Low-carb sweeteners, the best and the worst

What sweeteners can you use on a low-carb diet? Check out the visual guide below. The sweeteners to the left are very low in carbs and have generally been shown to have little impact on  blood sugar and insulin levels.1 The sweeteners to the right, in the red zone, should be avoided.

Keto sweeteners


The numbers above are based on the effect each sweetener has on blood sugar and insulin response, for an equal amount of sweetness compared to white sugar (100% pure sugar). Keep in mind that many sweetener packets contain a small amount of dextrose, which is pure sugar.2

If you’re aiming to stay low carb, try to avoid the sweeteners to the right in the picture above. The best options are to the left. We suggest primarily using , or .

Negative effects of all sweeteners

Note that while the sweeteners to the left above have minimal direct effects on blood sugar and insulin levels, they may still have other potential negative effects.

All sweeteners can maintain cravings for sweet foods.3 Also, when added to foods – such as muffins or yogurt – they may result in a significantly increased feeling of reward when eating. So by adding sweeteners to your foods you’re increasing the risk that you’ll end up eating more than you need. This can slow down weight loss, or cause weight gain.

The question marks by the sweeteners labeled as “zero” indicate that although they appear to have no effects on blood glucose and insulin, their impact on obesity, diabetes, gut health, and long-term risk for metabolic or cardiovascular disease is not yet known. More research is needed.4

This means that all sweeteners, including the non-caloric ones above, may have potentially negative effects. If you’re able to, you may be better off just avoiding all of them. Note that on a low-carb diet cravings for sugary foods tend to decrease over time, making it easier and easier to avoid them.5

However, most people enjoy something sweet once in a while. If this is true for you, we suggest trying to do it only occasionally. Keep reading to learn more, including how to make better-informed choices.

Using sugar as a sweetener


Note that many sweeteners – white or brown sugar, maple syrup, coconut sugar and dates – have a number of exactly 100. This is because these sweeteners are made up of sugar. Sugar is also known as sucrose, which is 50% glucose and 50% fructose. To get the same amount of sweetness as white sugar, these sweeteners will have a similar effect on blood sugar, weight and insulin resistance.6

Sugar is potentially harmful for your health, no surprise, so these are all likely not ideal options, especially if you’re on a low-carb diet. Avoid.

Even worse than sugar: fructose

Amazingly, there are sweeteners that may be even more problematic than sugar in the long run. Regular sugar contains 50% glucose and 50% fructose. However, some sweeteners contain more fructose than glucose. These sweeteners are slower to raise blood glucose, resulting in a deceptively low glycemic index (GI), a measure of how quickly a carbohydrate-containing food results in a blood sugar increase after eating it. Yet they may have even more potentially harmful effects.

Consuming excessive fructose can increase the likelihood of developing fatty liver and insulin resistance, increasing the risk of weight gain and future health problems.7


These sweeteners with excess fructose – high fructose corn syrup (soda), fruit juice concentrate, honey and agave syrup – might have a slightly worse long-term effect than pure sugar. Thus we give them a number of 100+. Which sweetener has the highest fructose content of all? Agave syrup.

This is not to say that sugar is good. Clearly, sugar is potentially harmful to our metabolic health. Sugar as well as these high-fructose sweeteners are not good options on a low-carb diet.


Our recommendations

As stated above, all sweeteners have potential negative effects. However, some are less problematic than others. Here are our top 4 suggestions:

Not-too-bad option #1: Stevia

SteviaStevia comes from the Stevia rebaudiana plant, which is native to South America, where it has been used for several hundred years. Steviol glycosides extracted from the plant are responsible for its sweet taste.

  • Stevia doesn’t contain carbs or calories and does not raise blood sugar levels.8
  • Stevia appears to be safe and nontoxic.9
  • Stevia doesn’t really taste like sugar. It has a licorice-like flavor and an undeniable aftertaste when used in moderate to large mounts. Therefore, using it sparingly is recommended.
  • There’s not enough long-term data on stevia to be certain of its true impact on the health of frequent users.10

Sweetness: 200-350 times sweeter than table sugar.

Best choices: Liquid stevia or 100% pure powdered or granulated stevia. Note that some packets of granulated stevia such as Stevia in the Raw contain the sugar dextrose. The brand Truvia contains added erythritol (see below) but no dextrose.

Not-too-bad option #2: Erythritol

ErythritolErythritol is a sugar alcohol, a compound that resembles sugar but is only partially digested and absorbed by the body. Erythritol occurs naturally in plants like grapes, melons, and mushrooms in small amounts. However, as a commercial sweetener, it is usually made from fermented corn or cornstarch.

  • Erythritol does not raise blood sugar or insulin levels.11
  • It provides nearly zero calories and is virtually carb-free. After being absorbed, it passes into the urine without being used by the body.12
  • Erythritol might be helpful in preventing dental plaque and cavities, compared to other sweeteners.13
  • Erythritol has a noticeable cooling sensation on the tongue, particularly when used in large amounts.
  • Although it causes fewer digestive issues than most sugar alcohols, some people have reported bloating, gas and loose stools after consuming erythritol.
  • While absorbing erythritol into the blood and excreting it into the urine appears to be safe, there may be some potential for unknown health risks. Longer studies are needed to know for sure.

Sweetness: 70% as sweet as table sugar.

Best choices: Organic granulated erythritol or erythritol and stevia blends.

Not-too-bad option #3: Monk fruit

Although it’s derived from a round, green fruit grown for centuries in Southeast Asia, monk fruit is a relatively new sugar substitute on the market. Also called luo han guo, monk fruit is traditionally dried and used in herbal teas, soups and broths in Asian medicine. It was cultivated by monks in Northern Thailand and Southern China, hence its more popular name.

While the fruit in whole form contains fructose and sucrose, it also contains non-caloric compounds called mogrosides that are intensely sweet, estimated to be up to 200 times as sweet as sugar. In 1995, Proctor & Gamble patented a method of solvent extraction of the mogrosides from monk fruit.

Monk fruit is often mixed with stevia to reduce cost and blunt stevia’s aftertaste. Similarly, it is often mixed with erythritol to reduce cost and improve its suitability for baking.

While the US FDA has not ruled on monk fruit as GRAS (generally regarded as safe), it has publicly noted that it accepts manufacturers’ GRAS determination. In the last few years more than 500 monk fruit products have come to market in the US. Monk fruit has not yet been accepted for sale by the European Union, but approval appears to be pending.

  • It is calorie-free and does not raise blood sugar levels.14
  • It has a better taste profile than many other sweeteners, with minimal aftertaste.
  • It doesn’t cause digestive upset.
  • It is expensive.
  • It is often mixed with other “fillers” like inulin, prebiotic fibres and other undeclared ingredients.
  • Be careful of labels that say “propriety blend,” as these products may have little active mogroside ingredients.
  • It is very new, and there aren’t any studies on its long-term effects.

Sweetness: 150-200 times sweeter than table sugar.

Products: Granulated mixes with erythritol or stevia, pure liquid drops, or liquid drops with stevia; also used in replacement products like monkfruit-sweetened artificial maple syrup and chocolate syrup.

Not-too-bad option #4: Xylitol

XylitolLike erythritol, xylitol is a sugar alcohol found in fruits and vegetables in small amounts. It is produced commercially from corn cobs or birch trees. Xylitol is one of the most frequently used sweeteners in sugar-free chewing gum and mouthwash.

Note however, that xylitol is only low carb, not zero carb. So it’s not a perfect choice on a keto diet (below 20 grams per day). The carbs can quickly start to add up.

  • Xylitol has a low glycemic index of 13, and only 50% is absorbed in the digestive tract.15 When used in small amounts, this results in a very minor impact on blood sugar and insulin levels.16
  • Although it tastes like sugar and has a level of sweetness identical to table sugar, xylitol contains 2.5 calories per gram, whereas sugar provides 4 calories per gram.
  • Like erythritol, it’s been shown to help prevent cavities, compared to other sweeteners.17
  • Because 50% of xylitol is not absorbed but instead fermented by bacteria in your colon, it may cause digestive issues (gas, bloating, etc.) when consumed in moderate to large amounts.18
  • Although xylitol is safe for humans, it is toxic and potentially lethal for pets, like cats and dogs. If you use xylitol, make sure to keep it away from your animals.

Sweetness: Equivalent in sweetness to table sugar.

Best choices: Organic granulated xylitol made from birch.


The “zero-calorie” sweeteners that are almost 100% carbs

Artificial sweeteners

Packets of Stevia in the Raw, Equal, Sweet’n Low and Splenda are labeled “zero calories,” but this is just a trick. FDA rules allow products with less than 1 gram of carbs and 4 calories per serving to be labeled “zero calories.” So  manufacturers cleverly add about 0.9 grams of pure carbs (glucose/dextrose) – the filling agent that makes up almost 100% of the sweetener – mixed with a small dose of a more powerful artificial sweetener, for added sweetness.

Voilà — a sweetener packet full of carbs that can be labeled “zero calories” without risking a lawsuit.

The packets in fact contain almost 4 calories each, and almost a gram of carbs. While 0.9 grams of carbs may seem negligible for many people, on a low-carb diet it can matter — especially if you use many packets a day. Ten packets equals 9 grams of carbs, which is almost half the daily carb limit on a keto diet.

So at least be aware of this. We don’t recommend these sweeteners because of the deceptive marketing. There are also lingering potential health concerns with many of these artificial sweeteners, including aspartame and sucralose.19

Why maltitol is not a good option

Maltitol is the most common type of sugar alcohol used in “sugar-free” candy, desserts, and low-carb products because it’s considerably less expensive than erythritol, xylitol, and other sugar alcohols.

Maltitol is not a good choice for people on low-carb diets. About 40% of this sweetener is absorbed in the small intestine, which can raise blood sugar and insulin levels, especially in those with diabetes or prediabetes.20 It also provides about three-quarters as many calories as sugar, which is considerably more than most low-carb sweeteners.21

In addition, the roughly 60% that’s not absorbed is fermented in the colon. Studies have shown that maltitol may cause significant gastrointestinal symptoms (gas, bloating, diarrhea, etc.), especially when consumed in large amounts.22

Sweetness: About 80% of the sweetness of table sugar.

Diet soft drinks – yes or no?

Diet sodasCan you drink diet soft drinks on a low-carb diet? Ideally, you may want to avoid them. For some people, regular consumption can stimulate cravings for sweet foods and prevent retraining your palate to enjoy the natural taste of unsweetened drinks.

There’s also science suggesting that diet beverages may make it harder to lose weight, despite containing no calories.23

There are also other suspected, but unproven, health concerns with many of the artificial sweeteners commonly used in diet sodas and other beverages.24

However, if you feel you absolutely need to drink diet sodas, at least they will allow you to stay low carb. Regular soda, sweetened with sugar or HFCS, will very quickly result in a high carb intake, negating the positive effects of a low-carb diet.

A final word on low-carb sweeteners

While some sweeteners seem to be better than others, the best strategy for achieving optimal health and weight loss may be learning to enjoy real foods in their unsweetened state.

Although it might take a little time for your tastebuds to adapt, over time, you may discover a whole new appreciation for the subtle sweetness of natural, unprocessed foods.

Sugar addiction

Do you find it almost impossible to consider giving up sweet foods? You can do it. Here’s something that may interest you: our course on sugar addiction and how to take back control.

Similar low-carb guides

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  1. A large review of 46 controlled trials found that aspartame, saccharin, stevia, and sucralose had minimal to no effect on blood sugar and insulin response:

    Physiology & Behavior 2017: Do non-nutritive sweeteners influence acute glucose homeostasis in humans? A systematic review [systematic review of controlled trials; strong evidence]

    An RCT in both lean and obese adults found that the sugar alcohols erythritol and xylitol had minimal to no effect on blood sugar and insulin levels:

    American Journal of Physiology, Endocrinology & Metabolism 2016: Gut hormone secretion, gastric emptying, and glycemic responses to erythritol and xylitol in lean and obese subjects [randomized controlled trial; moderate evidence]

  2. For example, a packet of Splenda provides about the same sweetness as two teaspoons of sugar, or 8 grams of sugar.

    Each packet contains about 0.9 grams of carbohydrate from dextrose. That’s 0.9 / 8 = 0.11 times the effect of sugar, for an equal amount of sweetness.

    Pure 100% sugar has a number of 100, so Splenda gets a number of 100 x 0.11 = 11.

  3. Research suggests that in some people, sugar substitutes may partially activate the “food reward” pathway responsible for cravings:

    The Yale Journal of Biology and Medicine 2010: Gain weight by “going diet?” Artificial sweeteners and the neurobiology of sugar cravings [overview article; ungraded]

  4. Here are three recent reviews showing that questions remain about the long-term effects of artificial sweeteners:

    Canadian Medical Association Journal 2017: Nonnutritive sweeteners and cardiometabolic health: a systematic review and meta-analysis of randomized controlled trials and prospective cohort studies [systematic review; strong evidence for lack of benefit for weight loss or health]

    Obesity 2018: Nonnutritive sweeteners in weight management and chronic disease: a review [overview article; ungraded]

    PLoS Medicine 2017: Artificially sweetened beverages and the response to the global obesity crisis [overview article; ungraded]

  5. This is mainly based on clinical experience of low-carb practitioners.[weak evidence]

  6. For instance, coconut sugar is about 70-80% sucrose (table sugar), with the remainder coming from glucose and fructose:

    British Dental Journal 2017: Alternative sugars: Coconut sugar [overview article; ungraded]

    Studies have shown that even small to moderate amounts of sugar can promote inflammation and other negative metabolic effects:

    American Journal of Clinical Nutrition 2011: Low to moderate sugar-sweetened beverage consumption impairs glucose and lipid metabolism and promotes inflammation in healthy young men: a randomized controlled trial [moderate evidence]

    Journal of Nutrition 2015: Consumption of honey, sucrose, and high-fructose corn syrup produces similar metabolic effects in glucose-tolerant and -intolerant individuals [randomized crossover trial; moderate evidence]

  7. In studies, overweight and obese adults who consumed high-fructose beverages for 10 weeks gained weight and experienced a worsening of insulin resistance and heart disease risk factors:

    The Journal of Clinical Investigation 2009: Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans [randomized controlled trial; moderate evidence]

    European Journal of Clinical Nutrition 2012: Consumption of fructose-sweetened beverages for 10 weeks reduces net fat oxidation and energy expenditure in overweight/obese men and women [randomized controlled trial; moderate evidence]

    Some, although not all, reviews on dietary fructose conclude that consuming it on a regular basis may lead to metabolic health issues:

    Nutrition and Metabolism 2005: Fructose, insulin resistance, and metabolic dyslipidemia [overview article; ungraded evidence]

    Nutrients 2017: Fructose consumption, lipogenesis, and non-alcoholic fatty liver disease [overview article; ungraded evidence]

  8. This has been shown in studies of both lean and obese adults:

    International Journal of Obesity 2017: Effects of aspartame-, monk fruit-, stevia- and sucrose-sweetened beverages on postprandial glucose, insulin and energy intake [randomized controlled trial; moderate evidence]

    Appetite 2010: Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels [randomized controlled trial; moderate evidence]

  9. Journal of Nutrition 2018: Stevia leaf to stevia sweetener: exploring its science, benefits, and future potential [overview article; ungraded evidence]

  10. Obesity (Silver Spring) 2018: Non-nutritive sweeteners in weight management and chronic disease: a review [overview article; ungraded evidence]

    At least one study shows that large amounts of stevia may increase insulin secretion, which could potentially drive fat storage and metabolic issues:

    Metabolism 2004: Antihyperglycemic effects of stevioside in type 2 diabetic subjects [randomized controlled trial; moderate evidence]

  11. American Journal of Physiology, Endocrinology & Metabolism 2016: Gut hormone secretion, gastric emptying, and glycemic responses to erythritol and xylitol in lean and obese subjects [randomized controlled trial; moderate evidence]

  12. Regulatory Toxicology and Pharmacology 1996: Erythritol: a review of biological and toxicological studies [overview article; ungraded evidence]

  13. International Journal of Dentistry 2016: Erythritol is more effective than xylitol and sorbitol in managing oral health endpoints [review article; ungraded]

  14. International Journal of Obesity 2017: Effects of aspartame-, monk fruit-, stevia- and sucrose-sweetened beverages on postprandial glucose, insulin and energy intake [randomized controlled trial; moderate evidence]

  15. Nutrition Research Reviews 2003: Health potential of polyols as sugar replacers, with emphasis on low glycemic properties [overview article; ungraded]

  16. American Journal of Physiology, Endocrinology & Metabolism 2016: Gut hormone secretion, gastric emptying, and glycemic responses to erythritol and xylitol in lean and obese subjects [randomized controlled trial; moderate evidence]

  17. Journal of Natural Science, Biology, and Medicine 2017: Xylitol in preventing dental caries: a systematic review and meta-analyses [strong evidence]

  18. European Journal of Clinical Nutrition 2007: Gastrointestinal tolerance of erythritol and xylitol ingested in a liquid [randomized trial; moderate evidence]

    Although this is presumably related to xylitol being partially fermented in the colon, some research suggests that xylitol might also lead to adverse changes in gut bacteria:

    Caries Research 2019: Oral and systemic effects of xylitol consumption [overview article; ungraded evidence]

  19. These concerns, which include changes in gut bacteria composition and increased inflammation, are mainly based on the results of animal experiments and also a few human trials:

    Nutrition Reviews 2017: Revisiting the safety of aspartame [overview article; ungraded]

    Advances in Nutrition 2019: Effects of sweeteners on the gut microbiota: a review of experimental studies and clinical trials [overview article; ungraded]

    Frontiers in Physiology 2017: Gut microbiome response to sucralose and its potential role in inducing liver inflammation in mice [mouse study; very weak evidence]

  20. Maltitol has the highest glycemic index (35) and insulin index (27) of all the sugar alcohols:

    Nutrition Research Reviews 2003: Health potential of polyols as sugar replacers, with emphasis on low glycaemic properties [overview article; ungraded evidence]

  21. Maltitol contains 3 calories per gram, and sugar contains 4 calories per gram:

    European Journal of Clinical Nutrition 1994: Digestion and absorption of sorbitol, maltitol and isomalt from the small bowel: a study in ileostomy subjects [randomized controlled trial; moderate evidence]

    Gastroentérologie Clinique et Biologique 1991: Clinical tolerance, intestinal absorption, and energy value of four sugar alcohols taken on an empty stomach [randomized controlled trial; moderate evidence]

  22. European Journal of Clinical Nutrition 1996: Dose-related gastrointestinal response to the ingestion of either isomalt, lactitol or maltitol in milk chocolate. [non-controlled study; weak evidence]

    Journal of Nutritional Science and Vitaminology 2008: Suppressive effect of cellulose on osmotic diarrhea caused by maltitol in healthy female subjects [non-controlled study; weak evidence]

  23. In one study, overweight people assigned to drink only water for 12 weeks lost more weight and had less insulin resistance than people assigned to drink artificially-sweetened diet soda for 12 weeks – even though both groups followed the same weight-loss plan:

    The AmericanJournal of Clinical Nutrition 2015: Effects on weight loss in adults of replacing diet beverages with water during a hypoenergetic diet: a randomized, 24-wk clinical trial [randomized trial; moderate evidence]

  24. These are based on weak and inconsistent science but may still be a concern for many.