I Used a Continuous Glucose Monitor for 28 days, This Is What I Learned.

The Method:

The monitor that I used is the Freestyle Librelink Sensor that connected up to the Freestyle Librelink app on my phone. Note that you cannot get the sensor or app easily without a prescription in the United States. It was not simple or inexpensive to acquire this system. If you are curious about how to obtain one without a prescription, I would be happy to share my process with you. 


Since I had no need for a prescription (I am not diabetic or pre-diabetic) I completed this as an experiment to learn more about my body. 

Every year I have had my fasting blood glucose levels tested. Every year the range has been acceptable. These tests were completed by a previous employer’s insurance company during the annual health screening. 

Once I no longer worked for that company I sought out a company to test my own levels. During that test, I learned that my fasting blood glucose was acceptable, but not optimal.

I had also recently read Robb Wolf’s book Wired to Eat and he mentioned using a continuous glucose monitor to learn what foods you may have a sensitivity to. The test recommends a 30-day elimination diet with mostly proteins, fats, and veggies to create a baseline. Then after the 30 days test one food a day from a fasting state consuming with various sources of starches to see how your body reacts. 


I did my test somewhat similar to that, but with starting with 2 weeks of testing of what my diet currently was. Then 30 days of eating primarily protein, fats, veggies, and some fruits. Then using a second sensor for another 2 weeks. 

What I learned:


Your fasting level will fluctuate not only day to day, but hour to hour. My fasting rates at 6 am (appx 10 hours fasting) were different than my rates at 8 am (12 hours fasting) vs 14 or 16 hours fasted. And those numbers weren’t necessarily on a consistent trend, for example, the longer I fasted did not guarantee my levels were closer to optimal levels. The levels would bounce around. 

Levels Change During Exercise:

My blood glucose levels would rise with exercise. The reason makes sense, but something I did not consider prior to experimenting. The muscles are looking for the extra energy to support the increased demand on them, therefore more glucose is released into the system. 

Foods That Increased Levels:

The foods/beverages that I thought would cause an increase in my levels for the most part did create an increase. 

The biggest culprits for me; juice, energy drinks (even sugar-free!), white rice, white corn tortilla chips, flour tortillas. 

Surprising Findings:

The foods I expected more of an increase from did not cause the levels to rise any higher than other carb sources. For example, any source of straight-up sugar; baked goods, or candy. But to be honest, I never had quantities sufficient enough to be considered excessive and rarely if ever ate them in exclusion. 

The serving size of white rice and tortilla chips was closer to excessive and definitely exceeded one serving of a cupped handful. 

The juice was no more than 4 oz and considered to be of high quality. 

If I drank alcohol (tequila on its own, or a margarita), my levels would spike in the middle of the night waking me up. 

Combinations of Macros:

The times that I did have a serving or more of some other starchy sources (potatoes, legumes, whole wheat bread) they were always in combination with a protein source and/or a fat source. That would increase my levels, but not out of an acceptable range.

Fruit is another source of starch that did not significantly impact my levels. The levels were even less impacted if I ate the fruit with a protein source. 

White rice, by far, seemed to spike the levels the quickest and have the longest effect on the levels. Regardless if I ate it with protein, veggies, and fat. 

Keeping Levels Consistent:

With a solid day of getting in veggies, fat, and protein, my levels would be in an optimal range and rarely (maybe once) drop to the low range. I could stay in a fasting state without the levels being affected for a longer time than when I had any processed foods. 

If I had a source of processed carbs levels would rise and then drop leaving me feeling uneasy and hungry within about 2-3 hours. 

My fasting levels were consistently more in the optimal range after the 30 days of eating exclusively protein, fruits, veggies, and fats. 

I Am Not A Scientist or a Doctor:

I am just a curious person. This is by no means an exhaustive study (so many foods I could have tested, so many variables I could have played with, so many methodologies I could have approached more scientifically). 

The point isn’t necessarily to report that staying away from white corn chips and white rice is what you must do, but an example of gathering data to learn more about my body and how it operates. 

This testing helped me realize certain sensations in my body created by certain foods that I ate. Helping to inform me if I wanted to continue to consume those foods, or the timing of it, or in what combinations I wanted to eat it. 

You and your body will have different reactions than mine. I encourage you to experiment with tuning into your body’s feelings and reactions to different foods, sleep patterns, exercise, stress, and stress-relief, etc.



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