Low-carb sweeteners, the best and the worst
The numbers above are based on the effect the sweetener has on blood sugar and insulin resistance, for an equal amount of sweetness compared to white sugar (100 percent pure sugar).1
Negative effects of all sweeteners
Note that while the sweeteners to the left above have small or non-existent direct effects on blood sugar levels (and weight), they still have other potential negative effects.
All sweeteners maintain cravings for sweet foods. Also, when added to caloric foods – e.g. a muffin – they result in a significantly increased feeling of reward when eating it. So by adding sweeteners to your foods you’re significantly increasing the risk that you’ll end up eating more than you need. This can slow down weight loss, or cause weight gain.
There are scientific studies showing that even adding non-caloric sweeteners to diet beverages may make it harder to lose weight.2
This means that all sweeteners, including the non-caloric ones above, have potentially negative effects. If you’re able to, you may be better off just avoiding all of them. Note that on a low-carb diet cravings for sugary foods tend to decrease over time, making it easier and easier to avoid them.
However, most people enjoy something sweet once in a while. If so, we suggest trying to do it only occasionally. Keep reading to learn more, and to be able to make better-informed choices.
Using sugar as a sweetener
Note that many sweeteners – white or brown sugar, maple syrup, coconut sugar and dates – have a number of exactly 100. This is because these sweeteners are made up of sugar. To get the same amount of sweetness as white sugar, you’ll get about the pretty much an identical effect of these sweeteners, on blood sugar, weight and insulin resistance.
Sugar is bad, no surprise, so these are bad options, especially if you’re on a low-carb diet. Avoid.
Even worse than sugar: fructose
Amazingly, there are sweeteners that are even worse than sugar. Regular sugar contains 50% glucose and 50% fructose. These sweeteners contain more fructose than glucose. While these sweeteners are slower to raise blood glucose – resulting in a deceptively low GI3 – they have even more harmful effects. Fructose in excess can result in fatty liver and insulin resistance, which increases the long-term negative effects of carbohydrates you eat later.
These sweeteners with excess fructose – high fructose corn syrup (soda), fruit juice concentrate, honey and agave syrup – can likely have a slightly worse long-term effect than pure sugar. Thus we give them a number of 100+. Worst of all, with the highest fructose content of all? Agave syrup.
This is not to say that sugar is good. Clearly sugar is potentially very bad. But these sugars are super sugars. They are not good options on a low-carb diet.
As stated above, we see potential negative effects of all sweeteners. However, if you’re going to use one there are worse and less bad choices. Here are our top 3 suggestions:
Not-too-bad option #1: Stevia
Stevia comes from the plant Stevia rebaudiana Bertoni, which is native to South America, where it has been used for several hundred years. Steviol glycosides extracted from the plant are responsible for its sweet taste.
- Stevia doesn’t contain carbs or calories and does not raise blood sugar.
- Stevia appears to be safe and nontoxic.
- Stevia doesn’t really taste like sugar. It has a licorice-like flavor and an undeniable aftertaste when used in moderate to large mounts. Therefore, using it sparingly is recommended.
- At least one study has indicated that large amounts of stevia might increase insulin secretion, possibly increasing fat storage and reducing stevia’s advantage over sugar.4
Sweetness: 200-350 times sweeter than table sugar.
Best choices: Liquid stevia or 100% pure powdered or granulated stevia. Note that packets of granulated stevia such as Stevia in the Raw contain the sugar dextrose. The brand Truvia instead contains added erythritol (see below).
Not-too-bad option #2: Erythritol
Erythritol is a sugar alcohol, a compound that resembles sugar but is only partially digested and absorbed by the body. Erythritol occurs naturally in plants like grapes, melons, and mushrooms in small amounts. However, as a commercial sweetener, it is usually made from fermented corn or cornstarch.
- Erythritol provides almost zero calories and is virtually carb free. After being absorbed, it passes into the urine without being used by the body.
- Erythritol might be helpful in preventing dental plaque and cavities, compared to other sweeteners.5
- Erythritol has a noticeable cooling sensation on the tongue, particularly when used in large amounts.
- Although it causes fewer digestive issues than most sugar alcohols, some people have reported bloating, gas and loose stools after consuming erythritol.
- While absorbing erythritol into our blood and excreting it into the urine appears to be safe, there is likely some potential for unknown health risks.
Sweetness: 70% as sweet as table sugar.
Not-too-bad option #3: Xylitol
Like erythritol, xylitol is a sugar alcohol found in fruits and vegetables in small amounts. It is produced commercially from corn cobs or birch trees. Xylitol is one of the most frequently used sweeteners in sugar-free chewing gum and mouthwash.
Note however, that xylitol is only low carb, not zero carb. So it’s not a perfect choice on a keto low-carb diet (below 20 grams per day). The carbs quickly start to add up.
- Xylitol has a low glycemic index of 13, and only 50% is absorbed in your small intestine. When used in small amounts, this results in a very minor impact on blood sugar and insulin levels.
- Although its level of sweetness is identical to table sugar, xylitol contains 2.5 calories per gram, whereas sugar provides 4 calories per gram.
- Like erythritol, it’s been shown to help prevent cavities, compared to other sweeteners.
- Because 50% of xylitol is not absorbed but instead fermented by bacteria in your colon, it may cause digestive issues (gas, bloating etc.) when consumed in moderate to large amounts.
- Although xylitol is safe for humans, it is toxic and potentially lethal for pets, like cats and dogs. If you use xylitol, make sure to keep it away from your animals.
Sweetness: Equivalent in sweetness to table sugar.
Best choices: Organic granulated xylitol made from birch.
The “zero-calorie” sweeteners that are almost 100% carbs
Packets of Stevia in the Raw, Equal, Sweet’n Low and Splenda are labeled “zero calories”, but this is just a trick. FDA rules allow servings under 1 gram of carbs and under 4 calories per serving to be labeled “zero calories”. So these manufacturers cleverly package about 0.9 grams of pure carbs (glucose/dextrose) – the filling agent that makes up almost 100% of the sweetener – mixed with a small dose of a more powerful artifical sweetener, for added sweetness.
Voilà, a package full of pure carbs, that can be labeled “zero” calories without risking a lawsuit.
The packages in fact contain almost 4 calories each, and almost a gram of carbs. While 0.9 grams of carbs may seem negligible for many people, on a low-carb diet it can matter. Especially if you use many packages a day. Ten packages equals almost half the daily carb limit on a keto diet.
So at least be aware of this. We don’t recommend these sweeteners because of the deceptive marketing. There are also lingering potential health concerns with many of these artificial sweeteners (e.g. aspartame, sucralose).
Why maltitol is not a good option
Maltitol is a sugar alcohol. It’s still the most common type used in “sugar-free” candy, desserts, and low-carb products because it’s considerably less expensive than erythritol, xylitol, and other sugar alcohols.
Maltitol is not a good choice for people on low-carb diets. About 40% of this sweetener is absorbed in the small intestine, raising blood sugar and insulin levels, especially in those with diabetes or prediabetes. It also provides about two-thirds as many calories as sugar, which is considerably more than most low-carb sweeteners.
In addition, the remaining 60% that’s not absorbed is fermented in the colon. Studies have shown that maltitol may cause significant gastrointestinal symptoms (gas, bloating, etc.), especially when consumed in amounts greater than 30 grams per day.6
Sweetness: About 80% of the sweetness of table sugar
Diet soft drinks – yes or no?
Can you drink diet soft drinks on a low-carb diet? Well, ideally you may want to avoid them. There are some clear negative effects with regular consumption, including that you’ll maintain cravings for sweet foods, and not retrain your palate to enjoy the natural, less intense sweetness of keto foods.
There’s also science suggesting that diet beverages may make it harder to lose weight, despite containing no calories.7 This could be due to hormonal effects, other effects on satiety signals, or effects on gut microbiota.
There are also other suspected, but unproven, health concerns with many of the artificial sweeteners used, like aspartame, acesulfame K and sucralose .8
However, if you feel you absolutely need to drink diet sodas, at least they will allow you to stay low carb. Regular soda, sweetened with sugar or HFCS, will very quickly result in a high carb intake, negating the positive effects of a low-carb diet.
A final word on low-carb sweeteners
While some sweeteners seem to be better than others, the best strategy for achieving optimal health and weight loss may be learning to enjoy real foods in their unsweetened state.
Although it might take a little time for your tastebuds to adapt, over time, you may discover a whole new appreciation for the subtle sweetness of natural, unprocessed foods.
Sweeteners with no calories generally do not result in weight gain when consumed in isolation or with water (in beverages). However, they could still do so if used in baked goods for example, resulting in wanting to eat more. And they do maintain people’s preference for an abnormally sweet taste, that can make it harder and less pleasurable to stick to a low-carb diet based on real foods. So our advice is still to ideally avoid them. But for weight loss and diabetes reversal, they are far less harmful than sugar.
Do you find it almost impossible to consider giving up sweet foods? You can do it. Here’s something that may interest you, our course on sugar addiction and how to take back control.
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Meal plansGet lots of weekly low-carb meal plans, complete with shopping lists and everything, with our premium meal planner tool (free trial).
For example, a packet of Splenda provides about the same sweetness as two teaspoons of sugar = 8 grams of sugar. The packet contains about 0.9 grams of carbohydrate (dextrose). That’s 0.9 / 8 = 0.11 times the effect of sugar, for an equal amount of sweetness. Pure 100% sugar has a number of 100, so Splenda gets a number of 100 x 0.11 = 11. ↩
GI = glycemic index, i.e. how quickly a carbohydrate-containing food results in a blood sugar increase after eating it. ↩
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