ketosis is then the best way to do it is to use exogenous (external) ketones. For example, you can take about 10 grams of the Potassium BHB ketones salt that I periodically use to enter ketosis.

After taking 10 grams in a fasted state (about 14 hours into fast) it takes about 15 minutes to enter ketosis. And at the peak it reaches about 0.5 mmol/l of Acetone ketone in the breath.

Pay attention, that exogenously induce ketosis doesn’t feel that good. You may experience a light headache and overall feeling of discomfort. What is interesting during prolonged fasts of 40 hours long I haven’t felt discomfort to the same extent that exogenous ketosis caused.

Also, the physiology of exogenously induced ketosis is very different than the endogenous (native) one that happens during prolonged fasting.

The main difference being fat mobilization: endogenous ketosis happens when free fatty acid released from fat storage are turned into ketones, while during exogenous ketosis no fat is mobilized and to the contrary fat usage is inhibited.

So there you have it, exogenous ketosis is just 15 minutes away, but it wont’ help you lose weight. It can definitely help in preventing, or slowing down early onset of dementia, it can help reduce epilepsy seizers, and can improve sport performance though.