How Safe Are Artificial Sweeteners? Are They Really Causing Obesity and Diabetes?

Transformational Nutrition artificial sweeteners

For many, low calorie sweeteners play a very important dietary role – they allow us to consume sweet tasting food and drinks with virtually no calories. There is, however, much controversy surrounding the safety of sweeteners which means they are barely out of the news these days.  For example, the Daily Mail recently stated that ‘artificial sweeteners still cause obesity and diabetes’.  This is rather a bold statement to make in light of the actual evidence, let’s look at why.

Observational data

Yes, it is true that observational studies have revealed an association between the consumption of  low calorie sweeteners and higher BMI but there is something you need to understand about these studies, they are not clinical or scientific.  They take a section of the population, look at their habits and then draw conclusions that simply cannot be linked to causation.  In other words, just because someone drinks diet soft drinks does not mean that we can conclude that the sweeteners are the cause of them having or developing obesity, we can merely make a link.  But think about it, if someone is overweight what is one of the first things they may do to try and lose weight?  Swap their sugary, calorific drinks to diet versions.

Observational studies do not correlate with causation; do dieters simply choose diet drinks more?

Clinical Research

That brings me on nicely to what the scientific research actually does suggest.  A recent meta-analysis of 15 Randomised Controlled Trials (robust, clinical trials that can be linked to causation) showed that participants who swapped their caloric sweeteners (sugar etc) with low calorie sweetener alternatives actually saw a significant reduction in BMI, fat mass and waist circumference – a key indicator of metabolic disease risk.  It would therefore seem that replacing sugar with sweeteners actually has a real health benefit for those who are overweight or have diabetes.  The most important factor in helping to reduce mortality risk is to maintain a healthy weight and for many, low calorie sweeteners are a very practical way of doing so.

Low calorie sweeteners can be a very effective tool in weight management.

Real cause of obesity 

Transformational Nutrition sweeteners obesityThe key issue that many media articles, written by unqualified journalists, often seem to skip over is the fact that obesity is predominantly caused by an excess consumption of calories and sedentary lifestyle.  If you eat more than your body requires, then you will be pushed in to an positive energy balance that inevitably causes weight gain, as my article here explains.  As your weight increases, so does your BMI and waist circumference which puts you at a higher risk of a number of serious, life diminishing diseases.

An excessive consumption of calories is the primary cause of obesity.


Type 2 diabetes is one of these diseases.  Another key issue that the Daily Mail article, in particular, failed to raise is the difference between Type 1 and 2 diabetes.  Whilst we can link Type 2 diabetes to obesity and generally poor lifestyle choices, the causes of Type 1 are still unknown.  We do know that genetics and environment play a part in its development, but it has not been linked to obesity in the same way that Type 2 diabetes has.

Type 1 and Type 2  Diabetes should not be confused.  Only 5-10% of the population have Type 1.

Are all chemicals really so bad?

Transformational nutrition sweeteners chemicalsAnother way that the media has portrayed sweeteners in a such a poor light is through their play on the fact they are chemicals.  The word ‘chemical’ has been demonised, misrepresented even.  WE ARE ALL CHEMICALS, the air we breath is chemicals, water is a chemical.

It is indeed true that not all chemicals are good for us and even those that are, such as water or fluoride, can be harmful if we are exposed to them too much.  But deeming all chemical as toxic is misleading.  Just as claiming that all natural chemicals are OK whilst man-made ones are not is untrue.  Some of the most toxic chemicals known to man are natural.  Tetanospasmin, for example, is a neurotoxin produced by bacteria that causes Tetanus.  And Palytoxin, which is found in marine life, narrows the blood vessels, particularly large arteries.

Whereas, sometimes, synthetic chemicals can actually be better for you.  Synthetic melatonin supplements, for example, are safer than those naturally derived which are at risk of containing viral material. Whilst some synthetic chemicals are more environmentally friendly; the vanilla bean is becoming depleted for instance so synthetic versions may be preferential.

Here is the chemical make up of the sweetener aspartame:

N-L-aaspartyl-L-phenylalanine-l-methyl ester (APM)

Now compare this with those found in blueberries:

Transformational Nutrition chemicals blueberries

I will leave you to decide which one is full of chemicals….

How well do we metabolise sweeteners?

One of the key benefits of artificial sweeteners is their intensely sweet taste which means that we only need a very small amount to make things taste good.  In fact, Splenda is 600 times sweeter than sugar!  Therefore, as we only need to consume small quantities at a time, they are easy for our bodies to digest.  A recent review has highlighted this as quoted below:

  1. Saccharin, acesulfame-K (Ace-K), and sucralose do not undergo digestion in the gastrointestinal tract following consumption. All are quickly eliminated from the body with no accumulation.

  2. Aspartame and steviol glycosides (stevia) both undergo changes within the digestive tract, and the resulting products are absorbed. Aspartame is completely digested to its component parts, all of which occur in the diet, and so utilised by the body in exactly the same way as the same components in other foods. Steviol glycosides are partly digested by the gut microflora, to stevia which is absorbed, metabolised by the liver, and excreted in the urine.

They have therefore been deemed as safe consume as part of a healthy diet.

Furthermore, there is absolutely no scientific evidence in human beings to suggest that sweeteners cause cancer.  In fact, saccharin has been removed, by the FDA, from the list of possible carcinogens.

Transformational nutrition research in ratsThere has, however, been some early research to suggest that sucralose, a type of sweetener, can decrease the beneficial gut bacteria in rats.  It is important to note that this is very early research and it has only been conducted in rats; humans are not rats!  So, whilst it is worth bearing in mind, we can not draw any conclusions to date.  It may be prudent, however, to ensure that if you do consume sweeteners, you do so in moderation.

Most clinical research on sweeteners as been carried out in rats; humans cannot be compared with rats.


It is true that we still have much to learn about sweeteners and their effect on the human body.  Yet to make claims that they are the cause of obesity, or any other disease for that matter, is simply untrue and scaremongering.  If anything, they can be a very useful way of preventing weight gain, obesity and Type 2 diabetes for many people.

I will leave you with this quote from a 2006 study:

Using foods and drinks sweetened with aspartame … is an effective way to maintain and lose weight without reducing the palatability of the diet.

This was brought to you by Rebecca Flannery, Evidence Based Nutritionist at Transformational Nutrition.