By now you probably know a ketogenic diet is designed to keep sugary carbohydrates out of your system, allowing your body to burn clean fat sources as energy, which is the ordinary way humans evolved to transform food into energy. The diet helps organize your food intake to keep healthy fats high, proteins at a moderate level and carb intake to an absolute minimum – and it works! Keep carbs off the menu for just a short while and your body soon becomes adapted (more like re-adapted) to using up fat for energy. Your metabolism stabilizes and body fat storage heads towards equilibrium.

But how do you know for sure if your body is ‘in ketosis,' or burning fat-derived ketones for energy, rather than glucose (sugars)? That's the desired state and the ongoing goal of the keto diet, but HOW DO YOU TELL?

There are 5 ways to measure ketones in your body once you've become ‘keto-adapted'. If all goes well, your diet, supplemented by a bit of regular exercise keeps blood sugar at a stable, healthy, low level. This reduces insulin sensitivity and reduces inflamation throughout the body, as your metabolism turns into a fat-burning furnace!

1. First, let's consider the method most people overlook for testing: How do you feel? This is a subjective test, unlike the more technical, objective tests on the rest of the list, but it'd important! If you're burning fat for energy, rather than sugar, you'll be relaxed, mentally sharp, full of reserves of calm energy and you won't feel the hunger pangs that lead carb-addicted bodies to snack all day.
2. The next most common test method for people new to a keto diet are urine test strips. This is a cheap and easy test, costing just a couple of dollars per month for the test strips, but it's not a good, accurate test. That's because you're testing excess ketones excreted in urine, rather than the ketone levels in the bloodstream. Ketone concentration in urine can be affected by the timing of your tests, how hydrated or dehydrated you are, and a host of other factors. It's OK, initially, but remember what the strips test and the potential weakness of the method.
3. Blood ketone testing units are the next most common test type. This test is the most accurate way to measure ketones in your blood, but it does require a blood testing unit (similar to a blood-glucose test machine). It also consumes test strips specific to your chosen machine and, of course, you must test your blood, so that means a rather expensive setup with a painful jab for each test.
4. There is also the option of testing ketones via breath sample analysis. This option is less accurate, but it doesn't require stabbing a finger for blood and once you own the (slightly pricey)
   test device, you don't need to feed it expensive test strips all the time! A Keto Acetone Breathalyzer will be affected by water and alcohol consumption levels
5. Finally, the least common test is a blood glucose test. Some of the blood ketone test devices also double as blood glucose testers, as long as you use the appropriate test strip. The test is functionally the same as for the blood ketone test: you must jab a finger for a drop of blood, feed that sample via test strip to the machine and wait for a result. As Dr Jockers explains, glucose testing is a useful indirect test of blood ketones.
   

   “When one is in a ketogenic or fat adapted state, they can be at a hypoglycemic level (under 70mg/dl) and feel very good. They will have lots of energy, mental clarity and stamina, healthy mood and behavior and be able to sleep well.

   This is a sign their body has adapted to using ketones and is not reliant on sugar as its primary fuel source so the body is no longer concerned with keeping blood sugar levels up in order to survive.

   I instruct my clients, that if their blood sugar is between 50-75 mg/dl and they feel very good, mentally sharp, energetic and relaxed on a continual basis, then they are keto-adapted.”

Dr. Jockers outlines these methods in detail in his helpful article.