Navigating Artificial Sweeteners on a Ketogenic Diet

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Authors: Laura Dority, MS, RD, LD & Taylor Parrish, RDN, LD  

Editor: Amy Merwarth, RD, LD 

While a ketogenic diet can be a highly effective option for epilepsy, it also comes with challenges and nuances of adhering to this low-carbohydrate, high-fat dietary approach.  A common question that arises is the role of artificial and non-nutritive sweeteners which are often found in “keto-marketed” convenience foods.  Are sweeteners friends or foes in the realm of ketosis? 

Let's delve into the science and practical considerations.

First, what are artificial and non-nutritive sweeteners? Artificial and non-nutritive sweeteners are sugar substitutes that provide sweetness without the calories and carbohydrates of sugar. 

One advantage of artificial and non-nutritive sweeteners is their minimal impact on blood sugar and insulin levels. Since they are not metabolized in the same manner as sugar, they generally do not cause significant fluctuations in blood glucose, making them potentially suitable for those striving to maintain ketosis.

How do sweeteners work? Sweeteners bind to the receptors that register sucrose (sugar) molecules. This activates a signal to the brain that registers a sweet taste. Sweeteners are processed by the body differently than real sugar. Some are broken down into less desirable products while others aren’t broken down at all and may cause GI discomfort and impact gut health. 

It’s important to approach all sweeteners cautiously. Some individuals may experience cravings or increased appetite after consumption. Additionally, while these sweeteners are deemed safe for most people, some individuals may have sensitivities or adverse reactions to specific types.

Among the myriad of sweeteners available, some popular options include sucralose, aspartame, and saccharin. Non-nutritive sweeteners such as stevia, monk fruit extract, allulose, and erythritol are also favored choices among ketogenic enthusiasts. With any of these options, always be mindful of hidden sources of carbohydrates in products, such as fillers or bulking agents, which could potentially disrupt ketosis.

Let’s dig into each of these a little bit deeper. 

  • Sucralose (Brand name: Splenda) is an artificial sweetener that is 600 times sweeter than sugar. It is not absorbed or digested but instead is excreted in the stool. It has zero calories but is often combined with filler ingredients such as dextrose or maltodextrin that can add carbohydrates and calories. 

  • Aspartame is an artificial sweetener that is 200 times sweeter than sugar. You may see it used in conjunction with acesulfame potassium (Ace K). Many keto RDs advise patients to avoid aspartame. However, it can be difficult to meet hydration goals for some kids without the typical aspartame-sweetened beverages such as Crystal Light, Powerade Zero, or Propel Fitness Water. Your ketogenic team may suggest you double dilute these beverages to help cut back on intake while also achieving proper hydration. Aspartame is not heat stable so it should not be used in baking or any cooking method. 

  • Saccharin (Brand name: Sweet-N-Low) is an artificial sweetener that is 300 times sweeter than sugar but has a bitter or metallic aftertaste. You may see it used in conjunction with other sweeteners- such as aspartame. The body cannot metabolize saccharin, so it is excreted in the urine.

  • Stevia is a non-nutritive sweetener extracted from the leaf of the steviol glycoside plant. Depending on the form and brand, it is 150-300 times sweeter than sucrose. It generally has a slower onset of sweetness and a longer duration compared to sugar. Some forms have a bitter aftertaste so you may see stevia used in conjunction with other sweeteners- specifically erythritol. The least bitter-tasting form is stevia glycerite. 

  • Allulose & Tagatose are newer sweeteners in the keto world. They have a similar look, mouthfeel, and sweetness level to sugar. Allulose is naturally found in figs, raisins, and maple syrup while tagatose is found in milk and some fruits. Neither are fully metabolized and are excreted primarily in the urine. However, they do contain a small amount of carbohydrates and calories (0.4 calories per gram) so check with your keto team before using these products to determine if you should count any carbohydrates when consuming products with large amounts. 

  • Monk Fruit Sweetener (also known as Luo Han Guo) is a non-nutritive sweetener extracted from the fruit of a monk fruit tree native to Southern China. In its pure form, it is 300 times sweeter than sugar but has an unpleasant aftertaste. During processing the bad aftertaste is removed, and the final product is available in a liquid extract or powder. 

  • Sugar Alcohols are a broad category of sweeteners you may find in keto products. Sugar alcohols are made through a fermentation process and contain varying amounts of calories and carbohydrates. They are NOT all created equal. Xylitol, sorbitol, mannitol, and erythritol are the most common. Even moderate amounts of sugar alcohol can lead to GI upset, specifically loose stools. 

  • Erythritol is excreted in the urine, leads to less GI distress, and is considered the most keto-friendly. You will often find erythritol combined with other sweeteners such as stevia and/or monk fruit. Erythritol is not as sweet as these options, so it is added for its sugar-like crystalline appearance and texture while the stevia and monk fruit add the sweet taste. Some keto programs advise avoidance of all sugar alcohols (including erythritol) while other programs may allow a small amount of erythritol but advise you to count a small percentage in your carbohydrate limit. 

If you are looking for guidance on exact sweetener products that are keto-friendly check out this “Using Sweeteners on the Ketogenic Diet” guide from the Ketogenic Dietitians Research Network. 

How much do we absorb? Although most sweeteners are not absorbed and claim to be 0 calories, they can still cause GI side effects and harm the gut microbiome potentially triggering a glucose/insulin hormone response. This is different from the way sugar raises glucose but can still have an impact on ketosis. Your gut microbiome is as unique as your fingerprints so responses to sweeteners are individualized. 

Are sweeteners safe? There is limited long-term data (especially in children) about the use of sweeteners. Study results are inconclusive and often contradict each other. We know that excessive amounts of sugar are not good for overall health and certainly not epilepsy, but less is known about artificial and non-nutritive sweeteners. 

The U.S. Food & Drug Administration (FDA) has approved some sweeteners under the Generally Recognized as Safe (GRAS) category of food additives for use below what they call an acceptable daily intake (ADI). The FDA sets these levels based on amounts that have the potential to cause cancer or mutations.  A GRAS approval typically means that a product has not caused cancer in lab studies of animals.  Therefore, the amount needed to impact taste alterations or disrupt the gut microbiome is likely much less. 

Most of these ADIs are at a high level and likely will not be reached by children on a ketogenic diet. However, younger patients may be at risk for consuming amounts above the recommended guidelines if they rely heavily on keto-processed foods. If you want to learn more about the FDA’s stance on sweeteners, check out this resource.  

You can think of sweeteners as you would sugar, they are best consumed in moderation as excessive long-term ingestion may cause issues. Even plant-based or “natural sweeteners” which are often perceived as “healthier” may not be ideal. Many plant-based pharmaceuticals have side effects and the plants used can be toxic. 

The good news about most of these sweeteners is they are significantly sweeter than sugar so a small amount goes a long way in terms of flavor. 

How do I know how much sweetener is in a product? Unfortunately, unless it is a sugar alcohol, the manufacturer does not have to list the amount on the nutrition label. You will find the sweetener listed in the ingredient list, but the amount won’t necessarily be included.  

When should I introduce sweeteners to my ketogenic diet? When interviewing several ketogenic dietitians, it became clear that the utilization of sweeteners on a ketogenic diet is individualized. Some clinicians allow the use of sweeteners right away while others will wait a month to introduce them. Others will allow sweeteners once ketosis is achieved and then evaluate any change in ketosis with consumption. 

The consensus of the group was that it was up to families if they wanted to incorporate sweeteners into the plan. If having some sweeteners  make the ketogenic diet more feasible/attainable and seizure improvement was achieved, then the benefits likely outweigh the negatives. 

Here are some other take home tips we gleaned from our interviews with clinicians:   

  • Consume products with sweeteners in moderation (or not at all if you can),  try to limit to 1 serving or less/day.  

  • For beverages with sweeteners, dilute them. Beverages are the largest contributor of artificial sweeteners. 

  • Reserve consumption of sweeteners for special occasions (holidays, birthdays, parties). 

  • When in ketosis, the desire for sweets (aka cravings) tends to go away as glucose levels stabilize so don’t assume you will need sweet-tasting food on your keto journey. 

  • If you are craving something sweet, try cinnamon for a more subtle, natural sweetness. 

  • Keep in mind consuming sweeteners may lead to increased sweet cravings which could lead to non-compliance issues on the diet. 

In conclusion, sweeteners have a certain place and can be valuable tools for those following a ketogenic diet, offering a way to enjoy sweetness without compromising blood sugar control or ketosis. However, they are not all created equal and can impact each person differently because of the unique composition of our gut microbiome.  Sweeteners should be used mindfully and in conjunction with a balanced, whole-foods-based approach to nutrition. As always, consult with your ketogenic diet team to provide personalized guidance and support on navigating the intricacies of your ketogenic lifestyle.

References (or some light reading):