The use of artificial sweeteners has dramatically increased in the last decade due to the common perception that they are beneficial for weight loss. However, the medical evidence we have is extremely controversial and many studies have revealed that the increased consumption of these food additives correlates with the rise in obesity cases worldwide.
The fact that artificial sweeteners are so ridiculously sweet-tasting and at the same time provide no-calories is without doubt extraordinary, but recent research has shown that they may be as bad as sugar-containing products. All artificial sweeteners are calorie free as they are not metabolised by the body and so are excreted unchanged. However, aspartame is an exception to this rule as it is metabolised and as a result provides some calories (4Kcal/g). However, since aspartame is 200x sweeter than sugar only very small amounts are added and so the calorie count is insignificant. All of this seems excellent for weight loss or diseases like diabetes, but the truth is that these sweeteners mess-up with the brain’s perception of taste and can indirectly affect insulin production.
Figure 1. Artificial sweeteners are hundreds to thousands of times sweeter than natural sugars and they are also calorie free. From http://caravel.sc.edu/2012/09/artificial-sweeteners-on-weight-loss/
Several observational studies have shown positive correlations between artificial sweetener consumption and BMI. In simple words, people that consumed greater amounts of these food additives were more likely to be obese than those ingesting smaller quantities. The San Antonio Heart Study investigated the effect of diet on the risk of obesity and cardiovascular disease in 3682 adult subjects. It was seen that individuals who consumed 3 or more artificially sweetened beverages had a significantly higher BMI than control subjects who drank unsweetened drinks.
Additionally, a 12 year follow-up investigation in the UK revealed that individuals who consumed two or more serving of artificially sweetened diet soft drinks were at greater risk of developing coronary heart disease and kidney failure compared to those that consumed 1 or fewer drinks. Since artificial sweeteners are not broken down, the kidneys have to work harder to eliminate them and this could potentially increase the likelihood of renal disease in the long-term.
Figure 2. Several observational studies have revealed a positive correlation between artificial sweetener consumption and obesity. Additionally, other researchers have shown that people that rely too much on these food additives are at greater risk of developing diabetes, kidney and heart disease.
But the big question is how can these sweeteners increase the incidence of obesity and diabetes if they don’t contain any calories. One good explanation that is backed by experimental evidence is that many individuals that use artificial sweeteners have poor quality diets and they typically eat too much. Scientists have shown that artificial sweeteners can lead to sugar craving and dependence due to the simple fact that they are excessively sweet. However, it is also speculated that the fact that the body tastes something sweet without getting any calories makes the person more hungry and likely to eat extra food. Several experiments in humans have shown that these sweeteners increase appetite to a greater extent than natural sugars, making individuals more likely to overindulge. A group of scientists investigated hunger ratings in a group of individuals that were either given aspartame, glucose or water. They found that those that were given aspartame were more hungry than those who consumed glucose or water.
Meanwhile, a very interesting experiment revealed that the appetite-promoting effects of artificial sweeteners differed on their method of administration. In this investigation, only the subjects receiving aspartame-sweetened water but not aspartame capsules, reported an increase in appetite (figure 3). This provides evidence that the sweet perception of artificial sweeteners at the level of taste receptors in the mouth is required to increase hunger, but their direct administration to the stomach in capsule form does not have an effect. Obviously the purpose of these food additives is to enhance the flavour of food/drinks, so everyone consuming them will inevitably activate their taste receptors and will feel hungrier than if they were consuming natural sugars.
Figure 3. In an experiment, scientists compared how hungry individuals felt after they were either given aspartame dissolved in water or in capsule-form. The results showed that individuals who consumed aspartame-sweetened water had an increase in appetite, whereas those given the capsule reported no effect in hunger scores.
At the levels of the gut, artificial sweeteners have been demonstrated to increase the release of Glucagon-like petide-1 (GLP-1) before glucose administration in both humans and animal models. GLP-1 is a hormone produced by the body that causes insulin secretion and gastric emptying (figure 4). This finding is of vital importance as it shows that consuming artificial sweeteners in conjunction with sugar-containing foods/drinks or even high glycemic index carbohydrates may lead to faster glucose absorption into the bloodstream and a more aggressive insulin response. Over time this may lead to glucose intolerance, obesity and the development of type 2 diabetes.Figure 4. a) Researchers have found that consuming artificial sweeteners along with sugar-rich foods stimulates b) GLP-1 production. c) This is turn increases insulin production and affects gastric emptying so that carbohydrates and sugars are absorbed and taken into cells faster than they should. d) It is speculated that this may lead to metabolic complications such as diabetes and obesity (e) on the long-run.
All of this doesn’t mean that eating sugar is a better option than artificial sweeteners or the other way round. The answer is that both are bad and should be limited or preferably avoided in the diet. Studies have shown that individuals who consume many sweetened drinks have an increased risk of obesity and diabetes (quite obvious), but those drinking artificially sweetened beverages share a very similar risk.
Overall, artificial sweeteners can be a good choice if they are used to replace a bit of sugar from the diet (to sweeten tea or coffee) and then you don’t eat any sugary foods besides whole fruits. However, the real problem is that many people use these sweeteners as an excuse to eat more foods they don’t even realise are loaded with sugars and calories. This not only leads them to gain weight, but body fat begins to accumulate at vital organs, increasing the risk of diabetes and other metabolic conditions.
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