#227 Do Artificial Sweeteners Really Cause Weight Gain?

Do Artificial Sweeteners Really Cause Weight Gain?

Once again, artificial sweeteners dominated the medical news this week.  This time it was from a study suggesting that artificial sweeteners might cause weight gain and heart disease.  In this article, I’ll dissect the latest research and offer a practical approach to artificial sweeteners.

The Latest Artificial Sweetener Study

I really liked the quality of this latest study.  The researchers did a great job of trying to make sense of every study that has ever been published about artificial sweeteners.

While most health conscientious people consider artificial sweeteners as harmful, the health food industry has gravitated to stevia as a “healthy” alternative.  Fortunately, this study also included stevia.

To make sense of every credible artificial sweetener study that has ever been published, researchers divided these studies into two groups.  The first group consisted of randomized controlled trials or RCTs.

RCTs are considered the very most accurate type of a medical study you can do.  In RCTs, researchers randomly divide the participants into two groups.  This way, you can minimize confounding factors that might give you the wrong results.  In this study, researchers included 7 RCTs involving a total of 1,003 people who were then followed closely for an average of six months.

In contrast, this study also reported the results of 30 observational studies involving 405,907 people who were followed for an average of 10 years.  While these observational studies aren’t very accurate, they can raise questions about the long-term safety of artificial sweeteners.

What Do RCTs Tell Us About Artificial Sweeteners

From the 1,003 people included from seven randomized controlled trials (RCTs), this study reported that when it comes to weight gain, artificial sweeteners are neutral.  In other words, they don’t cause people to gain or lose weight.

Interestingly, when you look at all the studies published from the artificial sweetener companies, these studies almost always show that people lose weight.  However, when you look at studies that are not sponsored by artificial sweetener companies, there generally is no weight loss from artificial sweeteners.

Thus, if you can’t give up your daily Diet Coke habit, then you can hold fast to the results from RCTs.  At least when you look at the health effects of artificial sweeteners out to six months, they don’t appear to cause weight gain.

However, because RCTs are very costly to do, follow up periods tend to be very short.  Thus, with this average follow up of just six months, it is impossible to know if artificial sweeteners put you at risk for other diseases, like diabetes or heart disease.

As you know, most people don’t just drink Diet Coke for six months.  Rather, they tend to drink it over a lifetime.  This is where the less accurate but long-term observational studies can be helpful.

What Do Observational Studies Tell Us About Artificial Sweeteners?

While artificial sweeteners, including stevia, looked relatively harmless in the six month long randomized controlled trials (RCTs), the results were quite frightening when you look at the 10 year observational studies.  Indeed, the 30 observational studies involving 405,907 people paint a completely different picture of artificial sweeteners.

The observational studies clearly linked artificial sweeteners to weight gain over time. Not only do these studies report weight gain but they also show that artificial sweeteners may increase your risk of diabetes by 30%!

If diabetes wasn’t frightening enough, these observational studies also report a 13% increased risk of high blood pressure, a 26% increased risk of a stroke, and a 32% increased risk of heart disease!  Clearly, these are all conditions that will shorten your life.

Do You Believe the RCTs or Observational Studies?

So which studies do you believe?  Do you believe the very accurate six month small studies which show that artificial sweeteners don’t seem to pose much risk or do you believe the less accurate 10 year long big studies which link artificial sweeteners to many scary diseases?

The truth is that when it comes to your health and longevity, we just don’t understand the long-term effects of these chemicals.  Even the “healthy” stevia didn’t do any better than the other artificial sweeteners in this study.

While artificial sweeteners might be “less bad” for you than sugar, that certainly doesn’t make them health foods.  When I try to put our “modern foods” into perspective, I like to think about what they would do in Longevity Village.

Artificial Sweeteners in the Longevity Village Diet

It probably goes without saying that you’d be hard-pressed to find a can of soda on a Longevity Villager’s dinner table. Largely because of advertising we’ve been exposed to since childhood, not to mention the addictive combo punch of sugar and caffeine, a lot of people have convinced themselves that their Coke-a-day habit is little more than a minor health indiscretion.

In fact, just a single can of soda pop each day can put you at greater risk for diabetes, heart disease, obesity, and overall poor health. If there was an illegal drug that did all these things, we’d call it a menace to society. But because so many of us associate fizzy drinks with the frivolity of childhood, we treat a global health scourge like a treasured friend.

My “buddy drink” was Diet Coke. And while I never assumed it was healthy, I justified my habit by telling myself that it was healthier for me than a regular soft drink. After all, Diet Coke doesn’t have any sugar. And that, I figured, meant it was “less bad.”

Magan, one of the village centenarians we met in our recently published book, The Longevity Plan, was the one who put “less bad” into perspective for me. “If something is bad it is bad,” she said. “Even if the damage is not very much right now, it builds up over time. These are the most dangerous kinds of habits.”

When we make the switch from regular sodas to so-called diet drinks, we might be abusing ourselves a tad less, but we’re not actually doing ourselves any good. What’s worse, because we feel as though we’ve taken steps toward a healthier life, we’ve slowed and sometimes halted progress toward the elimination of unhealthy consumables, which should, of course, be our ultimate goal.

Of course, all of this is assuming that diet drinks are, in fact, less bad for us. And while some would say so the jury is still deliberating on that question, I’d argue we haven’t even finished the trial yet. We’ve been studying artificial sweeteners for more than 140 years, but every year researchers discover something new. What we do know, though, is that these substances may have a similar effect on our metabolism and gut flora as high fructose corn syrup.

Such findings shouldn’t really be that surprising. Most artificial sweeteners are hundreds of times sweeter than natural sugar. When we expose our bodies to such extremes, we should expect extreme reactions.

That’s not just a lesson when it comes to drinks. There’s simply no extra sugar in the traditional village diet. There are so many foods out there that already pack a sweet punch in their natural state. Because villagers include these foods with almost every meal, they’re simply less inclined to seek out even more sugary foods.

Do You Want to Learn More?

Do you want to learn more about how to free yourself from medical conditions?  If so, be sure to pick up a copy of our number 1 Amazon best selling book, The Longevity Plan.  This book summarizes everything I have learned from my own health journey and will help you to enjoy great health to age 100!

Until next week’s article, what is your take on artificial sweeteners?  Have you found them hard to give up?

Please leave your thoughts and questions below.  I’ll do my best to quickly respond to every question posted.  Also, if you haven’t yet signed up for my free weekly newsletter and podcast, now would be a great time.

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  1. I’m disappointed to see Stevia lumped in with artificial sweeteners. While it’s true it does go through a manufacturing process, it would be hard to use in its raw form.

    Would a product like the tan color Sugar in the Raw be a “more natural product” as in a little closer to natural than the process that the Stevia plant undergoes?

    Also, does the fact that Stevia is many times sweeter than cane sugar have a bearing on glucose levels? I can use a 1/4 of a teaspoon of Stevia in my coffee and it will have the same effect as two full teaspoons of cane sugar. But, taste of sweetness aside–which puts the higher impact on you glucose level?

    Thanks , I enjoy your emails.

    • Hi Ben,

      Great questions. I, too, was disappointed to see stevia lumped in with the other artificial sweeteners. That said, I personally have been off of all sugar now for several months. I do enjoy a little stevia in my dark chocolate.

      While every study points to sugar as a problem for just about everything, the medical studies on stevia are mixed. Most seem to not indicate a problem with stevia. This is especially true for people suffering from diabetes.

      Hope this helps!


  2. Artificial Sweeteners do not cause weight gain! I believe my own 30 year experiment
    with it. I have had diabetes type 2 for 30 years, that is the reason for the experiment. I have been able to take off 55 lbs and keep it off for many years using
    Splenda. The problem for people is not the artificial sweetener, but their lack of
    understanding of food and how it affects their blood sugar and weight. Anything made from flour, potatoes and rice (all high starch) are seen the same way by the body. They quickly turn into glucose in the blood just like sugar and they cause weight gain around the middle just like sugar.

    People make foods with an artificial sweeteners and flour and more than likely feel justified in eating eat more of it because it has no sugar. The flour itself is a form of sugar for the body.

    • Hi Rosalie,

      Thanks for sharing your experiences! Your personal experience fits very nicely with the randomized controlled trials on artificial sweeteners.

      Your points are well taken. This is probably one of many reasons why observational studies on artificial sweeteners, or anything else, should be taken with the proverbial “grain of salt.”

      Warm regards,


  3. Unfortunately, the linked article was a bit lacking on details. I notice that they lump all sweeteners together, but I’ve seen some studies recently that suggest that stevia has a lower impact on insulation release. (As a type 2 diabetic this has been a concern for me.) I was wondering what your take on that would be. (Not that I use much diet sweetener either way…but did just get some dark chocolate with stevia in the mail today!)

    • Hi John,

      Thanks for reading! I completely understand here you are coming from. And, by the way, I also like dark chocolate sweetened with stevia.

      The studies on stevia are mixed. Overall, it seems as if stevia might be better than other artificial sweeteners. However, in this analysis, the stevia studies the researchers included didn’t fare so well. Thus, they chose to lump them all together.

      My personal take on artificial sweeteners is to minimize them as much as possible and if I do use an artificial sweetener my preference is stevia.

      Hope this helps!


  4. Great article Dr. Day. As an associate professor of nutrition at the U of U School Dentistry, I really appreciated your analysis of the myriad of research on artificial sweeteners. For sure a little bad is still bad and over time even a little bad is even “badder.” People do not always like the truth about bad habits, and the proverbial diet Coke is a world wide bad habit.

    Do you have a comment on the best way sweeten your oat meal, if you didn’t want to even use Stevia?

    Also, were these studies able to separate out different dietary lifestyles to determine if over time it wasn’t a “crappy” diet rather than just the artificial sweeteners that resulted in the data regarding other chronic disease.?

    Also, as an associate professor of nutrition, in keeping my lectures current and up to date, I have read over the last several years about every book on nutrition out there. There are two I have at the top of my list. One just recently made my top two list (if my opinion is worth anything that is). They are Dr. Campbell’s recent updated and revised edition of the China Study, and the other is your book which I just finished reading. Great Book. Thank You. My personal titles for both of them are, and I know you will appreciate this, “The Unbridged Versions of the 89th Section”

    Sometime in the future I will be imposing upon you a request for next spring to come up to the Dental School, and speak to the four classes here at the dental school.

    Barry Packer, DDS

    • Hi Barry,

      Thank you so much for reading and for your thoughtful reply! I would be honored to speak at your dental school.

      You are absolutely correct, nutritional studies are so very hard to do. Ideally, they would all be randomized controlled trials. As soon as you bring in observational studies then all the biases you mention, as well as countless others, all enter in…

      While I am trying to cut back on my own use of artificial sweeteners, when I do choose to use them my preference is stevia. While stevia didn’t do so well in this study, other studies suggest that it may be better than the other artificial sweeteners.

      Warm regards,


  5. What do we know about Stevia, it comes from a plant, I thought this was the best alternative to artificial sweeteners?

    • Hi Shannon,

      You are absolutely correct, stevia does come from a plant. In my mind it is probably a better alternative than the other artificial sweeteners.

      The challenge is that the way most people use stevia, myself included, is in a highly processed form which is far from the original plant…

      While stevia didn’t fare so well in this study, other studies suggest that it may not have the same effects as the other artificial sweeteners.

      Hope this helps!