Over the past several years, the ketogenic diet has increased in popularity among many people looking to lose weight quickly. Originally developed in the 1920s to help children with intractable epilepsy, the diet eliminates nearly all carbohydrates.
The classic keto diet “is a high fat, adequate protein, low carbohydrate diet designed to produce ketosis through mimicking the metabolic changes of starvation, forcing the body to use fat as its primary source of energy,” says Cathy Leman, a registered dietitian nutritionist and founder of Dam. Mad. About Breast Cancer, a nutritional consulting firm based in greater Chicago that’s aimed at helping breast cancer patients and survivors.
“This original keto diet is 90% fat, 6% protein and 4% carbohydrate,” Leman says. Other variations have also cropped up with slightly different ratios of fat, carbs and protein, but the hallmark of the keto diet is that the vast majority of calories are derived from fat, which forces the body into this state of ketosis, which occurs when fat becomes the primary fuel for the body.
No matter whether you’re following a classic keto diet or a modified version, the key is to remove nearly all carbohydrates from the diet. However, doing so takes virtually everything sweet with it, and sometimes you might be craving a sweet treat. In these cases, you’ll need to rely on a keto-friendly sweetener, and there are currently several options available to you.
For a sweetener to be considered keto-friendly, it has to contain “virtually zero calories and have a glycemic index of zero,” meaning that it doesn’t elevate your blood sugar level when you ingest it, says Rami Abrams, president of So Nourished, a low-carb company that provides a range of keto-friendly products.
He lists the following four sweeteners as being good options for keto dieters because “none of these four sweeteners have any impact on blood glucose, which is critical for anyone on a keto diet and for people with diabetes. These sweeteners can be used for baking, cooking and sweetening drinks like tea and coffee.”
Of course, there are other reasons someone might follow a sugar-free diet, and these sweeteners could work for those goals as well.
This extract from the leaves of a South American shrub called Stevia rebaudiana, is “far sweeter than sugar and should be used in tiny quantities, such as 1/32 of a teaspoon or 1/64 of a teaspoon, aka a drop,” Abrams says.
Using too much stevia extract, which usually comes in liquid form but is also available in powder or granular forms, can create “a strong bitter aftertaste,” so go easy. Just a couple of drops of stevia can sweeten a cup of tea or coffee.
People who have an allergy to any plant from the Asteraceae family (including ragweed, daisies, chrysanthemums and sunflowers) should avoid stevia, as it’s related to these plants and could trigger an allergic reaction.
Monk fruit extract
Indigenous to Southeast Asia, monk fruit is small and green and looks like a melon. Fresh monk fruit has few uses, so it’s usually dried and made into medicinal teas.
Monk fruit sweetener is made from the fruit’s extract and is typically available as a liquid, a powder or granules. Sometimes this extract is blended with dextrose or other ingredients to produce a smoother, more balanced sweetness. Dextrose is a type of sugar, so if the sweetener is blended with it, it may not be keto-friendly.
Monk fruit extract is about 200 times sweeter than sugar and contains no sugar and no carbohydrates. As with stevia, not everyone loves the taste of monk fruit extract, and some users report a strange aftertaste.
Erythritol is a sugar alcohol, along with xylitol (often found in chewing gum and toothpaste), sorbitol and maltitol. These sugar alcohols are derived from sugar molecules by fermenting glucose from corn or wheat starch, but they’re sugar-free.
Sugar alcohols have been found to be safe alternatives to sugar, but they can sometimes trigger digestive issues in some users because the body can’t digest them. They sometimes are fermented in the colon, producing gas and bloating. Erythritol has a much lower propensity for causing gastric upset compared to other sugar alcohols because most of it is absorbed by the bloodstream before it reaches the colon.
Erythritol contains just 0.24 calories per gram, much lower than table sugar’s 4 calories per gram and it does not elevate blood sugar levels. It has about 70% of the sweetness of regular table sugar.
Abrams notes that “the first generation of keto sweeteners were primarily maltitol and xylitol. Both are sugar alcohols like erythritol, however, they are considerably higher on the GI scale (35 and 7, respectively), cause bloating and gas after a much lower quantity is consumed than erythritol and contain some calories per serving.”
“Some of these sugar alcohols probably have a safer track record than some of the artificial sweeteners” such as saccharine, says Liz Weinandy, a registered dietitian with the Ohio State University Wexner Medical Center. “Sugar alcohols provide a negligible amount of carbs,” she says, and “erythritol and xylitol are two that we’re seeing more in foods.”
Also known as D-psicose, allulose is found in a few foods, such as wheat, raisins and figs, but it can also be converted from corn and other high-sugar plants with enzymes. It’s a monosaccharide, or single sugar, similar in molecular structure to glucose and fructose. It slips through the digestive system without triggering the body’s typical response to sugar and is absorbed into the bloodstream and eliminated via urine excretion without ever being used as fuel, making it a non-nutritive and zero glycemic sweetener.
Allulose tastes a lot like sugar and is about 70% as sweet as regular table sugar, “so it would take about 1 and 1/3rd cup of either erythritol or allulose to match the sweetness of 1 cup of sugar in a recipe,” Abrams says, adding that “erythritol and allulose are much closer to sugar in appearance and serving size” than monk fruit extract or stevia.
Other Sugar-Free Sweeteners
The following common sugar substitutes rely on chemical engineering to get their calorie-free sweet status. You’ve likely encountered these sweeteners at various times throughout your life, as they are found in a wide range of processed and commercially available food items.
— Aspartame. This king of so-called non-nutritive sweeteners is marketed under the brand name NutraSweet and Equal and is a calorie- and carb-free sugar substitute. It’s found in a wide range of diet sodas and other sugar-free items and is about 200 times sweeter than sugar. Extensive research has been conducted into the safety of aspartame, and it has been deemed safe for use by the U.S. Food and Drug Administration, but research continues into the long-term effects of this food additive. People who have the rare metabolic condition phenylketonuria and those with advanced liver disease are warned not to use aspartame, as they typically can’t metabolize an amino acid contained in aspartame. Over time, this can lead to brain damage.
— Sucralose. Sucralose starts out life as sugar, but by substituting chlorine atoms for other atoms in the sugar molecule, it becomes sucralose, a calorie-free, intensely sweet substance. It’s commercially marketed as Splenda and is about 600 times sweeter than sugar. It’s often used in baking as it’s more stable at high temperatures than other sugar substitutes. It was approved by the FDA for human consumption in 1998 and is generally considered one of the safer artificial sugar substitutes on the market.
— Saccharin. Saccharin is about 300 times sweeter than sugar, but is calorie-free. Originally developed in the 1870s, it’s the oldest sugar alternative, but it also has a checkered history, having been linked to bladder cancer in rats in the 1970s. Since then, additional studies have been conducted, and it’s been deemed safe for humans to consume. Long-range studies are still ongoing.
Selecting the Right Sweetener
Weinandy recommends considering what your goals are for following a ketogenic diet before selecting a keto-friendly sweetener. “If you’re doing it for seizure control, you probably need to pay a little more attention than if you’re doing following it to lose weight or lower blood sugar,” she says.
If you’re being very strict about staying keto, opt for whichever of the zero glycemic index sweeteners you prefer the taste of, and skip any added table sugar. If you’re a little less restrictive, you can occasionally add a bit of regular sugar, but you should limit these dalliances as much as possible as they’re counterproductive to getting into and staying in ketosis.
In all cases, Weinandy encourages people to aim for “moderation, because there can definitely be some rebound effects,” meaning that your blood sugar level might rise after consuming these sugar substitutes. “Some studies have shown that sugar substitutes can actually raise blood sugar in some people. It doesn’t look like it does that for the majority of people, but some small studies are showing that rebound,” she says, which could be counterproductive for your goals.
Because these sugar alternatives are sweet — often hundreds of time sweeter than table sugar — they can also boost your cravings for sweet things, “which would be really detrimental,” she says, as this can lead some dieters to wander off the prescribed plan and into the candy aisle.
Weinandy notes that science still doesn’t understand exactly why some people see a blood sugar rebound or increased sugar cravings from using non-nutritive sweeteners, but “what’s been hypothesized is that the body expects something sweet after tasting it on the tongue, and then the pancreas puts out insulin thinking that a high-sugar treat is enroute. The insulin levels go up and then the liver excretes sugar to bring it down,” a complex process that’s still being researched.
Lastly, Weinandy adds that as food scientists continue to work on finding no-calorie sugar alternatives to slake our national sweet tooth, you may hear of new sugar substitutes emerging.
For example, an emerging low-sugar sweetener called yacón syrup, is derived from the root of the South American yacón plant, also called Smallanthus sonchifolius . Using a process similar to how maple syrup is made, a sweet, dark syrup that looks and behaves like molasses is extracted and has been used as a diabetes medicine for centuries in South America. The syrup contains about a third of the calories of sugar, roughly 20 calories per tablespoon, and is gaining popularity as a low-calorie sugar alternative. It’s just another option you may be able to incorporate depending on your needs and goals.
With all these options, Weinandy stresses moderation and looking at “the full scope of the diet. We can get ultra-focused on the sugars piece, but forget to ask what the diet is providing and whether you’re getting the necessary nutrients that you need.” Instead of thinking strictly about staying low carb or high fat, she encourages those on the ketogenic diet to look at the whole scope of what they’re eating and how it affects their body.
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