Net Carb vs Blood Sugars – The Quest Protein Bar Test

This entry is part 1 of 3 in the series Net Carb or Net Farce?





 If you can’t view YouTube or if you want to download these videos, then . . .

SEE PART 1 – Net Carb Test — Part 1 (3 1/2 Minutes)

SEE PART 2 –  Net Carb Test — Part 2 (4 1/2 Minutes)


Editor’s Note:   Many companies advertise high-fiber, “net carb” products as safe for diabetics to use liberally, but many people with diabetes have observed that these products can drive up their blood sugars more than expected. When people make these observations one person at a time, they may feel like outliers, especially in the face of industry and scientific studies that state that net carb products do not raise blood sugars.  But some experts and advocates have persisted at looking more closely at “Net Carb” product, includingJimmy Moore at his Livin La Vida blog, David Mendosa through Diabetes Central, and Ron Rosedale through his Facebook blog.

To check this out from a first-hand perspective, Boulder’s Very Low Carbohydrate Diabetes Support Group conducted a citizen-based “test” of a “4 net carb” Quest Protein bar.  The Quest company donated the bars for this test.  Type II diabetics Barry Erdman and David Mendosa, Type 1 diabetic Jeff Roaderick and others helped develop the protocol.  The group is aware that their experience is not a scientifically conclusive test, due to the small sampling size.  Nevertheless, this first-hand experience, in a group setting, led many of the roughly dozen people who participated to wonder whether some other community groups might want to conduct similar tests, on similarly labeled “net carb” products.  Perhaps, together, community groups can find some clearer answers about these products than those being provided right now by food  companies and by regulatory agencies such as the FDA.  Questions this Boulder citizens’ group have include:

1.  What’s a good rule of thumb for calculating the effect of fiber carbs on blood sugar?  (The group is inclined toward 1 fiber carb = 1/2 regular carb)

2.  Why do some people have a stronger response to fiber carbs than others?  This group, for instance, is wondering whether insulin resistance and insulin production affect blood sugar response.  Additionally, this group wonders whether inflammatory responses to substances such as glutens, grains or dairy might affect blood sugar response.

3.  How representative is this result?  In this group,  half the participants saw a 50% rise in their blood sugars, within 1 hour of eating the Quest Protein Bar.

As an additional note, in this experiment, we tested Quest Protein Bars that were donated by the Quest Protein Bar company.  That company is continuing to work with us to figure out what, in their protein bars, seems to raise blood sugars in some people.  Is it the fiber?  (their science studies seem to say no)  Is it the whey (it shouldn’t, supposedly, but we’re going to check it out.)


TEST PROTOCOL (Provided by Jeff Roaderick)

If any other groups are interested in trying this kind of test, here is the protocol we used:

This is the meeting that we are conducting our own group experiment: testing how our blood glucose reacts to a low-card food. Here is the information about the experiment:

 Food Item : one peanut butter Quest Bar  – David Mendosa will provide.

Testing protocol:

REQUIREMENT # 1:  Eat Breakfast BEFORE 8 AM
REQUIREMENT #2:  Bring Your Own Glucometer to the test/meeting

Test 1: Fasting Blood Sugar Before Breakfast AND before 8am

Test 2: 10:15 am (Just before eating Quest Protein Bar)

Test 3: 11:15 am (This is the 1-hour after eating Quest “Net 4 Carb” Protein Bar

Test 4: 12:15 am (This is the 2-hour blood sugar test, after eating Quest “Net 4 Carb” Protein Bar

REQUIREMENT #5:  Fill out forms that:

1.  Record Your Blood Sugars at each testing time

2.  Identify your Diabetes As:  Type1/Type2?

3.  Tell whether you exercised in the morning, before the test
4.  List any medications taken in the last 24 hours (including Insulin doses, and time of dose)
5.  Anything else – (for instance, if catching a cold or flu, which tends to increase blood sugar levels)
Based on what we learned from this test, we might consider the following additions:
1.  Please list what you ate for dinner last night, how much, and when
2.  Please list what you ate for breakfast this morning, how much, and when
Series NavigationNet Carbs vs Fiber Carbs – Jeff vs 1 net Carb Bread

  7 comments for “Net Carb vs Blood Sugars – The Quest Protein Bar Test

  1. Jess
    July 28, 2014 at 4:58 am

    Type 1 diabetic…Quest bars make my bgl sky rocket, even when I dose for the full carb amount! The best I can figure is that it’s the use of erythritol in the bars that’s doing it…despite all the info about this product having 0 effect on blood glucose, my experiences with it tell me otherwise…

  2. Deb
    May 28, 2014 at 3:57 pm

    After eating 1/2 of the chocolate-peanut butter Quest bar my blood glucose level was 228. YIKES. can’t do these.

  3. Molly
    March 24, 2014 at 11:58 am

    Within an hour of eating this bar I felt like I was doped up on sinus medicine and was jittery. I’m not diabetic as far as I know but something in my body did not react well with these things. On a lighter note, they tasted really good…go figure.

  4. Dotty
    September 20, 2013 at 7:05 am

    After one Quest Bar (Chocolate Chip Cookie Dough), my blood glucose spiked from 83 to 134. I am not a diabetic. But, dang. That thing acts like a candy bar. Never again.

  5. PatB
    July 2, 2013 at 8:57 am

    Thank you so much for posting this information. I am Type 2 diet-controlled. GNC touted these bars as great for diabetics so I tried a few. I didn’t understand why, after eating a Quest bar, I was tired and dizzy after a hour. It felt to me like my sugar was up but it couldnt’ be, right? After all, only 4 net carbs. Wrong. I am staying away from these bars from now on.

  6. Mari
    November 6, 2012 at 7:31 am

    I ordered these bars for my husband who is Type II diabetic. He has been doing very well on a low carb diet, and dilgently testing every new food that he eats. The Quest bars definitely raised his blood sugars, so they are a no go. Atkins also raises his blood sugars. Still on the search for a low carb bar that he can eat. So far homemade is the only way to go at this point. I am still having trouble believing the net carb hype.

  7. Brian
    October 4, 2012 at 8:48 am

    These bars a bad for diabetics – my blood sugar sky rocketed after eating one bar. I usually have whey protein and nut butters daily, so I can’t figure it out – I honestly think they’ve manipulated the nutritional information.

Comments are closed.