4 Myths You Have Been Told About Artificial Sweeteners

Brad Dieter
Written By: Brad Dieter
April 11th, 2018
Updated: June 13th, 2020
Categories: Articles Nutrition
13.1K Reads
4 Myths You Have Been Told About Artificial Sweeteners
A lot of folks truly fear artificial sweeteners, but most of what you've heard about them are myths. Separate fact from fiction by reading this article.

“Then the LORD rained down fire and burning sulfur from the sky on Sodom and Gomorrah”. Genesis 19:24

That is how I feel every time I Google the words “artificial sweeteners”.


The amount of craziness, vitriol, and gnashing of teeth surrounding this topic is astounding.

I for one am not a big fan of all the hyperbole and angry shouting about these topics. I prefer looking at the science and making rational conclusions.

So that, my friends, is what we are going to do today.

We are going to cut through the noise and let you in on the truth behind 4 myths that you have been told about artificial sweeteners.

1. Artificial Sweeteners Make You Fat

As humans we like to blame things for making “us” gain weight. I mean look at every diet book over the last 30 years, each of them picks something to blame and says, “AHA! X is to blame, remove X and your entire universe will be perfect”.

Related: Misunderstood Macros - 10 Lies You've Been Told About Carbohydrates

Seriously, this is what we see time and time again.

Artificial sweeteners have not been spared this fate either.

Headlines of artificial sweeteners making you fat are readily abound.

Good thing for us we have conducted a lot of studies directly examining the effect of artificial sweeteners on weight gain.

In one study, 41 overweight people were given sugar sweetened supplements or artificially sweetened supplements and asked to consume their normal diet. Over the course of 10 weeks the sugar sweetened beverage group gained 1.6 kg, of which 1.3 kg was increased fat mass; the group that consumed the artificial sweetener had no real change in body weight of fat mass1.

Artificial Sweeteners in a cup

That study is not the only one to show this, in another study of 30 people, people were given soda sweetened with high-fructose corn-syrup or aspartame (this is basically like given people Coke and Diet Coke) for 3 weeks. In this study, the sugar sweetened beverage caused people to gain weight while the soda sweetened with aspartame caused people to lose weight2.

In a seminal paper published in the New England Journal of Medicine (The Mac Daddy of medical journals), 641 children aged 4 through 11 were randomly assigned to consume either artificially sweetened beverages or sugar sweetened beverages.

Over the course of 18 months, the kids in the sugar sweetened beverage group gained more weight, had higher skin fold measurements (surrogate for body fat), and greater increase in weight circumference3.

It also appears that when changing dietary habits during and after weight loss artificial sweeteners are more helpful than regular sweeteners in terms of maintaining weight loss4.

So overall, in intervention studies it looks like artificial sweeteners, specifically in the form of diet soda’s do not cause you to gain meaningful weight.

2. Artificial Sweeteners Are Worse Than Sugar

It’s common belief that artificial sweeteners are worse than sugar since they spike insulin, but have no calories.

Where does one even begin with this one… I think by diving right into the data as wasting time waxing and waning philosophically about this is much less compelling than the actual science.

Here we go.

Initial studies from 1998 showed that when aspartame was directly applied to the cells that produce insulin it did nothing in terms of insulin release. Nada. Zilch. Nine. Nunca5. However, when you added it with glucose it appeared to result in a small “accelerator” effect, increasing glucose’s insulinogenic response.

Ok, cool: that is just cells in a dish, which, while cool, are not humans and a little bit lame.

Onto human data.

In 2009 a study was published where people were fed either carbonated water, or diet soda. Overall, the diet soda had a very minor (not statistically significant) increase in insulin release, which was for all intents and purposes no different than the carbonated water6. Interestingly, the diet soda increased secretion of the protein glucagon-like peptide 1 which plays a role in hunger and glucose metabolism.

Related: Carbs Aren't Making You Fat - The Truth About Insulin

So to put a bow on this, it appears that most artificial sweeteners don’t really cause crazy insulin spikes. So we can cool our jets a bit on that one.

3. Artificial Sweeteners Will Ruin Your Microbiome

There is some speculation and concern that artificial sweeteners might change your microbiome. Furthermore, there have been a lot of speculations that changes to the microbiome might cause you to gain weight (this is really unknown in humans and recent studies indicate it might not be true).

There are some things we should know about this though as it is very important we understand this idea.

In mice, it has been shown that artificial sweeteners at moderate to really high doses can cause bad changes to the microbiome and that this can cause a form of “glucose intolerance”7. Now it is important to note that not all of the artificial sweeteners tested caused this effect, and sucrose itself caused the same phenomenon.

Furthermore, this data has not been replicated to a meaningful degree in other mice nor has it been shown in humans. In fact, a thorough search of the actual evidence in humans yields the same result as I got when I asked a girl to homecoming my Junior year… a big goose egg (it happens to us all…).

So what we can say is that there is some evidence in rodents that some artificial sweeteners might change our microbiome, but we have no real idea if that happens in humans, how much it takes, what kind it takes, and what the end consequences of it are.

Artificial Sweeteners in a Glass Container

4. Aspartame is Poisonous

People love to hate on Aspartame.

They often even go so far as to call it a “poison”.

Well, once again we can look to science and the actual evidence to tell us if it is a poison, and if so, at what dose.

Aspartame gets metabolized into methanol, which is bad and makes you go blind8. It is believed that the reason methanol is toxic and has these effects is because large amounts of methanol gets metabolized into formate, which is the molecule that does the damage.

So for aspartame to be poisonous you have to convert aspartame to high quantities of methanol and then to formate. Well, that study has been done and it was pretty legit.

30 people were given doses of aspartame at the 34 mg/kg (the high end of normal intake), 100 mg/kg, 150 mg/kg, and 200 mg/kg. This is the equivalent of drinking roughly 12 to 80 cans of diet soda per day.  In the 34 mg/kg dose, methanol levels were undetectable, but were detectable in the 100, 150, and 200 mg/kg doses.

However, no formate was detectable, even in the highest level of aspartame group9. There was also no issues seen with any other blood marker or eyes upon an eye exam.

Outside of this, there are no other well-known or studied aspects of aspartame being poisonous.

The Wrap Up

Based on the interventional data, artificial sweeteners do not make you gain weight. In fact, they might help you lose weight and keep weight off.

They don’t appear to have any major insulinogenic properties on the whole.

There is very limited evidence that some of them, in pretty substantial doses, change the microbiome in rodents, but this has not been proven in humans.

In doses 99.9999999% of us could possibly consume, it does not appear to be toxic.