Blood-sugar experiment coming up


Over the next few months, we’ll be testing the impact different foods and lifestyle choices have on blood-sugar levels.

To do this, I will wear a constant-glucose-monitoring device that measures blood-sugar levels 24/7. We recently got the device, and I put it on immediately.

What would you like us to test?

How the device works

1. A blood-glucose sensor and transmitter is inserted into the body.
2. The sensor measures glucose levels just underneath the skin.1 3. A transmitter attached on top of the sensor sends glucose data over bluetooth to an iPhone app.
4. An iPhone app displays the glucose data.

Here’s what the data can look like:

What we’re going to use the device for

First we’ll doing some tests to make sure everything is working properly.

After that, we’ll start testing the impact different foods and lifestyle choices have on my blood sugar. For example, what do you think will happen when I’m:

– drinking coffee,
– drinking alcohol,
– consuming artificial sweeteners,
– eating different types of low-carb foods,
– eating different types of high-carb foods,
– eating dairy,
– eating low vs. high amounts of protein,
– exercising,
– fasting,
– in optimal ketosis vs. not?

We plan to test all of the above and more. When we have tested something, we’ll write a short blog posts about it.

Please note: This is a n=1 self experiment and my findings may not apply to you. I am a 36-year old insulin-sensitive male, weigh 152 pounds, exercise for 10-15 minutes five times a week, with no history of obesity or diabetes.

What would you like us to test?

Feel free to let us know in the comments below.

Earlier tests

Are you interested in my earlier tests? Check out this earlier series of 3 posts:

  1. Why You’re Not in Ketosis
  2. How Much Protein Can You Eat in Ketosis?
  3. What to Eat in Ketosis
  1. The device measures glucose by picking up electrochemical signals from glucose-oxidase reactions in the interstitial fluid.

    Note that the glucose readings from this device are meant to be used for trending only. A regular blood-glucose meter, and a constant-glucose-monitoring device, measure glucose from two different types of body fluids: blood and interstitial fluid. Therefore, the numbers from the blood-glucose meter and sensor may not match exactly.


  1. BobM
    Could you convert it into US units, too? It's too bad you don't take more data, such as ketones and insulin. I find I can only get into high levels of ketosis if I eat a lot of fat. I'd love to be able to use your monitor and cobine it with at least daily insulin and ketones.
    Reply: #31
  2. Will
    Hi Bjarne, really interesting. Where did you buy the CGM? We've (Werlabs) tested flash monitoring with Abbott's Freestyle, but I'd love to get hold of a CGM in Sweden.
  3. Anna
    Thank you for this initiative. I request that you test high intensity exercise as well as gentle walking.

    Fiber is still highly debated and I would like to see how much different types of fiber (soluble/insoluble fiber, resistant starch) raise your blood sugar.

    Also different types of artificial sweeteners, e.g. sugar alcohols (erythritol, xylitol, Maltitol), stevia and Sucralose. I am not very interested in aspartame, saccharin or Ace-K as they are old school and bad tasting.

    Protein powders such as whey would also interest me. Thanks again.

  4. Alastair
    Peanut butters of varying carb content.

    Varies from around 4% to around 10% in standard UK supermarket own brand PB, to over 20% for Hershey's imported American PB.

    Many thanks. What a great experiment!

  5. Valerie
    Timing of meals.

    Do you get the same blood sugar impact from eating a given meal in the morning vs in the evening?

    Also, if you're willing to make a drastic change, I would be curious about the effects of a very low fat diet (Ornish, MacDougall, Pritikin style). Proponents say it reverses diabetes (after a period of adaptation).

  6. Harry
    Fruit would be interesting. I like to include moderate amounts with an otherwise pretty strict low-carb diet e.g. a handful of blueberries with otherwise plain Greek yoghurt in the morning, occasionally a banana before a workout, or a cup of strawberries with heavy whipped cream. Back before beginning a LCHF way of eating, fruit juices for breakfast or sugary fruit yoghurts as snacks were main culprits in my weight gain, now that craving is eliminated and I have lost 40 lbs in a year back to my formerly normal/athletic body shape. But I still like fruit as treats.
    Reply: #26
  7. Roger
    Excellent initiative thanks. Cant wait for results. Im in my 21st week with weight loss now just under 25kg. Loving it and the brilliant resources you have made available on your website. I haven't been at this weight since I was in my early 20's - Im now 58!! but feel much younger and look like 40, according to my wife :)
  8. Jodi
    Drinking low and no sugar carbonated waters.
  9. Angelika
    I'm curious to know if heavy weight training lowers bloodsugar extremely fast.
    And what about Bullet Proof Coffee? Coffee seems to raise bloodsuger - is it prevented by fat??
    Reply: #10
  10. Pierre
    "heavy weight training lowers bloodsugar extremely fast"

    I was about to ask the same, then I read your comment.

    The weight training session should be around 45 minutes, with 5 or 6 differents exercises comprise of 3 set of 8 repetitions.

    Example: squat, shoulder, pec, back, arms, deadlift

  11. Bettina Bartels
    It is great, that you use your body for a (one person) test. But we all know, a womans body works so different than a mens body. So this test will reflect a males body. You know, men lose weight easier than woman. Maybe the blood glucose will also "behave" different? I wisc you could simultaneously finde a female person in your team that will test that device too.
  12. Eric
    When meters can report glucose Insulin and ketones I would like to see low carb vs palio vs sad vs high carb to see I insulin etceteras
    Also compared eating windows 1 8 12 or from the time you wake up till sleep
  13. Richard
    Great initiative. My wife and I monitor the BG of our diabetic 4 year old son so your experiment will be very interesting. Could you also see how stress levels impact BG? As well as the effect during sleep i.e. If you exercise or eat late does it continue to lower or rise. Thanks
  14. Veronica wellman
    I would love to be part of a trial. It could help me lose weight. I s m not diabetic nbut have an endocrine condition and am very hypoglycemic. I can't take much sugar but have to eat every three hours. I find protein better than carbs.
  15. Brian
    I will be very interested to follow your experiment and to read your blog I am particularly intereste in the effect of fasting.
  16. Phyllis martin
    How about working nightshift vs dayshift.
  17. JB
    Test Intermidate fasting and one meal a day
  18. John R. Kerr, Jr.
    I have been an insulin dependent Diabetic for 36.5 years and I am thankful that you are willing to do this. I really want a continuous glucose monitoring system. I will be patiently waiting for the results.
  19. Helbert
    Would love to see the effects of Kefir, Kombucha and other probiotics.
    Other things would be potato starch (raw and ideally from Bob's Mill due to their production process) and Yakon Root as people claim that those carbs are not digested and can actually lower the BG.
  20. 99
    There is no purchase address and no price
  21. Brenda
    High index fruits versus low index fruits. Im so curiuos. I find my sugars are not crazy from what is considered high, so not sure if my meds are doing its job or the exercise.
    Good luck...
  22. oxapodo
    If the device could measure insulin response to all of the above, that would be really useful.
  23. DebbieC
    I would love to try one of these. Each individual reacts differently to foods so one person's results doesn't necessarily mean another will have the same results. I am borderline diabetic and use a glucometer often but it is not as accurate as I had hoped. I used the same sample that the lab used to test my FBS. Lab got 92 and glucometer got 121.
  24. Carla Sturgess
    I'm waiting on mine i tried it for 7 days it was awesome. It beep when its going to low or high. And i controlled my sugar so much better. Can't wait for my phone call.
  25. Jane S
    I'd really low you to see what happens with a big portion of ice cream. It makes my BS go haywire for 48 hours.
  26. Mike
    Fruit would raise blood sugar by varying levels. Obviously something like bananas would be very large response. I recently tested 1 pound of raw carrots and saw a 40 point jump, 90-130. Even carrots contain plenty of sugar.
  27. Richard Garza
    Test high Sugar Alcohol intake & various forms Sugar Alcohols.

    Have heard various Sugar Alcohols affect blood glucose differently. & I'd like to know if high levels affect Legos as well. TIA

    Reply: #39
  28. Kathryn Powell
    I am currently waiting for a cgm. I started the process of getting one about 3 months ago and most recently have been quoted the costs . I'm very excited about this and I think I may have it in around one month. I'd be interested in the effect of steroid injections as I had one in my elbow a few years ago and recently my husband has been receiving epidurals for pain. Also wonder the effects of different drugs such as antibiotics . I know a DM2 will react differently than a non-diabetic so wonder if your experiment is flawed from the start . Good luck and have fun with your experiments .
  29. Audrey
    Would be interensting to know glucose/insulin levels of someone who has extensively used weight loss products (e.g. Herbalife or Cambridge, or any of the sort) and then changed into LCHF lifestyle. Does damaged liver/pancreas cause extra trouble to metabolism, and to what extent? Does one have to cut all carbs in order to manage glucose levels that a damaged liver produces? Also, a glucose/insulin response when eating sour kraut?
  30. Stevie
    Harry - carrots are high carb, ie high GI.
  31. P. Woycheese
    My mother had one but the results are not in the same measurements as blood sugar. Testing is tough enough without having to convert different readings.
  32. Anna
    Exciting! A colleague of mine has been plotting his diabetic wife's blood sugar for years, and he says that the type of protein she take with her meals also affects her blood sugar levels. Fish and egg with the meal have much lower readings than meat with the meal. One way to test this could be to eat two identical meals but to exchange the type of protein from one day to the next. It would be interesting to know if there is any difference.
  33. Keith
    Thanks for doing this N=1 experimentation Bjarte as it is known that in group studies the members do not always adhere to instructions. Since you are going through all these different macros would it be worth it to also record other markers such as weight and body temperature? Could reveal some interesting data over the length of the trial. Good luck.
    Reply: #37
  34. Edna
    Test the new coke with stevia and raw sugar Thanks
  35. Shireen
    I would love it if you could compare the timeframes and degrees of rise from different types of protein.
  36. John
    I'd like to know how insulin-resistant individuals (such as me, and most of us here), respond to the same food and beverages as compared to insulin-sensitive individuals. Thank you.
  37. Keith
    Also blood pressure as this drops significantly when on LCHF or fasting.
  38. Nathalie
    Beside all the proposed foods/drinks to test I'd love to see also the impacts of fat on your blood sugar level. I read an article once that even fat triggers insulin, so would be nice if you could put these data also into the study.
    Btw, I'll love to follow this article, it seems so interesting and important to me :)
    Hope you'll update it soon.
    Thanks a lot!
  39. Julia
    LSee tested Beer and Cachaça. Results were interesting :)

    You can find them here:

  40. MKL
    Yogurt. Particularly Greek. Someone tested yogurt to confirm a hypothesis regarding the consumption of carbs in the yogurt by the cultures but I think seeing the effect on BG would be needed confirmation.
  41. John
    one 8-ounce container / serving of Plain 2% Fage Greek Yogurt and then at another time
    one 8-ounce container / serving of Plain Total (full fat) Fage Greek Yogurt.

    Thank You!

  42. Nathan Stanford
    I want to know does insulin go up eating or drinking artificial sweeteners. Not sure how to test for insulin spikes.
  43. Debragail
    Where are the results posted after testing?
  44. Lory
    It’s January 2019. I am wondering if you have these results posted anywhere yet? Also if you could test 30g of Vitafiber (an isomaltooligosaccharide syrup derived from tapioca) in coffee or tea with 60g of half and half I would be interested if that knocks you out of Ketosis in the morning. Thanks.

Leave a reply

Reply to comment #0 by

Older posts