After you give the keto lifestyle a few days, the easiest way to see if you’re in ketosis, and know to what level of ketosis you are in, is to conduct a blood test using a blood ketone meter. You may see your levels of ketones start rising from 0.1 mmol/L to 0.2, then 0.4 or higher. You are officially in ketosis when your ketone levels reach 0.5 mmol/L! (you can learn all about how to test here and what your ketone levels should be here.)
Testing is the only accurate way to know when you enter ketosis (and blood testing is way more accurate than urine or breath testing), but there are also telltale signs that you’re on your way.
Many people new to the low-carb diet get symptoms or signs of ketosis that combined are not-so-fondly known as “the keto flu.” These symptoms include fatigue, dizziness, nausea, muscle aches, bad breath (smells like nail polish remover) and headaches. Though they’re no fun, don’t worry! Many of these symptoms are from electrolyte imbalance, so you can alleviate them by making sure you get enough magnesium, potassium, and sodium. Foods such as avocado, pumpkin seeds, Ultima electrolyte powder, bone broth, and pickles, are delicious ways to ward off symptoms. Regardless, you are likely to be in the clear after the first 3 to 5 days of beginning to get into ketosis.
Once you’re solidly in ketosis, common signs of your status are a metallic taste in your mouth (this is from the ketones), a much more manageable appetite, and the ability to go longer between meals without feeling hungry. Finally, one of the best telltale signs you’re in ketosis: a massive and sustained increase in energy as your body begins to use body fat and fat from your diet as its primary energy source!
That said, these “signs” are subjective and are not experienced by all keto dieters within the first week, month, or at all, so don’t worry if you don’t get the keto flu or have the metallic taste. Just keto on!