Why do ketone levels vary throughout the day?

By Dr. Stephen Phinney and the Virta Team

Individuals vary in their blood ketone levels (i.e., beta-hydroxybutyrate – aka BOHB) over the course of a day and from day to day. This can be due to variations in dietary carbohydrate and protein from meal to meal and from day to day.

However, different individuals tend to vary in the levels and pattern of their blood ketones. Some people are highest in the morning and tend to have reduced levels after meals (perhaps due to the dietary protein and carbs they consume). Others of us tend to be low in the morning and then rise during the day.

Additional factors that increase blood BOHB are endurance exercise and also after consuming fats containing medium chain triglycerides (MCT) such as butter, coconut oil, or purified MCT oil. In contrast, there is often a steep drop in BOHB after high intensity exercise, the mechanism for which has yet to be proven. This post-sprint drop in BOHB tends to be temporary (lasting for an hour or two), which means that it’s cause is very different from the days-long drop in blood BOHB that one sees after a large carb meal.

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  1. Avatar
    Frank Rogers, PhD March 4, 2019 at 5:34 pm

    Any citations you know of with multi-day ketone curves? Observing that patterns vary among individuals, likely due to many underlying effects (age, gender, nutrition, &tc), I am curious whether any work has been undertaken to systematically record and analyze patterns across subjects, either in your own trials. There are some interesting reports of blood glucose patterns in ketogenic subjects (Virta’s work, of course, included). Any BHOB time-series data on ketogenic subjects?



    1. Virta Health

      Unfortunately, we aren’t aware of any published data that directly addresses that question.


  2. Avatar

    Not sure that canola oil is a healthy fat


    1. Virta Health

      You may find Dr. Phinney’s take on canola oil helpful for understanding why it is used with our patients: https://blog.virtahealth.com/canola-oil-keto/


  3. Avatar

    Is there any information that shows the relationship between measurements of urine ketones and blood ketones? For example, if the urine results are moderate, say 40 mg/dL = 4 mmol/L, should the blood level reading also be 4 mmol/L ? What does it mean if the actual simultaneous blood reading is only .4 mmol/L?


    1. Virta Health

      There is great variability between urine and blood ketones. One of the reasons for this is due to hydration. The better hydrated you are, the more dilute your urine will be and this will cause urine ketones to drop. If you are dehydrated, urine ketones will appear higher than your actual blood ketones will measure. We recommend using blood ketones whenever possible in order to eliminate the guessing game that comes with urine ketones.


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