There are a number of sweeteners you can use on a keto or fasting diet without interfering with your goals. These can be considered keto and fasting safe.
However, there are many sweeteners to avoid, and a couple of traps. I've reviewed all sweeteners for you below and given you some actionable takeaways so you can navigate this issue easily.
What Types of Sweeteners Can I Use?
Here is a full list of sweeteners classified by whether they are keto/ fasting safe or not, and whether they are natural or artificial.
| Natural | Artificial |
Keto/ Fasting Safe (Don't Increase Glucose Significantly) | Erythritol, Xylitol, Stevia, Monk Fruit (Luo Han Guo), Allulose, Sorbitol, Mannitol | Aspartame, Sucralose, Lactitol, Saccharin, Acesulfame K, Neotame |
NOT Keto/ Fasting Safe | Sugar, Honey, Maple Syrup, Dextrose, Glucose, Agave Syrup, Coconut Sugar, Brown Rice Syrup, Molasses, Date Sugar, Yacon Syrup | High Fructose Corn Syrup (HFCS), Polydextrose, Glucose Syrup, Maltitol, Hydrogenated Starch Hydrolysates (HSH), Glycerol (Glycerin or Glycerine), Trehalose, Polyglycitol |
To keep it simple we've classified the sweeteners in green, yellow and red zones for you in a traffic light system:
Green Zone: Everyone can use these sweeteners. They are keto/ fasting safe, and natural.
Yellow Zone: While these are keto/ fasting safe, some people prefer not to use artificial ingredients. Use these based on your personal view on whether you want to accept artificial sweeteners or not.
Red Zone: Everyone should avoid these because they are not keto/ fasting safe. They will increase your blood sugar, and decrease your ketones.
Important Specifics to Be Aware Of
Polyols or Sugar Alcohols?
Sugar alcohols and polyols are the same category of sweeteners. These terms are used interchangeably.
The sweeteners fitting under this category include:
Maltitol
Sorbitol
Mannitol
Lactitol
Neotame
Isomalt
Hydrolysates (HSH)
Glycerol (Glycerin or Glycerine)
Trehalose
Polyglycitol
You will find the gram amounts of these listed in nutrition tables. They are a sub-category of carbs that doesn't impact blood sugar significantly, so can be subtracted from the total carb amount to get net carbs.
Maltitol - The Polyol that is a Hidden Net Carb
There is one specific sweetener (polyol) that you should be extra wary of when checking your food labels.
Maltitol is what we call a hidden net carb. This is because the nutritional information panel does not classify it as a net carb. It will state it as a "polyol", which is subtracted from Carbs.
However, this isn't accurate. Maltitol increases blood sugar significantly and is not keto/ fasting safe. It can lower your circulating blood ketone levels and take you out of ketosis.
Maltitol is what we call a "hidden net carb". So you should not count it as a polyol. Always count it directly as a Carb.
Actionable Takeaways
As a general rule, stick to the keto/ fasting safe sweeteners in the green zone: Erythritol, Xylitol, Stevia, Monk Fruit, Allulose.
If you don't mind artificial sweeteners, then you can also use the sweeteners in the yellow zone: Aspartame, Sucralose, Sorbitol, Mannitol, Lactitol, Saccharin, Acesulfame K, Neotame
Avoid all sweeteners in the red zone.
Always check the ingredients labels for "Maltitol" because it's a hidden net carb that won't show up in the Carb grams on the label.
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