Ultimate Guide to Low-Carb Sweeteners: the Safe, the Nasty, and the Scary

Do you have a sweet tooth? So do I. Thank God for low-carb sweeteners, right?!

But the world of alternative “sugars” is a confusing kaleidoscope of options: some are safe and even beneficial, while others have nasty consequences.

This ultimate guide will help you choose your low-carb sweeteners with confidence!

Low-Carb Sweeteners

Acesulfame Potassium: Ace-K & Sunette

This sweetener is widely used in low-carb/keto protein bars and shakes as well as Coca-Cola Zero Sugar.

On the plus side, acesulfame potassium is not fully absorbed by the gut, is calorie-free, carb-free, and doesn’t raise blood sugar.

It does have a slightly bitter flavor however, so it’s often combined with aspartame to improve the taste.

Now for the bad stuff.

Studies show that acesulfame potassium raises insulin just as much as if you’d eaten an equivalent amount of pure sugar (glucose)!

It seems to work directly on the pancreas to stimulate insulin release. This is exactly what you don’t want if you’re trying to lose weight.

Dr. Adam Nally, author of The Keto Cure, comments that in his medical practice, he has found that acesulfame potassium significantly limits weight loss and raises both triglycerides and small-dense LDL particles (the bad cholesterol).

Run–don’t walk–to another sweetener!

The verdict: SCARY

Aspartame: NutraSweet & Equal

This one has been used as a food additive since the FDA approved it in 1981. It has zero calories and zero carbs.

The liquid form of aspartame does not appear to disrupt ketosis.

But it’s not heat-stable or shelf-stable. Over time, or when it’s rapidly heated, it breaks down into its chemical components (creating a sour or metallic flavor).

Many people use liquid aspartame without notable ill effects, but others report headaches, stomach upset, migraines, and worsening of depression.

Aspartame can be converted into a powder by bonding it to dextrose or maltodextrin (sugars that spike insulin).

If you look at the ingredients on a packet of Equal, you’ll see maltodextrin as the #1 ingredient, followed by aspartame and acesulfame potassium (see above).

These additives raise insulin, cause weight gain and inflammation, and increase the risk of diabetes.

One animal study found that prolonged exposure to a by-product of aspartame metabolism caused damage to the mitochondria of brain cells, leading to brain cell death.

Yes, aspartame can kill brain cells. I don’t know about you, but I just don’t have any neurons to spare.

The verdict: TWO THUMBS DOWN

Sucralose: Splenda

Sucralose contains both calories and carbohydrates, though far less than sugar. It has a long shelf life and is heat-stable (useful for baking). It was approved by the FDA as a food additive in 1998.

But what is sucralose, exactly?

Well, it’s made by chemically converting sugar into a form that the body doesn’t recognize and can’t absorb.

(The pure liquid form is created by replacing three hydrogen-oxygen groups on the sugar molecule with three chlorine atoms.)

Sucralose turns into crystals when bound with dextrose or maltodextrin, both of which are sugars.

In fact, Splenda contains 95% bulking agents (dextrose and maltodextrin) by volume.

So sucralose products aren’t carb-free, but they only contain only about 1/8th the carbohydrates of pure sugar, which is 12-15 carbs per cup.

Sucralose also stimulates insulin release. This is another one that Dr. Nally reports causes weight gain in his patients when used excessively.

Animal studies indicate that sucralose may damage beneficial gut bacteria, although I haven’t read of any parallel studies in humans.

But I do know that in humans, a loss of intestinal probiotics tends to cause problems like Irritable Bowel Syndrome.

So I suggest giving sucralose a miss. (Psst! Did you know there’s a low-carb sweetener that actually nourishes your gut probiotics?! Keep reading…)

The verdict: THUMBS DOWN

Saccharine: Sweet’N Low & SugarTwin

Dr. Nally’s book says that saccharine is a chemical that is not heat-stable, but Wikipedia claims that it is (although they don’t have a citation to back that up).

But everybody agrees that it’s shelf-stable. In fact, it’s often combined with other sweeteners to improve the shelf life of food products.

Saccharine doesn’t raise blood sugar, but it does stimulate an insulin response and is therefore not useful for weight loss.

The verdict: THUMBS DOWN

Cyclamate: SugarTwin & Sucaryl

This one is similar to sucralose and is often combined with saccharine. It’s heat-stable and useful for cooking and baking — if you live in Canada.

Cyclamate is banned in the US because it’s been shown to cause bladder cancer in lab rats, although there’s been no incidence of the same in humans during the 30 years it’s been in use.

The verdict: NOT ENOUGH DATA

Allulose: All-u-Lose

This is an interesting new product.

Also called D-psicose and D-allulose, it’s a monosaccharide (single molecule sugar structure) derived from raisins, wheat and/or figs.

It’s lower in calories than sugar and only 70% as sweet as sugar, but has a similar taste and texture.

The FDA currently has it designated as GRAS (a substance generally regarded as safe).

Studies to date have not shown a rise in glucose or insulin levels in animals, although apparently in humans there is an insulin spike 15 minutes after eating it.

Human tests with amounts up to 1 tablespoon per day showed no negative side effects.

There were some positive effects as well: better blood sugar control, reduced risk of diabetes, some appetite-suppressing effects, and a slowing of weight gain (does that mean people still gained weight with it? I don’t know).

Research on this sweetener is still fairly limited. It’s also about twice as expensive as erythritol (ouch).

The verdict: NOT ENOUGH DATA

Monk Fruit (Luo Han Guo): Enlight & PureMonk

Also known as Buddha fruit, this is one of the newest sweeteners to hit the market.

It’s extracted from a melon-like gourd that has traditionally been used in Asia as a folk remedy.

It’s also heat-stable and doesn’t raise blood sugar.

Now for the bad news: it does raise insulin.

People who are more insulin-resistant may find that consuming monk fruit sweeteners will drop them out of ketosis and halt their weight loss.

So it works fine for some folks (who aren’t insulin-resistant) but not for others.

If you’re having trouble losing the pounds, try losing the monk fruit instead.

The verdict: YOU CAN DO BETTER

Sugar Alcohols: Truvia & Swerve

We’ve been hearing about these since the days of Atkins. What the heck are sugar alcohols?

As you’ve probably guessed, they’re neither sugar nor alcohol (who’s in charge of naming these things?)

They’re actually a type of long-chain carbohydrates that are not fully absorbed in the human intestines.

This causes the side effect for which they are infamous: gas and bloating.

Maltitol, sorbitol, and xylitol seem to be the most problematic. They cause half as much of an insulin response as pure sugar!

People’s bodies vary in their ability to absorb these sugar alcohols, but what’s clear is that they do raise blood sugar and insulin.

The worst news is that maltitol and sorbitol have been found to increase cholesterol levels.

But wait!

Erythritol is the only sugar alcohol that passes right through your body without impacting blood sugar or insulin levels.

It reportedly causes less digestive upset than the others (your mileage may vary).

Erythritol also seems to have an inhibiting effect on fructose absorption (not that you were going to be eating fructose on keto anyway).

The only real downside to erythritol is the odd cooling sensation you feel on your tongue.

It’s like chewing mint gum without the mint.

Some folks find it unsuitable for use in high concentrations (like fudge or frosting).

But in baking, I think we can all agree that it’s brilliant.

It provides volume as well as sweetness, unlike some other low-carb sweeteners.

Swerve is a combination of erythritol and FOS (see below).

Truvia combines erythritol and stevia (see below). In clinical trials with this product, the subjects’ blood sugar and insulin levels were unaffected.

(But stay away from the Truvia Baking Blend because it contains sugar in the form of maltodextrin.)

The verdict: THUMBS UP for erythritol, THUMBS DOWN for the rest

Stevia: SweetLeaf & Pyure

The pure liquid extract, without additives, is zero-calorie and zero-carb.

Stevia does not increase blood sugar and it appears to actually improve insulin sensitivity in the pancreas!

This sweetener is derived from the garden herb Stevia rebaudiana, which is native to South America.

You can grow it yourself — many garden stores sell it in pots — but maybe don’t tell your kids.

I tried growing a stevia plant one year, but it did not survive its first encounter with my toddler, who happily picked and ate all the leaves in one sitting.

You can get dried stevia leaves whole or powdered from an herbal supplier like Frontier or Mountain Rose Herbs.

Once you figure out how sweet you like your cuppa, you can just mix the leaves right into a whole container of your favorite loose-leaf tea.

Then whenever you brew up a teapot, your drink will be pre-sweetened.

Green stevia does have a noticeable herbal flavor with a hint of licorice, so I think it goes best in herbal teas.

Watch out with the green powder version, though.

I find that it’s easy to add too much, which makes my beverage sweet to the point of nastiness with a slightly bitter aftertaste.

Refined stevia (without the herbal flavor) is available as a clear liquid or white powder.

Read the ingredients because some brands of powdered stevia include sugars (dextrose or maltodextrin) as bulking agents.

Stevia is heat-stable, but baking with it requires a specially designed recipe because stevia does not contribute to the volume of baked goods the way sugar does.

Once you’ve got a good recipe though, you can make fabulous low-carb cheesecakes and muffins.

When I need white stevia powder, I use SweetLeaf brand because it contains only stevia extract and inulin fiber (see below).

It also has no aftertaste. Dissolves well in hot beverages but not in cold ones.

I buy SweetLeaf liquid stevia pretty much constantly because it goes perfectly in every beverage from my morning latte to my evening keto cocktail.

It also comes in delicious flavors like English toffee, orange, berry, and root beer (my kids love it in sparkling water).

The company did not even pay me to rave about their products. But they really should.

The verdict: THUMBS UP!

FOS: Swerve

You may have heard of “inulin fiber” — perhaps you’ve seen it on the list of ingredients in various low-carb sweetener products?

Fructooligosaccharides (FOS) is the technical term.

FOS is derived from plant sources such as green bananas, onions, garlic, blue agave, and chicory root, and is about 35% as sweet as sugar.

What is it?

FOS is a type of water-soluble fiber that you can’t digest, which means it’s calorie-free.

It also doesn’t raise blood sugar and doesn’t affect insulin levels. Jackpot!

As an added bonus, this indigestible fiber nourishes your beneficial gut bacteria (which is why it’s sometimes called a prebiotic: it feeds your probiotic helpers).

Swerve is a mixture of FOS and erythritol (see above).

The verdict: THUMBS UP!

Making your best choice

Now that you’re an expert on low-carb sweeteners, you can choose the ones that  meet your needs for baking, hot or cold beverages, and everything else.

We all love tasty sweets, and that’s why having safe, delicious low-carb sweeteners in your cupboard is essential to your keto success.

Do you need a mouth-watering recipe for keto-friendly desserts, fat bombs, or cocktails?

Grab your favorite low-carb sweetener and whip up a sweet treat!