Measuring Ketosis: Timing & Personal Data

Measuring Ketosis: Timing & Personal Data

For some people collecting data about themselves massively aids long term motivation and acts as a reward in itself, while for the less analytical minded it can be a pain in the backside. This article will explain what you need to track, especially to begin with, and how to use the data.

For Good Measure

Tracking progress and measuring your unique biochemistry will help you stay on course with your keto journey. The personal data you gather will help you understand and optimize your body. As you know ketosis is a metabolic state where the body uses fat for fuel instead of carbs.
When you start ketosis you are switching between these two fuel types. That switchover takes a few days and can include symptoms called ‘keto flu’. For most people the symptoms are mild and are reduced by drinking more water. This means getting into keto is not instant. Your body needs a few days to adjust. Some people take longer, it depends on body type, activity levels and food intake.
You will get into keto more slowly if: you binge the day before you start, you don’t do any exercise, or you are dehydrated. Conversely, if you want to get into keto more quickly: restrict your carb intake to 20g or less per day, exercise on an empty stomach, and keep well hydrated.
Your body is able to switch quickly to using carbs, but slowly to using fat. This means you have to be careful that you stay in ketosis. You can’t just dip in and out of it when you fancy. You’ll never get the same rapid benefits if you are frequently changing between the two fuel types.
Ideally you want to reach an optimal level of ketosis. This is when your body is using fat for fuel as much as possible: you can measure when this happens by checking for ketones in your body. The body breaks down fat into ketones before it is used for energy. You can measure these ketones in your blood, breath or urine.

The Ketone Zone

The Keto Zone Graph pictured above shows us that the optimal level is when blood ketones have reached 1.5 (millimolar). A reading over 1.5 indicates the body is definitely using fat as the primary fuel. This optimal, green, zone extends to about 3.0 millimolar. After 3.0 you get into starvation ketosis, which sends the wrong signals to your body.
On the far right, in red, is Ketoacidosis, over 10 millimolar but this is virtually impossible unless you have severe insulin-dependant diabetes. The aim is to keep your blood ketone level in the optimal zone of 1.5 to 3.0 millimolar. You can do this by measuring your blood ketones or by observing physical symptoms. Honestly, especially in the early days, it is much easier, and kinda fun, when you can tell for sure you have hit the sweet-spot of optimal ketosis.

Testing For Keto

The urine test strips are very cheap and pretty simple to use but not very accurate. The blood and breath meters are more expensive, but still very affordable for most people. If you think it would support you to gather data, then invest a little to make it easy.
If you get a meter, the readings can reveal what is going on inside, for example: Light Ketosis, between 0.5 mmol/L – 0.8 mmol/L. This means the body is using some fat for fuel, but it is also using carbs. This could be from carb stores – glycogen in the liver and muscle, or carbohydrate in your diet. Either you are in still switching over or you have eaten too many carbs.
Being able to track the level of ketosis will help you feel like you are making progress. It will also make it less likely that you will cheat. It can also help you spot carb creep and identify danger foods. For weight loss the ideal is Deep Ketosis at 1.5 mmol/L – 3.0 mmol/L.
Knowing blood ketone levels can also help you spot patterns in energy and mood related to your nutrition. Record your results for just a few days to see progress and feel a sense of accomplishment as you enter the optimal keto zone.
In addition to recording blood ketone levels many people choose to track: calories, exercise, food, water and weight. Tracking all this information about yourself might seem overwhelming at first. Fortunately, there are some handy free apps available that can make this process a lot simpler. One of the best apps is MyFitnessPal, which captures most of the information for you and will help you stick to your macros.

Physical Symptoms

By looking out for symptoms (like keto breath, thirst, more urination and lack of appetite) you will know if you are in ketosis, but, using a test strip, or ideally a meter, you will know exactly where you are on the keto zone graph. Keeping a journal can also help you spot patterns in personal energy levels, mood, emotional reactions and other useful personal cues.
Tracking progress towards personal goals will help you maintain motivation when things feel more difficult and giving yourself rewards can incentivise pushing yourself a little if needed. If you want to lose weight you can track progress by weighing yourself, but we recommend doing so no more than once a week. Before and after pictures can also help you see changes in your body shape. If you want more mental clarity then you can track improvements by scoring your own perception of mental clarity at various times through the day then plot your results.
If you goal is improved fitness then you can track recovery times, lap times, reps and sets or any other measurement of performance that you want to improve. Keeping a food diary which also tracks when you eat will help you find correlations between your physical body, mental and emotional state and dietary choices.

Know Thyself

Knowing and understanding your own body and mind can be immensely empowering, creating a personal strength most people never begin to master. Once you become more familiar with your body’s unique response to ketosis you can choose to speed up your progress or even slow it down by changing your macros, exercise or eating times. You get to direct your journey with ketosis and by using personal data you make the best decisions for you.


  • Measuring data is an immeasurably helpful way to understand where you’re at with your keto experience
  • There are various methods you can use to know if you’re in keto using: urine, breath or blood
  • It can also be useful to track calories, exercise, food, water and weight
  • The more data you record the more feedback you have to adjust your endeavours accordingly if you like data that is!

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