The Skinny on Sweeteners

By Dr. Adam Nally, D.O.

I am frequently asked which sweeteners can be used with a low carbohydrate ketogenic diet.  There are a number of sweeteners available that can be used with cooking; however, many of them are not appropriate for use with a low carbohydrate diet.

Because, weight gain and weight loss are controlled by 30 different known hormones, the master hormone being insulin, our overall goal is to lower the insulin levels in the blood stream.  Glucose (a carbohydrate in its most simple form) stimulates insulin to rise.   A Low carbohydrate diet works because insulin levels are significantly lowered throughout the day.  Elevation in cholesterol, elevation in triglycerides and production of uric acid occur because of insulin surges. The presence of glucose  (from carbohydrates or sugars) is the most common stimulus for insulin to rise.

First, and foremost, we must understand how these carbohydrates or sugars are labeled or named so that we can identify them in the food products we eat.  Most sugars are labeled with the ending “ose“. 

Sucrose, fructose, glucose, dextrose, lactose, and maltose are the common basic molecules that, when bound together, form the sugars you’ll see in the ingredient list of many products containing carbohydrates.  Sugars are the sweet tasting carbohydrates.  All of these types of sugars will stimulate a significant insulin rise and lead to weight gain, elevation in cholesterol and triglycerides. 

Other very commonly used names that you will find containing the sugars above are: white and brown sugar, fructose, succanat, corn syrup, high fructose corn syrup, honey, malt syrup, cane juice, cane syrup, rice syrup, barley syrup, maple syrup, molasses, turbinado, agave, monk fruit and fruit juice concentrate.  Beware of products that contain “no added sugar” because they will often contain sugar concentrates in the form of concentrated grape or apple juice.

Fructose is sometimes promoted as a suitable sweetener for patients with diabetes or people who are wanting to follow a low-carb diet; however even though it does not cause a significant insulin rise on its own, it is rapidly absorbed by the liver and converted into glycerol which leads to increased insulin level a few hours later, as well as raising triglyceride and cholesterol levels. 

Even though fructose occurs naturally in regular fruits and some vegetables, it is usually only present in small amounts. The fiber in these fruits or vegetables balances out the fructose content.  Today, fructose is added commercially to many foods in a highly refined purified form as high fructose corn syrup. Be careful because this form of fructose is found in soft drinks, ice teas, fruit drinks, jams, jellies, desserts, baked goods and even in many baby foods.  Fructose stimulates an extremely powerfu response in the liver to form triglycerides and leads to fatty liver disease, a form of non-alcoholic cirrhosis (J Am Diet Assoc, Lustig RH, 2010 Sep; 110 (9):1307-21).

Artificial Sweeteners

Most artificial sweeteners fall into a class that is referred to as “non-nutritive” meaning that they have no nutrient value to the human body. They provide a sweet taste to the senses without raising the blood sugar. These sweeteners can be useful in cooking and in maintaining blood sugars; however, it is essential to realize that many of them still stimulate an insulin response.


The most popular artificial sweetener in use today is aspartame (NutraSweet™, Equal™).  Aspartame is calorie and carbohydrate free.  It works great as a liquid sweetener; although, it is not the ideal sweetener for cooking. Because of its chemical instability, it breaks down under heat into its chemical constituents – namely phenylalanine and aspartic acid. This makes it notably unsuitable for cooking and for storage for more than a few days. 

Aspartame’s safety profile has been maintained by the manufacturer, and even though most people enjoy its use without any problems, there are a few people who may experience side effects including headache, stomach upset, migraine and exacerbation of depression (Neurology October 1, 1994, vol. 44: 1787).  Most diet sodas have stoped using this sweetener because of bad press about non-nutritive sweeteners in general, however, it still remains the only sweetener in diet soda that DOES NOT raise insulin levels in human studies. The following sodas still use aspartame and Dr. Nally is comfortable with patients using these products on a ketogenic diet: Diet Dr. Pepper™, Diet Cherry Dr. Pepper™, Diet Coke™ (if manufactured in the U.S.), Diet Mug Rootbeer™ and Diet A&W Cream Soda™.

Acesulfame Potassium

A second popular sweetener has been identified by the food and beverage companies called acesulfame potassium (Ace-K™, Sunette™). This sweetener is not fully absorbed by the gut, and yields no calories, nor does it raise blood sugar.  It also contains no carbohydrates.  To many palates, it has a slightly bitter savor, so it is often combined with aspartame to eliminate the bitter aftertaste.  The problem with acesulfame potassium is that there are a number of studies revealing it significantly increases insulin response without raising blood sugar.  This is exactly what one is trying to avoid to lose weight.  Studies show that the insulin response is as remarkable as if a person ingested an equivalent amount of glucose (Horm Metab Res. 1987 Jun; 19(6):233-8.).  It appears that acesulfame potassium works directly on the pancreas to stimulate insulin release (Horm Metab Res. 1987 Jul; 19(7):285-9).

This product is currently one of the most popular artificial sweeteners used in a number of low-carb/ketogenic products. It can be found in many of the protein bars and protein shakes on the market.   It is also found in Coke Zero™, Pepsi One™ and a number of other diet sodas.  I have found in my private medical practice that this sweetener significantly limits weight loss and raises both triglycerides and small dense LDL particles (the ones that cause atherosclerosis and vascular disease).


Sucralose is actually derived from regular sugar in such a way that the body doesn’t recognize it, and it is not absorbed.  It is found in a liquid form.  To crystallize sucralose, it must be bound to dextrose or maltodextrin forming the well known “yellow sweetener packet” named Splenda™. It contributes no calories or carbohydrates to the body in its pure form. Amazingly, it remains stable in heat and has become ideal for cooking and baking.  It is available as a bulk sweetener and actually measures equivalently to table sugar.  Be aware, however, Splenda™ is not carbohydrate free. Because of the maltodextrin used to make it bulk or crystalized for cooking, it contains about 0.5 g of carbohydrate per teaspoon, or about 1/8 of the carbohydrate of sugar. It does cause insulin release.  Research substantiates the effects that I often see clinically, frequently causing weight gain or difficulty with weight loss when used in excess (J Clin Oncol [Meeting Abstracts] June 2007 vol. 25(18) suppl 15127).  1 cup of Splenda™ is equivalent to 2 tablespoons of sugar, or 12-15 grams of carbohydrate in 1 cup of Splenda™.


Saccharine (Sweet’N Low™, SugarTwin™) is another unstable chemical when heated, however, it does not react chemically with other food ingredients and thereby stores well. It was used for quite some time as one of the original sweeteners.  It does not increase glucose or blood sugar, but it does stimulate an insulin response and can be problematic in weight loss (Am Jour Physiol – Endo April 1980 vol. 238 no. 4 E336-E340). It is often combined with other sweeteners to preserve their shelf life.


Cyclamate (SugarTwin™, Sucaryl™) is a sweetener available in Canada that is often combined with saccharine and is similar to sucralose. However, there is some controversy over this substance as it is known to cause bladder cancer in rats. There has been no human occurrence in its 30 years of study (Ann Oncol, October 2004, 15(10): 1460-1465.doi: 10.1093/annonc/mdh256). This product is currently banned in the US because of the notable potential for cancer. Cyclamate is stable in heat and therefore is an alternative for cooking and baking.


Stevia in the liquid form is a non-caloric natural sweetener which contains no carbohydrate. It is derived from a South American shrub and has been widely available for use in Asia for many years. The shrub is called Stevia rebaudiana that has very sweet tasting leaves. Stevia can be found in an extract or a white powder that is derived from these leaves.  Today it can be purchased commercially in extract, powder, or in a powdered green herbal leaf. It has an intense sweet taste which actually does have the potential to be slightly bitter. 

Stevia has two faults. First, it is so very sweet that it is hard to know just how much to use when cooking. Second, it often has a combined slightly bitter taste while at the same time a sweet taste to the palate. Therefore, stevia is often combined with fructooligosaccharide (FOS).  FOS is a sugar, but it is such a large molecule that the human gut cannot break it down and absorb it.   Because of this it does not raise blood sugar and it does not stimulate insulin release.  Stevia does not increase blood sugar and appears to improve insulin sensitivity in the pancreas (Metabolism, 2003 Mar;52(3):372-8.). FOS is only half as sweet in table sugar; therefore, it makes it a perfect partner for stevia.  

However, be aware that because of its popularity, a number of manufacturers have combined it with dextrose or maltodextrine to add bulk and use it in cooking.  Be cautious with these forms as the dextrose and maltodextrine will raise insulin and blood sugar levels. 

Oligofructans (Chicory Root)

Fructooligosaccharides (FOS) are often called oligofructans and they are actually short chain fibers derived from inulin. These oligofructans exhibit sweetness between 30-50% of sugar and have been used commercially since the 1980’s. They are commonly derived from chicory root, bananas, onions, garlic and the blue Agave. Because of their configuration, they resist breakdown by intestinal digestive enzymes, and instead, are broken down through fermentation in the colon by anaerobic bacteria. Therefore, eating larger amounts of FOS can lead to gastrointestinal “gymnastics.”  They do, however, combine well with other more intense sweeteners, and when combined, improve the overall sensation of sweetness and diminish any aftertaste that can occur with other sweeteners.  The fructooligosaccharides do not raise blood sugar and have not been shown to effect insulin. Therefore, they are a good sweetener to use with a low-carbohydrate or ketogenic diet. [Daubioul CA, et al., Effects of oligofructose on glucose and lipid metabolism in patients with nonalcoholic steatohepatitis: results of a pilot study. European Journal of Clinical Nutrition (2005) 59, 723–726. doi:10.1038/sj.ejcn.1602127 Published online 16 March 2005]. A great option that Dr. Nally recommends for use in cooking is a combination of FOS with erythritol called Swerve.  

Sugar Alcohols

Sugar alcohols are also called polyols.  These are a class of long-chain carbohydrates that are neither sugar nor actual alcohol. Included in this group are maltitol, sorbitol, mannitol, xylitol, erythritol, lactitol, and hydrolyzed starch hydrolysates (HSH).  These long-chain carbohydrates give the texture and sweetness of sugar to corn syrup and can be used to make crunchy toffee, chewy jelly beans, and slick hard candies, moist brownies and creamy chocolate. However, they are partially, but incompletely, absorbed by the human intestine.  This causes side-effects include gas, bloating and diarrhea for a significant portion of people.

The other challenge is that there seems to be notable variability in people’s ability to absorb these long-chain carbohydrates. In other words, these sweeteners affect people differently and actually increase the blood sugar and insulin release in varying degrees among individuals. 

Maltitol, sorbitol and xylitol seemed to be worse offending culprits in this class of artificial sweeteners. They cause an insulin response of about half that of normal sugar (American Journal of Clinical Nutrition, April 1997, Vol 65, 947-950).  Maltitol and sorbitol have also been shown to increase cholesterol (International Journal for Vitamin and Nutrition Research, 1990 Vol. 60 No. 3 pp. 296-297). Erythritol is absorbed and excreted unchanged and appears to have no insulin response (Food and Chemical Toxicology, Dec 1998, Volume 36, Issue 12,  Pages 1139-1174). Erythritol also seems to have an inhibiting effect on fructose absorption (  Dr. Nally has found that a great combination sweetener using Stevia and erythritol is called Truvia.  In the clinical use of Truvia, insulin and blood sugar appear to remain stable, however, the erythritol can cause additional “gastrointestinal gymnastics” when used in excess! 

So, in summary, which sweeteners will not cause weight gain or cholesterol changes?  From the research that is presently available, aspartame, Stevia, Chicory Root/fructooligosaccharides (FOS) and erythritol have no weight gain, insulin stimulus or cholesterol changes associated with them.

Splenda is a great sweetener, but even moderate quantities will limit your ability to lose weight. All of the other sweeteners listed above have significant insulin response when ingested and will make it more difficult to lose weight and even maintain weight. 

I’ve been using ketogenic diets since 2005.  In that time, I have found personally, and clinically with the patients in my practice, that combinations of Stevia, chicory root and erythritol, when used in baking, seem to provide adequate texture and remove any aftertaste that may be found when using them individually.  These combinations also have no effect on weight loss, weight regain or adverse metabolic changes when used with a ketogenic lifestyle.

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