Sugar Substitutes: Keto-Friendly Or Not?

Sugar substitutes are a great way to satisfy your sweet tooth while on a keto diet. However, not all sugar substitutes are created equal. Some may even kick you out of ketosis and induce a rollercoaster of sugar cravings.

So, what makes a good keto sweetener? Well, the best options will have little to no calories and net carbs and will have no effect on insulin levels. They will also be safe to consume and will not turn bitter or toxic when exposed to high temperatures.

- Stevia

- Monk fruit

- Erythritol

- Allulose

- Xylitol

- Tagatose

- Sucralose

Natural Sweeteners: e.g. Stevia, Monk Fruit

Natural sweeteners such as stevia and monk fruit are excellent alternatives to sugar for those on a keto diet. They are derived from plants and are significantly sweeter than sugar, with stevia being 200 to 300 times sweeter, and monk fruit 150 to 200 times sweeter. This means that only a tiny amount is needed to achieve the same level of sweetness as sugar.

Stevia is a natural sweetener derived from the Stevia rebaudiana plant, which is native to South America. It has been linked to lower blood sugar levels and reduced inflammation, diarrhea, and tumors. It may also help improve immune system regulation and lower blood pressure. However, some people find that stevia has an aftertaste, and it is not recommended for use in chocolate recipes as it can cause a severe delayed flavor impression when heated.

Monk fruit, also known as luo han guo, is native to Southeast Asia and is said to resemble a cross between a lime and a melon. The fruit itself contains fructose and sucrose, but its intense sweetness comes from non-caloric compounds called mogrosides. Monk fruit is generally recognised as safe by the FDA and does not raise blood sugar or insulin levels. It is often mixed with stevia to blunt stevia's aftertaste, and with erythritol to improve its performance in cooking. However, it is more expensive than stevia and erythritol, and may be harder to find.

Both stevia and monk fruit have a glycemic index of 0, meaning they should not affect blood sugar or insulin levels. However, some cheaper forms of stevia are mixed with other sweeteners or bulking agents, such as maltodextrin, dextrose, and polydextrose, which could impact blood sugar.

Sugar Alcohol Sweeteners: e.g. Erythritol, Xylitol, Allulose

Sugar alcohol sweeteners are a type of natural sweetener that is a hybrid of sugar molecules and alcohol molecules. They are called sugar alcohols because of their similar chemical structure to sugar, which allows them to activate the sweet taste receptors on your tongue. However, unlike sugar, sugar alcohols contain far fewer calories and net carbs.

Erythritol

Erythritol is a sugar alcohol found naturally in small quantities in some fruits and vegetables, but it is commonly extracted from corn. It is only partially absorbed and digested by the intestinal tract and contributes a negligible amount of calories and net carbs to the diet. Erythritol does not change blood sugar or insulin levels, making it a popular choice for those on a keto diet. It has also been found to act as an antioxidant and may improve blood vessel function in people with type 2 diabetes, although more studies are needed to confirm this. Erythritol is generally recognised as safe by the FDA, but a 2023 study showed a link between high blood levels of erythritol and an increased risk of heart attacks and strokes. However, this association was based on very weak data, and other studies suggest erythritol may be beneficial to health. Erythritol is 70% as sweet as table sugar and is known for leaving a cooling taste in people's mouths. It can cause bloating, gas and diarrhoea in some people, although this is less likely than with other sugar alcohols. Erythritol is often used in baking and cooking and can be substituted for sugar in a wide variety of recipes.

Xylitol

Xylitol is another sugar alcohol commonly found in products like sugar-free gum, candies and mints. It is as sweet as sugar but contains just 3 calories per gram and 4 grams of carbs per teaspoon. Like other sugar alcohols, the carbs in xylitol do not count as net carbs as they do not raise blood sugar or insulin levels to the same extent as sugar. Xylitol can be easily added to tea, coffee, shakes or smoothies, and it also works well in baked goods, although it may require a bit of extra liquid in the recipe as it tends to absorb moisture and increase dryness. Xylitol is known to be highly toxic to dogs and other pets.

Allulose

Allulose is a "rare sugar" that occurs naturally in a few different foods, including figs, raisins and wheat. It has a molecular structure almost identical to fructose, but the body cannot metabolise it, so it passes into the urine without being absorbed or used for energy. As a result, allulose has almost no calories and doesn't impact blood glucose levels. It also resists fermentation by gut bacteria, making it unlikely to cause gas or bloating. Allulose is still fairly new, so there isn't as much research on its health benefits, although it is generally recognised as safe by the FDA. Early research suggests it may decrease inflammation and help with weight loss in people with obesity or type 2 diabetes. Allulose is about 70% as sweet as table sugar and is an excellent substitute for sugar in baked goods.

Synthetic Sweeteners: e.g. Sucralose, Aspartame, Saccharin

Synthetic sweeteners, also known as artificial sweeteners, are created in laboratories from chemicals and other substances (such as sugar, in the case of sucralose). These include:

• Acesulfame potassium (Ace-K)
• Aspartame
• Saccharin
• Sucralose

These synthetic sweeteners have been approved for public consumption by the US FDA, which sets an acceptable daily intake limit for each type. However, some of them have been the subject of health concerns and controversies.

Acesulfame Potassium (Ace-K)

Ace-K is one of the most common sweetening agents in flavoured water enhancers and sugar-free drinks. It is sold under brand names such as Sunett and Sweet One. While it contains no calories or carbs, one trial suggested it might raise blood sugar in some people. Additional research on its safety has been advised, based on rodent studies. Ace-K is about 200 times sweeter than table sugar and is often combined with other sweeteners.

Aspartame

Aspartame is the most widely used sugar substitute in the US. It is sold under brand names such as Equal and NutraSweet. Aspartame contains no calories or carbs and hasn't been shown to raise blood sugar or insulin levels in most studies. However, sweetener packets of aspartame contain nearly 1 gram of carb each from dextrose. The FDA considers aspartame safe when used in moderation, but some researchers believe its safety requires further study. People have reported side effects such as headaches and dizziness. Aspartame is about 200 times sweeter than table sugar.

Saccharin

Saccharin is the oldest synthetic sweetener, marketed under brand names such as Sweet'n Low and Sugar Twin. While pure saccharin contains no calories or carbs, sweetener packets contain dextrose. It is well-known for its bitter aftertaste. The FDA attempted to ban saccharin in the 1970s due to studies showing a link to bladder cancer in rodents. However, this association was never found in humans. Overall, research on saccharin's health effects is mixed, with some studies suggesting negative effects on gut and metabolic health. Saccharin is 200 to 700 times sweeter than table sugar.

Sucralose

Sucralose is the sweetener found in Splenda, marketed as a sugar substitute that "tastes like sugar because it's made from sugar". While sucralose itself has no calories or carbs, Splenda packets contain dextrose, which does contribute calories and carbs. Research on sucralose is mixed, with some studies finding no impact on blood sugar or insulin, while others suggest it may increase blood sugar and insulin when consumed with carbs. Sucralose is about 600 times sweeter than table sugar.

Sweeteners to Avoid: e.g. Maltodextrin, Sorbitol, Agave Nectar

Sweeteners to Avoid on a Keto Diet

While there are plenty of keto-friendly sweeteners, there are also many that are not ideal for a keto diet. Here are some sweeteners that are high in carbs and can increase your blood sugar levels, interrupting ketosis:

Maltodextrin

Maltodextrin is a highly processed sweetener derived from starchy plants like rice, corn, or wheat. It contains the same amount of calories and carbs as regular sugar. It is often used as a filler in other sugar alternatives, so be sure to check the ingredients label.

Sorbitol

Sorbitol is a sugar alcohol that ends with "-ol", like other sugar alcohols (e.g., erythritol and xylitol). It has fewer calories and net carbs than regular sugar, but it may raise blood sugar levels for many people and should be avoided on a keto diet.

Agave Nectar

Agave nectar is about 80% fructose, which can decrease your body's sensitivity to insulin and contribute to metabolic syndrome. This makes it difficult for your body to regulate blood sugar levels. Agave syrup has the highest fructose content at more than 60%, making it potentially worse than sugar.

Other sweeteners to avoid on a keto diet include honey, coconut sugar, maple syrup, and dates. These sweeteners are naturally based but will increase your blood sugar levels and should be avoided.

Sweeteners for Baking: e.g. Stevia, Monk Fruit, Erythritol

Stevia

Stevia is a natural sweetener derived from the Stevia rebaudiana plant. It is 200 to 300 times sweeter than sugar and has been linked to lower blood sugar levels. It is safe for people with diabetes as it generally does not raise blood sugar levels. It is available in liquid and powdered form and can be used to sweeten everything from drinks to desserts. However, it has a bitter aftertaste and is not suitable for baking, especially chocolate recipes, as many people experience a delayed and unpleasant flavour. It is also more expensive than sugar and most other artificial sweeteners.

Monk Fruit

Monk fruit is a small, green gourd grown in Southeast Asia. It is 150 to 200 times sweeter than sugar and contains no calories, carbohydrates, sodium, or fat. It is generally recognised as safe by the FDA and does not impact blood sugar levels. It is available in liquid, granule, and powder forms and is safe for children, pregnant women, and breastfeeding women. However, it is difficult to grow and expensive to import, and not everyone likes its fruity taste. It also needs to be mixed with other sweeteners for baking.

Erythritol

Erythritol is a sugar alcohol found naturally in some fruits and vegetables and is commonly extracted from corn. It contributes the least calories and net carbs of all sugar alcohols and does not change blood sugar or insulin levels, making it very popular. It has also been found to act as an antioxidant and may improve blood vessel function in people with type 2 diabetes. It is available in granulated or powdered form and is easy to use to replace sugar in recipes. However, it tends to leave a cooling taste in people's mouths and can cause bloating, gas, and diarrhoea in some people.

Frequently asked questions