What makes a sweetener "keto"
A sweetener earns the keto-friendly label when it does two things: it adds little or no digestible carbohydrate, and it barely moves blood glucose or insulin. Table sugar fails both, with roughly 4g of carbs per teaspoon and a glycemic index of 65. The guide below ranks the common options by those two criteria, plus a practical third one: how they actually taste and bake.
The metric to watch is the glycemic index (GI), a 0 to 100 scale of how fast and how high a food pushes blood sugar. Pure glucose is 100, table sugar is 65, and a genuine keto sweetener sits at or very near 0.
The best keto sweeteners
Erythritol (GI 0)
A sugar alcohol the body absorbs but cannot metabolize, so it leaves the body almost unchanged with near-zero calories and net carbs. About 70% as sweet as sugar. Downsides: a slight cooling aftertaste and a tendency to recrystallize in cold or wet recipes. It is the most widely sold granulated option and the workhorse of keto baking.
Allulose (GI 0)
A rare sugar found naturally in figs and raisins. It tastes and behaves remarkably like real sugar: it dissolves cleanly, browns and caramelizes, and keeps baked goods soft. No cooling aftertaste. It is about 70% as sweet as sugar and the best choice for sauces, caramel and ice cream. The only catch is price and slightly lower availability.
Monk fruit (GI 0)
Extracted from a small Asian melon, monk fruit is 150 to 200 times sweeter than sugar, so pure extract is used in tiny amounts. Most products sold as monk fruit sweetener are actually monk fruit blended with erythritol to make a 1:1 sugar replacement. No measurable effect on blood sugar and a clean taste.
Stevia (GI 0)
A plant-derived sweetener 200 to 300 times sweeter than sugar, with zero glycemic impact. Its weakness is a licorice-like bitterness that some people detect strongly, especially at higher doses. It works best in drinks and blended with erythritol to round out the flavor.
The use-with-caution group
Xylitol (GI 7 to 13)
Another sugar alcohol. It bakes well and has real dental benefits, but unlike erythritol it carries about 2.4 calories per gram and a small but real glycemic impact, so count roughly half its carbs as net. Two warnings: it commonly causes bloating and digestive upset in larger amounts, and it is highly toxic to dogs even in tiny quantities. Keep it off the counter if you have a pet.
The sweeteners to avoid on keto
- Maltitol (GI 35 to 52). The most deceptive of all. It is marketed as a sugar alcohol and often hidden in sugar-free and keto candy, but it raises blood sugar almost as much as table sugar. Do not subtract it from net carbs.
- Agave nectar. A low GI is misleading here. Agave is around 85% fructose and packed with carbs. It is sugar with better marketing.
- Honey, maple syrup, coconut sugar. All natural, all still sugar. Coconut sugar has a GI around 54 and the same carb load as cane sugar.
- Dextrose, glucose, maltodextrin. These are pure fast carbs. Maltodextrin has a GI as high as 110, higher than sugar itself, and hides in countless processed products.
How to read sugar alcohols on a label
In the United States, the net-carb shortcut is total carbs minus fiber minus sugar alcohols. That math only works cleanly when the sugar alcohol is erythritol, which truly has no glycemic impact. For xylitol, subtract only half. For maltitol, subtract nothing. If a keto bar lists maltitol, treat its carbs as real carbs. For the full method, see our guide to net carbs vs total carbs.
Baking conversions
- Erythritol and allulose: about 70% as sweet as sugar, so use roughly 1 and 1/3 cups per cup of sugar called for.
- Monk fruit and erythritol blends: formulated to replace sugar 1:1. Check the bag.
- Pure stevia or pure monk fruit extract: 1 teaspoon can replace a full cup of sugar. Measure with a tiny spoon and taste as you go.
- For caramel, browning or chewy texture: allulose wins. Erythritol stays granular and can recrystallize.
Digestive tolerance
Sugar alcohols ferment in the gut, and too much at once causes bloating, gas or a laxative effect. Tolerance ranks roughly like this: allulose and erythritol are best tolerated, xylitol and maltitol the worst. If you are new to keto baking, start with small portions and see how you feel before serving a whole tray.
The bottom line
For everyday use, a monk fruit or stevia blend with erythritol covers drinks and most baking. Keep a bag of allulose for anything that needs to brown, caramelize or stay soft. Avoid maltitol entirely, and treat agave, honey and coconut sugar as the sugars they are.
For the bigger picture on which foods quietly hold carbs, read our complete list of foods to avoid on keto, and put your new sweeteners to work with these easy keto desserts under 5g carbs.
For the full picture on this topic, check our complete keto diet guide: the science, macros, food list, 7-day plan and FAQ in one place.
Cetona builds your personalized keto meal plan with the macros already calculated, so every recipe and dessert stays inside your daily carb limit, with no label math required.