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Keto Product & Lifestyle Testing w/CGM

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Last Updated on April 8, 2021

What’s a CGM?

A device I wish everyone could have access to.

A continuous glucose monitor (CGM) is made for diabetics (both type 1 and type 2) – it’s a life changing/saving device. Those that need to monitor glucose levels are able to see (in real time) how foods and activities impact blood sugar.

I’m not a diabetic, I’ve been wearing a CGM for over two years (on and off) to ensure that foods we produce at cardnl won’t raise blood sugar (are safe for diabetics and those on a Ketogenic diet). I also wear it to learn about me. The data I get from wearing a CGM is priceless.

Foods that Impact Blood Sugar

Keto Diet Blood Sugar
Standard Diet Blood Sugar

In this post, I’ll be showing results of how foods and activities impact my blood sugar. This post is not to be used as personal medical advice. These are my results and my opinions alone. I am not a doctor and this information is not to be used as medical advice.

In this post, I’ll include my opinions on why blood sugar levels changed (which ingredients were likely to blame and why).

Note: Everyone is different. Something that impacts me a certain way may impact you differently. However, ingredients that add sweetness to packaged goods almost always have the same reactions across demographics (generally). If you’re insulin resistant (more later) carbs and certain activities and lifestyle may have a much more dramatic impact for you.

What happens when you consume carbs?

Let’s see a baseline for items that are NOT considered Keto first. This will help you visualize what happens when you eat sugar/carbs. In this example, I consumed a dinner with added sugars in the sauce, quite a bit of protein, and limited fats. After dinner, we ate regular ole’ cookies from a local cookie shop. This blood sugar spike and drop pattern happened all night long and then regulated by morning.

Dinner and Sugar Cookies

Carbohydrates are converted to sugar/glucose. Glucose is absorbed into the bloodstream, insulin is utilized to transport glucose to cells within your body (for use).

Overconsumption of carbs (similar to the CGM data here) over an extended period of time is one major cause of Insulin Resistance.

Gauging Glucose Levels

General recommendations on fasting glucose:
Healthy Fasting: 70-100
Risk of Diabetes: 100-125
Diabets: 126+

Insulin Resistance

The hormone insulin helps control the amount of sugar (glucose) in the blood. When a person has insulin resistance, their body’s cells don’t respond normally to insulin. When this happens, Glucose can’t enter the cells easily, it builds up in the blood (more glucose in the blood). This can eventually lead to type 2 diabetes, heart disease, and much more.

Keto Products as a Partial Solution

The reason we created cardnl: to provide treats for those trying to reduce sugar and be an aid in the reversal of pre diabetes, type 2 diabetes, managing a low-carb/Ketogenic diet, and to help manage type 1 diabetes. Our goal is to provide treats/products that allow those needing and wanting to reduce sugar consumption an option and outlet for treats without the fear of high blood sugar and instability. Great taste, texture, and no rise in blood sugar is our ultimate goal.

The following images are from my personal CGM results testing our products, products we sell online and in our store from other brands, and products that claim to be “Keto” or “Sugar Free”.

CGM Product Testing

At the time of this testing: I’m a healthy, 40 year old male (6ft 185lbs) – I generally eat low carb (and mostly “paleo”) however, I do not count macros or calories. I generally intermittent fast 5 days a week.

Let’s get in to the results!

Electrolytes & Caramel CGM Test

Salty Lemon Twist Electrolytes – No impact on blood sugar, electrolytes are an essential part of any low carb or ketogenic diet.

Caramel Sauce – Sweetened with Allulose and no impact on blood sugar.

Reb M Stevia

(in the electrolytes) – Highest quality stevia with no aftertaste (unlike some other variations of lesser quality stevia options). Stevia does not impact blood sugar. Also used in cardnl Boone Bars.

Boone Bars (cardnl)

Ingredients: Cocoa Butter (fair trade), Freeze-Dried Blueberries, Whey Protein Isolate (with sunflower lecithin), Blanched Almond Butter, Unsweetened Coconut, Hydrolyzed Collagen (bovine), Alkalized Cocoa Powder, Non-Alkalized Cocoa Powder (organic), Redmond Real Salt, Stevia (Reb M)


(in the caramel) – Allulose is sourced from the fructose in corn. The corn is broken down into starch and fructose, the fructose is then converted to allulose via an enzymatic conversion process. The enzymes – which serve as processing aids – are not in the final product. There are no residual corn proteins in the final product either. Allulose has been proven time and time again to NOT RAISE BLOOD SUGAR.

Salted Caramel Sauce (cardnl)

Ingredients: Non-GMO Allulose, Cream, Butter, Vanilla, Redmond Real Salt


(in the caramel) – Dairy can be tricky as some dairy products have sugar. In this particular case, the dairy used doesn’t contain sugars enough to show a glucose spike. However, beware of hidden sugars in products like milk and yogurt.

Bang Electrolytes and Champion Bars CGM Test

Bang Energy‘s main sweet ingredient is Sucralose. I’ve written about Sucralose here. Sucralose does NOT impact blood sugar.

Blueberry Crunch Champion Bar by cardnl does NOT impact blood sugar. The sweetener is Allulose (info above).


(Bang Energy) – For more information on Sucralose, read the article Is Sucralose Safe? The short answer is: yes, it’s safe and will not raise blood sugar. However, it’s not safe in baking (high heat) applications.

Donut and ChozZero CGM

Pumpkin Donut from cardnl – no impact to blood sugar (main sweetener is Erythritol & Monk Fruit).

ChocZero – so tasty (I really like the flavor) and I’ve tested it extensively over the last 2 years – However… I always get a spike (not terrible). I would not classify this product as Keto.

ChocZero CGM Fail

Here’s my CGM with ChocZero results from 16 months ago. Same results (different scenario). While it’s not a dramatic spike, it’s enough to advise those on a Keto diet and those searching for diabetic friendly chocolate to avoid.

ChocZero Keto Bark is not Keto Friendly

Smart Sweets ChocZero CGM Test

ChocZero claims to be Keto, it’s not. It tastes great but cannot be considered diabetic friendly OR ketogenic. If you are attempting to manage blood sugar, avoid these two products. I’ve tested them both extensively hoping to get a glucose flatline… it doesn’t happen (SmartSweets had one confounder to this but overall, negative results too). This was my last attempt with ChocZero – I consumed a dinner high in fat to see if it could normalize the response. Not even close. So what’s going on?

Resistant Malto(dextrin) Vs. Maltodextrin

ChocZero claims to use (Non-GMO Resistant Dextrin) Soluble Corn Fiber. I don’t know how this can be true, looking at my personal CGM results with the product. Let’s look at the details, to better understand:

Both ingredients are in-fact made from corn. Resistant maltodextrin (Dextrin) bypasses the normal digestive process. Typically, it will NOT create a glucose response in the blood. It’s generally considered to be a safe ingredient option for diabetic or keto diet management products.

Maltodextrin, on the other hand is one of the highest ranking glycemic ingredients, AKA – a HUGE spike to blood sugar. Read this post to compare on the glycemic index.

I don’t want to call out another brand (out of principle) but I feel compelled to do it. Choczero needs to either change their recipe or their Keto branding.


(cardnl Donut) – Erythritol is a sugar alcohol that does NOT raise blood sugar. About 90% of this sugar alcohol is excreted, unchanged in the urine. Erythritol is produced with enzymatic hydrolysis of the starch from corn to generate glucose. Glucose is then fermented with yeast or another fungus to produce erythritol.

Soluble Corn Fiber

As mentioned above, In theory: resistant dextrin will not spike blood sugar. SCF is made by heating it and adding acid to high-fructose corn syrup. It’s rendered down and “sugars” are removed. Be careful, mislabeling on this ingredient is plausible with some brands. Resistant Dextrin should generally be considered safe on a Keto diet. I need to do more personalized research on this ingredient.

Cheesecake Ice Cream CGM

cardnl Cheesecakes – for this I had a lot (all different flavors) – with no impact to blood sugar. The sweeteners used vary and include Erythritol and Allulose (both listed and described above).

Rebel Ice Cream – no glucose rise, main sweetener is Erythritol. One questionable ingredient is Chicory Root Fiber (though this is limited in this product).

Chicory Root Fiber

(in Rebel ice cream) /Inulin- Chicory root fiber is believed to be safe for diabetics and those on a Keto diet. It’s considered to be a sweetener that also helps to add “texture” to products. Chicory root comes from a plant with bright blue flowers that belongs to the dandelion family. I have no reason to believe this ingredient should be avoided on a Ketogenic diet.

Workout – slight rise in blood sugar (details below).

Sauna is known to raise blood sugar (details below).

SmartSweets – We removed all products from our store due to glucose spikes – they changed their recipe – lots to unpack here (see below).

Chipotle Bowl (Double chicken, queso, medium salsa, sour cream, cheese) – no impact.

Revol Snax

Ingredients: Organic Coconut, Almonds, Organic Erythritol, Chicory Root Fiber, Organic Coconut Oil, Organic Dark Cacao, Organic Cacao Powder, Organic Coconut Cream, Organic Coconut Flour, Vanilla, Sea Salt, Monk Fruit Extract

Blood Sugar & Working Out on Keto

If your glycogen stores are already depleted (in Ketosis), your body (when in need) will provide additional energy in the form of more Ketones and additional Glucose. This is especially true for me if I do a heavy workout or a HIIT workout. If I’m fasted/in Keto my body will provide me with additional glucose for output needs.

If you’re not fat adapted (eat excess carbs) you will likely see a decrease in blood sugar as you deplete glycogen stores. In this example, I was fasted and did a moderate workout. My glucose increased slightly to help with energy demand.

Why does the sauna raise blood sugar?

Hormones that oppose the action of insulin, such as growth hormone and glucagon, which have a hyperglycemic effect are partly to blame for raising blood sugar during a sauna session. It’s also reasonable to assume that excessive sweat (dehydration) may decrease blood volume which in turn increases blood glucose levels.

In this particular example, I finished fasting for 18 hours – I ate a large steak/butter and got right in to the sauna (after my workout too). Digestion (even though it was protein and fat) may have an added impact on blood sugar when sauna is involved.

Smart Sweets’ (NOT Keto Friendly)

I thought for a moment, Smart Sweets’ new recipe was going to be blood sugar friendly… I was wrong. First pic: old recipe, spike. Second pic, new recipe, no spike. Third pic, spike (with new recipe).

Why did the second pic (new recipe) not raise blood sugar? Prior to eating the Smart Sweets, I lifted weights, ate a steak, spent time in the sauna. This combination played a significant role in reducing my glycemic response. I will be doing more research on this.

SmatSweets Old Recipe CGM
Smart Sweets CGM Data

The first test here is my response to Smart Sweets after an energy drink, and a Keto drink (high fat). Blood sugar spike. No good.

Let’s look at the sweet ingredients in the new recipe:


(information listed above) – great alternative sweetener – does not raise blood sugar. Safe.

Isomaltooligosaccharide (IMO)

IMOs are typically derived from a sugar called maltose. Maltose is a malt sugar made from modified glucose. IMO’s are slow digesting carbohydrates. I would not classify this ingredient as a true fiber. I believe IMOs may under circumstances raise blood sugar.

Soluble Corn Fiber

See information listed above. The verdict is still out for me on this ingredient. It may have more of an impact due to quantity. We will never use this ingredient in any of our products (too many unknowns).

Tapioca Dextrin

I’d like to test this ingredient further. A hydrolyzed starch made from tapioca, tapioca dextrin is said to have a low glycemic impact, is derived from tapioca starch, and may be used in low-carb products. Verdict is still out on this.

Low overnight glucose on a Ketogenic Diet

It’s okay, no need to worry.

Here’s what my blood sugar typically looks like overnight. If I wasn’t fat adapted we’d see bigger peaks and valleys. Having blood sugar this low for some may prove dangerous. However, when you’re in ketosis, your body is creating ketones (for energy use) and having lower glucose levels is just fine.

Zevia Energy – as discussed previously, Stevia will not raise blood sugar. This product doesn’t use Reb M stevia (so there is a stevia taste). In fact, when I first had this product I didn’t like it… now I love it.

This CGM test is over a year old – I’ve tested Zevia on multiple occasions with no impact to blood sugar. Same meal at Chipotle too (mentioned above). That stable blood sugar line is common on a long-term low carb diet.

Costco Keto Bread

“Keto bread” found at Costco – not keto, raised blood sugar: AVOID. I tested this product 3 months ago. The very first ingredient is Tapioca Starch. This is most likely the main culprit for the rise.

Tapioca Starch (not Keto Friendly)

Different then Tapioca fiber, starch is not keto friendly. Tapioca is a starch extracted from the cassava root through a process of washing and pulping. The wet pulp is then squeezed to extract a starchy liquid. Once all the water evaporates from the starchy liquid, the tapioca flour remains. While I love cassava, it’s VERY high carb.

In circumstances like this, I wonder if the manufacturer (not a keto-centric company) just got things mixed up (Fiber v. Starch) dunno.

Space Shake Breakfast Panda CGM

Space Shake – high fat and no significant impact to blood sugar (sweetener: Stevia).

Keto and CO – hot breakfast – slight rise in blood sugar, sweetener: Erythritol (not responsible) soluble corn fiber (possible), inulin (possible), dried apple (probably too small of an amount to impact).

Panda Express – big spike

Panda Express Teriyaki Chicken and Veggies

In theory, this would be the best option for Keto at Panda Express but as you can see, it doesn’t pass the test. I wanted to highlight a “fast food” option – never a good idea. Sugar in sauce (even a small amount) – has a large impact. Most fast food includes added sugars. Living optimally: don’t eat fast food. Also, Panda Express uses soybean oil…

Is soybean oil bad?

New research shows soybean oil not only leads to obesity and diabetes, but could also affect neurological conditions like autism, Alzheimer’s disease, anxiety, and depression. Source

  • Inflammatory
  • Half linoleic acid – terrible at room temp and worse when heated.
  • A problem for managing Omega 6 and 3

Beware of “sugar-free” options & store bought beef jerky.

Wasabi Blue Diamond – Almonds are fine… the question is, what are they coated with? (more below)

Jack Links – Don’t trust beef jerky… this one had sugar added, slight raise. Moderately balanced with the protein.

Hershey’s Sugar Free Chocolate – Moderate rise – avoid (more below).

Blue Diamond Almonds

There is a small amount of sugar and maltodextrin. More on maltodextrin below. Products like this (mass production) tend to use the lowest cost oils (which are terrible) – soy and canola oils should be avoided (more on that below).

Is Maltodextrin bad?

YES. Maltodextrin is believed to be a terrible alternative ingredient to add sweetness. It’s cheaper than the alternatives but is believed to cause blood sugar spikes and contribute to insulin resistance. Read this rat study. Maltodextrin is NOT Keto friendly nor is it a good alternative ingredient to promote insulin sensitivity.

Why is canola oil bad?

Yes. The reason people think it’s a good alternative goes back to the war against saturated fats. To be clear, canola is low in saturated fat. To be clear, saturated fat is GOOD.

YES – Margarin is REALLY BAD. YES – anything cooked in canola oil is BAD.

Fatty Acid Composition:

  • Saturated fat: 7%
  • Monounsaturated fat: 64%
  • Polyunsaturated fat: 28%

Here are a few reasons why you should avoid Canola oil:

  • High Glyphosate levels (weed killer)
  • Full of chemical solvents
  • High in trans fats (heart disease, obesity, memory loss)
  • Heart Disease (Studies have identified that the trans-fatty acids created in the hydrogenation process cause inflammation and the calcification of arterial cells) study
  • Inflammation (linoleic acid – pro-inflammatory and thrombogenic properties)

Why should I avoid products with soy?

Soy contains isoflavones (mimic estrogen) and goitrogens (inhibit the thyroid’s ability to utilize iodine correctly). Soy also contains a variety of nutrient blockers which make it difficult for your body to absorb various nutrients.

Jerky typically has sugar unless the label specifically states sugar free. Not a significant rise but with the wrong combination, you’ll feel it. Avoid.

Hershey’s Sugar-Free Chocolate

How can some keto chocolate be so expensive and Hershey’s be so cheap? Two reasons: mass production vs. small batch. And the bigger culprit, ingredients. Ingredient #1 in Hershey’s chocolate is Maltitol. And it doesn’t get any better after that… here’s what the ingredients are: Maltitol, Cocoa Butter, Chocolate*, Polydextrose, Cream Milk*, Polyglycitol, Milk Fat, Contains 2% or Less of: Calcium Carbonate, Cocoa Processed with Alkali*, Maltodextrin, Sodium Caseinate (Milk), Lecithin (Soy), Natural Flavor and Artificial Flavor, PGPR, Emulsifier.

What’s the problem with Maltitol?

If you like consuming sugar alcohols with a glucose spike, Maltitol is just right for you. On the glycemic index, Maltitol scores a 35 (which is high – learn more about glycemic index for sweeteners in this post). Maltitol is not a Keto friendly ingredient.

Eating an entire pint of Killer Creamery ice cream

Okay, so this is a little bit much BUT… No glucose spike. Do I recommend eating a pint of ice cream? No. Did it raise my blood sugar? Nope. Was it good? Oh yeah.

Of course, eggs, steak, and butter don’t impact blood sugar. AND neither did an entire pint of Keto ice cream.

Sweet ingredients: Allulose (info above), Soluble Corn Fiber (info above), Erythritol (info above), Monk Fruit.

Monk Fruit

Monk fruit gets a ZERO on the glycemic index (which means there will NOT be a spike with blood sugar). That’s great news. Monk Fruit is added to a lot of keto treats but is never a large amount of the product (not much is used), in fact it’s typically the last ingredient (smallest amount). By itself, it’s not tasty. But it does add just the right amount of sweet flavor (in very small quantities). Monk Fruit gets an A+ from me.

Rebbl Drink, Reign Energy, Smart Sweets (again)

Rebbl Reign Energy Smart-Sweets CGM

Sucralose (in Reign) does nothing to blood sugar. Here’s the article again if you missed it, Is Sucralose Safe?

Rebbl is heavy, filling, and does NOT impact blood sugar: safe.

SmartSweets – that’s going to be a no from me, dog. The new blend IS NOT safe if you’re trying to avoid blood sugar spikes. More information above.

Bhu Bars Glucose Response

Disclaimer: This test was performed on a new CGM that was reading higher than my baseline finger prick (happens on occasion with a new sensor for me) – 1 in every 4 (on average).

I really like the taste of Bhu Bars, there was a slight spike (with 2 bars) – this isn’t terrible but I wouldn’t advise eating these regularly if you’re trying to manage diabetes or are on a therapeutic ketogenic diet.

What’s causing the Blood Sugar response?

I’ll start off by explaining that I’m not a fan of fiber ingredients on packaged goods (to add sweetness in low carb snacks) – they’re tricky and difficult to really know if they’ll impact blood sugar or not (lots of gray area). Another large drawback is they almost always cause stomach discomfort.

The ingredient that may be the culprit for a slight bump in blood sugar response is

Prebiotic Fiber from Tapioca (possible issue: IMO)

There’s a lot of information on tapioca fiber and starch listed above. Tapioca fiber should be just fine, starch is a no go (on a low carb diet). However, if it spikes blood sugar – buyer beware. Let’s discuss what might be happening here. Often, products are mislabeled and actually include isomaltooligosaccharides (like mentioned above – IMO). I’m not accusing Bhu – but if there’s a blood sugar response, there has to be a cause. IMOs are not a true fiber. IMO is a 35 on the glycemic index. Many companies hide this in ingredients labeled:

  • Prebiotic Fiber (Corn/Tapioca)Vegetable
  • Fiber (Corn/Tapioca)
  • Soluble Tapioca Fiber
  • Soluble Corn Fiber

Fibers listed on a package – just beware, there might be an issue. You may not want to risk all of your hard work consuming sweet products, protein bars, etc with any of the ingredients listed above.

I’ll continue to carry Bhu Bars at cardnl, I think they fill a gap, they taste good, and they’re not causing a huge impact to blood sugar. However, if you’re therapeutically trying to reverse diabetes, manage type 1, or are on a ketogenic diet to reverse metabolic disease, maybe you should avoid them.

The Ideal Break-Fast

Steak is an absolute MUST. More on that here. Click the link to learn about all of the benefits of eating beef everyday.

+ Electrolytes. Total game changer. Reb M Stevia – no calories, no impact to fasting or blood sugar.

Strawberry Lime Nut Butter

Ingredients: Blanched Roasted Almonds, Cocoa Butter, MCTs, Erythritol, Strawberries, Redmond Real Salt, Stevia, Lime Oil

Oats (will raise blood sugar) – However, it’s reduced with the addition of a lot of fat (in this case, heavy cream).

Always adding more (check back often)

Save this image (below) on pinterest.

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Monday 24th of May 2021

If we can’t get a CGM, is it possible to test blood like we would if diabetic? I have a monitor from pregnancy when I had to test during gestational diabetes.

Also - Built bars?


Rob Benson

Monday 24th of May 2021

Absolutely, it just gets annoying having to prick your finger every time you want to check.

I've never had a Built Bar... not a big fan of protein bars (here's one product's ingredient list foor example: Protein mix (whey protein isolate[milk], partially hydrolyzed whey protein isolate[milk]), gelatin, dark chocolate (chocolate liquor, sugar, cocoa butter, lecithin, vanillin [a natural flavor]), water, erythritol, glycerin, maltodextrin, natural coconut flavor, citric acid.)

The problems (for blood sugar) are: sugar and maltodextrin - BUT they are probably not even half a percent of the overall ingredient profile. I doubt this particular Built Bar would raise blood sugar. Without trying it, I would say it's safe (doesn't significantly raise blood sugar).


Saturday 15th of May 2021

Wow! This was so informative!! Thank you!!! What are your thoughts on Quest bars/cookies?

Rob Benson

Monday 17th of May 2021

Welcome! And thank you.

Some of the Quest products use Sucralose (which I have no problem with) UNLESS it's heated... I need to revisit Quest again. Thank you for asking. :)

David McCaman

Sunday 18th of April 2021

Rob - good job in helping others visualize how a CGM can assist with cutting through stories about healthy foods to instead reveal the exact impact on the wearer's body (yours in this case). I didn't catch the details of which CGM you use, and which service (if any) as there are several available these days. I think it's useful to point out where people who are curious can further explore these valuable devices and related services.


Rob Benson

Monday 19th of April 2021

Thanks, Dave!

I use the Freestyle Libre. I'm not sure of the best services to get this currently. None have reached out to me and I don't have any preference currently.

Hopefully soon I can be more helpful on recommendations.

Michael DeLeon

Tuesday 6th of April 2021

I’ve learned a lot from this article and appreciate the time you have taken to test these different products out! Look forward to reading more as they come!

Rob Benson

Thursday 8th of April 2021

Thanks, Michael.

Alison Francone

Wednesday 24th of March 2021

This article is one of the best treatments I've seen on this complex topic, and so cool that it's based on your ACTUAL experience! I have been debating getting a CGM for at least short term use but haven't based on the cost. This was extremely valuable and informative. Knew SmartSweets weren't cutting it for me! LOL. Thank you!

Rob Benson

Wednesday 24th of March 2021

You're so welcome. And thank you for your thoughts! Go for the CGM however you can. You'll learn more about your diet and lifestyle from that data than any nutritionist or doctor could ever diagnose (in relation to blood sugar). :)