Non-nutritive sweeteners and its effect on metabolism
When starting with your new low carbohydrate, healthy fat lifestyle, we might initially struggle to leave the sweet-tasting foods behind. Sometimes you imagine gulping down a bottle of cooldrink when actually it is just your plain third bottle of water. When doing grocery shopping you find these colorful labels marketing that it is sugar-free and is often available from cooldrinks, chocolates, etc. and you might think “What? Yes, take everything, it is sugar-free after all!”. It seems like it should be fine consuming all these sweetened foods and beverages, but is it really? It is important to have a look at the different types of sweeteners and what they can do to the body.
Types of sweeteners and sugar substitutes
Products that contain sweeteners are mostly sugar-free candy, chocolates, gum and cooldrinks. Look out for names such as Stevia, Sucralose, Xylitol, Isomalt, Erythritol, Sorbitol, Aspartame and Acesulfame K. Three sweeteners considered safe when following a low carbohydrate, healthy fat lifestyle, are Stevia, Erythritol, and Sucralose (but only in moderation and if well-tolerated).
Many products contain Stevia, a natural sweetener made of the plant called Stevia rebaudiana . It’s considered a non-nutritive sweetener, which means that it contains little to no calories or carbohydrates .
Erythritol is made by fermenting a variety of glucose with the natural microorganism Moniliella pollinis. Its sweetness comes from non-digestible carbohydrates similar to those that you would find in fruit. Your body can’t absorb these, which is why they don’t have any adverse effects on your gastrointestinal system .
Sucralose is an artificial sweetener that is not metabolized in the body, meaning it passes through your body undigested and thus does not provide any calories or carbohydrates. Some studies have found that sucralose could produce harmful compounds when exposed to high temperatures and is therefore not suitable for cooking purposes .
Even though most of the sweeteners are low in carbohydrates, they contain chemicals that might increase blood sugar and insulin levels, the exact opposite of what you want when trying to stay in ketosis and reverse insulin resistance. The sudden increase in blood sugar and insulin levels can worsen sugar cravings, making it harder to stick to your low carbohydrate lifestyle .
Here is a few sugar substitutes that you want to avoid completely when following a low carbohydrate lifestyle: white sugar (including powdered or confectioner’s sugar), all varieties of honey, maple syrup, high fructose corn syrup, golden syrup, coconut palm sugar, coconut sugar, brown sugar, aspartame and sugar alcohols .
Sugar alcohols like xylitol, glycerol, sorbitol, and mannitol might seem like a good replacement for sugar, but they are not created equal. Some sugar alcohols can take your body out of ketosis and can cause cravings. Sugar alcohols (polyols) are a natural sugar found in many foods, for example, fruits, and are used to sweeten “sugar-free foods”. When compared to regular sugar, some have the same amount of calories and carbohydrates as sugar .
Another concern of sugar alcohols is the effect on the gastrointestinal system. Xylitol has been associated with digestive problems such as abdominal cramps, nausea, and diarrhoea when used in large quantities, so it might be a good idea to start with a small quantity and increase when well tolerated. The use of xylitol should be stopped when any adverse effects are experienced .
Metabolic effects of sugar and sweeteners on the body
Blood sugar and insulin levels
When we consume sugar, it moves from the gastrointestinal system into the bloodstream, causing our blood sugar levels to rise. The pancreas secretes hormones, such as insulin, into the blood to help regulate our blood sugar levels. Certain studies suggest that some artificial sweeteners may impact blood glucose levels, or/and insulin levels. Thus, when following a low-carbohydrate lifestyle to lower insulin resistance, a high intake of sweeteners can counteract these efforts. For example, a study conducted in 2016 showed that the consumption of artificially sweetened beverages on a daily basis by pregnant mothers was associated with a 2-fold higher risk of infants being overweight at 1 year of age .
The gut microbiota (microorganisms in our digestive system) help break down the food we eat. The gut microbiota reacts differently to artificial sweeteners compared to real sugar. These microorganisms become less able to break down real sugars the more that they are exposed to artificial sweeteners. When the microbiota is not able to break down sugars efficiently, it can affect the amount of nutrients we are able to absorb from the foods that we eat, leading to vitamin and mineral deficiencies even when eating the correct foods .
Receptors in brain “tasting” sweetness
Even though our brains and bodies process real and artificial sugars in a different way, the sweetness of any kind increases the brain’s tolerance and desire for sweetness. This simply means that the more sweet things we consume, the more you will have to eat in order for your brain to know that something is sweet. Craving sugar because the brain has become tolerant of sweetness is an unwanted symptom that can lead to overconsumption, which can then lead to unintended weight gain .
Although it might seem like a good idea to consume sweetener-containing products rather than regular sugar, it might have adverse effects on your insulin sensitivity, the ability to efficiently absorb nutrients from the gut as well as causing tolerance to sweetness as perceived by the brain. For this reason, sweeteners should be used in moderation and only if tolerated by the body. Instead of replacing the usual starchy foods like bread and biscuits with a “sugar-free” option, forget about the need for starches and focus on eating natural fresh whole foods!
- The Keto Summit. Louis Hendon [Internet]. Is Erythritol Keto? Available from: https://ketosummit.com/keto-sugars/
- Healthline. Rachael Link [Internet]. The 6 Best Sweeteners on a Low-Carb Keto Diet (And 6 to Avoid) Available from: https://www.healthline.com/nutrition/keto-sweeteners
- Jane Shearer. Artificially sweetened taste of insulin resistance? NRC Research Press. 2019. Available from: https://www.nrcresearchpress.com/doi/pdfplus/10.1139/apnm-2016-0294
- Frontiers for Young Minds. Michael Hout [Internet]. Trick or Treat? How Artificial Sweeteners Affect the Brain and Body. 2019. Available from: https://kids.frontiersin.org/article/10.3389/frym.2019.00051