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Being nutrition’s number one enemy, many are trying to avoid sugar. However because most of us are used to sweet tasting foods, and prefer not to live without them.  Thus, various artificial chemicals have been invented in order to replicate the taste of sugar. These are substances that are capable of stimulating the sweet taste receptors on the tongue.  They are usually devoid of calories and we normally refer to them as artificial sweeteners as opposed to honey, sugar or maple. They do not have the adverse metabolic effect of added sugar.


These chemicals are extremely sweet and they are often added to food and drinks which are then marketed as weight loss friendly or healthy foods…. Which you would think makes sense because they are virtually calorie free.  Nonetheless, despite increased use of low calorie artificial sweeteners (and ‘diet’ foods in general), obesity pandemic is worsening.  Evidence regarding artificial sweeteners is somewhat mixed and their use is highly contentious. 


So… what is the truth about artificial sweeteners? How do they affect appetite, body weight and our risk for obesity-related chronic disease?


There are various different artificial sweeteners available and their chemical structure varies.  What they all have in common, however, is that they are incredibly effective at stimulating the sweet taste receptors on the tongue.  In fact, most are hundreds of times sweeter than sugar, gram for gram.


Some of them (such as aspartame) contain calories, but the total amount needed to provide a sweet flavour is so tiny that the calories ingested are insignificant.


Here is a table showing the most common artificial sweeteners, how sweet they are relative to sugar, and brand names they are sold under:

Other low-calorie sweeteners which are processed from natural ingredients are not considered ‘artificial’.  This includes stevia and sugar alcohols such as xylitol, erythritol, mannitol and sorbitol. Sugar alcohols tend to be as sweet as sugar with less than half the calories.  This article is about artificial sweeteners but you can read more about natural sweeteners here


Animals, including humans, don’t just seek food to satisfy energy needs.  We also seek so-called “reward” from food.  Sugary foods trigger the release of brain chemicals and hormones, part of what is known as the “food reward” pathway.  “Food reward” is crucial for feeling satiety after eating and shares brain circuitry with addictive behaviours, such as drugs.  Whilst artificial sweeteners provide sweet flavour, many researchers believe that the lack of calories prevents complete activation of the food reward pathway.


This may be the reason why in some studies, artificial sweeteners are linked with increased appetite and cravings for sweet food.  MRI (magnetic resonance imaging) shows that sugar consumption decreased signalling in the hypothalamus, the appetite regulator of the brain.  This response was not detected in relation to the consumption of aspartame. This might suggest that the brain does not register artificial sweeteners as having a satiating effect.  It is reasonable that sweetness which lack calories lead to further food seeking behaviour, adding to the overall caloric intake.  However this is not conclusive.


Another argument against artificial sweeteners is that the unnatural sweetness encourages sugar cravings and sugar dependence.  This idea is logical considering that our flavour preferences can be trained with repeated exposure.  For example, we know that reducing salt or fat over several weeks leads to a preference for lower levels of those nutrients. Sweetness is the same.


While this is not proven, it does seem to make sense. The more we eat of sweet foods, the more we want them.

Many observational studies have been conducted on artificial sweeteners.  This type of research takes a group of individuals and questions them regarding various issues such as their diet.  Several years later, they can deduct whether a particular variable (such as the use of artificial sweeteners) was associated with either an increased or decreased risk of disease.


These types of studies don’t prove anything, but they can help us identify patterns that call for further research.

Many these studies have paradoxically found that artificially sweetened drinks are linked to weight gain rather than weight loss.  However, the most recent review, which analysed the findings of 9 observational studies, found that artificial sweeteners were associated with a slightly higher BMI, but not with body weight or fat mass.  It is worth mentioning that this study was industry sponsored which doesn’t invalidate it but I always suggest to take it with a pinch of salt.  Having said that, however, correlation does not imply causation, so this can be read either way.   Luckily, the effects of artificial sweeteners on body weight has studied in numerous controlled trials (real science).


Many of these clinical trials have come to the conclusion that artificial sweeteners are favoured for weight control.  One of the largest trials looked at 641 children aged 4-11 years who had to drink either 250 ml of an artificially sweetened drink, or the same amount of a sugary drink every day for 18 months.


The children who were assigned the artificially sweetened drinks gained significantly less weight and less fat than the sugar-drinking children.  The most recent review of 15 clinical trials found that replacing sugary drinks with their artificially sweetened versions can result in modest weight loss of about less than 1kg on average.  So best case scenario, artificial sweeteners appear to be mildly effective for weight loss.  They certainly don’t seem to cause weight gain, at least not on average.


Nonetheless, there’s more to health than just a narrow approach of weight loss.  For example, there are some observational studies linking artificial sweetener consumption to metabolic disorders.  This includes an increased risk of metabolic syndrome, type 2 diabetes and heart disease.  At times such results are quite astounding… for example, one study established that diet soft drinks were linked to a 121% greater risk of type 2 diabetes. Yet another study found that these drinks were linked to a 34% greater risk of metabolic syndrome.  This is supported by a recent prominent study on artificial sweeteners, showing that they caused a disruption in the gut flora and induced glucose intolerance.  Bacteria in the intestine (gut flora) are incredibly important for health.  The likelihood that artificial sweeteners may be causing disruption in the gut bacteria is undoubtedly a cause for concern.


The bottom line is that replacing sugar with artificial sweeteners may be helpful in reducing body weight, but only slightly at best.  Their consumption does not appear to cause weight gain, at least not in the short-term.


At the end of the day, artificial sweeteners are not as “toxic” as some people make them out to be, but I’m not convinced that they’re perfectly safe either.  The jury is still out on this issue so you need to decide for yourself. 


If you’re healthy, happy and satisfied with the results you’re getting and you are an artificial sweeteners user then there’s no need to change anything. If it is not broken, don’t fix it.  But if you suffer from cravings, poor blood sugar control or any unidentified health problem, I would recommend that avoiding artificial sweeteners may be one of many things to consider.


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