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What 7 Studies Say About Artificial Sweeteners and Weight Loss

What 7 Studies Say About Artificial Sweeteners and Weight Loss

If you want to know if artificial sweeteners are helping or hurting your weight loss efforts, and what to do about it, then you want to read this article.

These days, we’re told that just about everything can automagically make us gain weight.

You know…

Different diet “gurus” have different dogmas, but they all share the same fundamental philosophy:

That you have to “eat clean” to get lean, and that weight gain is caused by eating the wrong foods.

Well, they’re absolutely wrong—weight gain isn’t caused by what you eat but how much—but that’s another discussion.

We’re here to talk artificial sweeteners and weight loss, which is an equally controversial subject.

These chemicals contain far fewer calories than traditional sweeteners like sugar and honey, which led researchers to believe that their widespread adoption should curb obesity rates.

Well, it hasn’t. We’ve just gotten fatter and fatter.


Are artificial sweeteners contributing to the obesity crisis? Can they somehow make you fatter, or at least more likely to gain weight?

Let’s find out…

What Are Artificial Sweeteners?

splenda weight loss

Artificial sweeteners are manmade chemicals added to foods to make them sweet.

They work by triggering the “sweetness receptors” on your tongue in the same way as sugar.

There are two major differences between them and sugar, though:

  1. They’re much sweeter.
  1. They aren’t digested and absorbed in the same way, making them much lower in calories.

Here’s a quick summary of the most popular artificial sweeteners in the US and EU:

  • Aspartame

Aspartame is 200 times sweeter than sugar. The branded products Nutrasweet, Equal, and Sugar Twin are aspartame.

  • Acesulfame potassium

Acesulfame potassium is also known as acesulfame k or Ace K, and it’s 200 times sweeter than sugar. The branded products Sunnet and Sweet One are Ace K.

  • Advantame

Advantame is 20,000 times sweeter than sugar.

  • Aspartame-acesulfame salt

Aspartame-acesulfame salt is 350 times sweeter than sugar The branded product Twinsweet is aspartame-acesulfame salt

  • Neotame

Neotame is 13,000 times sweeter than sugar. The branded product Newtame is neotame.

  • Saccharin

Saccharin is 700 times sweeter than sugar. The branded products Sweet’N Low, Sweet Twin, and Necta Sweet are saccharin.

  • Sucralose

Sucralose is 600 times sweeter sugar. The branded product Splenda is sucralose.

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Can Artificial Sweeteners Make You Gain Weight?

aspartame weight loss

The short answer is, no, artificial sweeteners can’t directly cause you to gain weight.

They just don’t contain enough calories to move the needle.

But what about indirectly?

Can eating artificial sweeteners somehow, through various trickle-down effects, make you gain weight, or at least make you more likely to gain weight?

Well, that’s a deeper question that requires a deeper answer.

Concerns along this line arose from animal research that suggested there may indeed be a causal relationship between low-calorie sweeteners and fat gain.

For example in one study, scientists gave two groups of rats liquid sweetened with either sugar or saccharin, and unlimited access to rat chow.

By the end of the study, the pups that drank the artificially sweetened water had eaten about four times as much chow as the sugar-fed ones.

Another study found that rats fed saccharin-sweetened yogurt gained more weight and body fat compared to rats fed sugar-sweetened yogurt. A similar study using Ace K-sweetened yogurt produced similar findings.

In each of the cases, the chemical sweeteners appeared to interfere with the rats’ natural mechanisms for regulating caloric intake. Scientists also noted that rats fed the artificial sweeteners experienced a smaller increase in body temperature following their high-calorie meals (indicating a reduction in the thermic effect of food).

There are several factors to consider when evaluating research like this, though, including gender and dietary and genetic elements.

Male rats gained more weight than females, for example, and obesity-prone rats gained weight on the diet of artificially sweetened yogurt while obesity-resistant ones didn’t.

Furthermore, females fed a high-fat, high-sugar diet gained weight after being introduced to artificial sweeteners, but those that previously ate a regular diet of low-fat chow didn’t.

More importantly, though, is looking at what this all means for us humans. After all, we may share ~98% of our DNA with rodents, but we aren’t big rats.

Well, much of the current concern started in 1986, when a large cohort study of 78,694 women found an association between artificial sweetener consumption and weight gain.

That is, it appeared that heavier women tended to eat more artificial sweeteners than lighter ones.

Subsequent research has added weight to these claims, and so they’ve gained entrance to the mainstream health and fitness echo chamber.

Artificial sweeteners are making us fatter, we’re told. End of story.

If we take a closer look at the science, though, it’s not that cut-and-dried.

The first thing we have to realize is the bulk of the research adduced to support this position is observational science that can’t establish a cause-effect relationship.

You’ve probably heard the saying “correlation isn’t causation,” right? Well, that’s what we’re talking about here.

Just because two things appear to be linked (artificial sweetener consumption and body fatness, in this case) doesn’t mean one is causing the other.

Something else could be causing the weight gain (like uh, overeating), and artificial sweeteners might have no bearing on this behavior whatsoever.

In fact, cause and effect might be the other way around, a phenomena known as reverse causation. In this case, the outcome being investigated (weight gain) is causing the predictor (consuming artificial sweeteners).

For example, many overweight people start drinking diet sodas in the belief that it will help them lose weight, but make no other dietary or lifestyle changes. Thus, when they continue to gain weight, artificial sweeteners can become guilty by association.

The type of research that can establish causation, though, is the randomized controlled trial (RCT), which is carefully designed to investigate the effects of a specific intervention.

And when we review the RCTs available on artificial sweetener consumption, the picture becomes clear.

In one such study, participants replaced calorific sweeteners with artificial ones and followed a proper weight loss diet and exercise program. They lost a significant amount of weight–just as much as scientists predicted they would, indicating normal metabolic function.

In another RCT, overweight subjects on a weight loss program were separated into two groups. One drank 12 ounces of water per day and the other drank the same amount of artificially sweetened beverages.

Ironically, the group drinking the sweeteners lost more weight than the water drinkers.

That doesn’t mean that diet soda is better than water for weight loss, of course, but it tells us that so long as you’re in a caloric deficit, it won’t get in the way.

Can Artificial Sweeteners Help You Lose Weight?

sugar substitutes weight loss

Now that you have a deeper understanding of artificial sweeteners, this question may have occurred to you.

And it’s a good one.

Logic would suggest that using artificial sweeteners to reduce consumption of sugar and other calorific sweeteners should help reduce your caloric intake overall, and thus support your weight loss efforts.

Well, there’s research to back up that line of thinking.

Contrary to the research I mentioned earlier, that suggested a connection between weight gain and artificial sweetener use, studies have found that artificial consumption is associated with lower, not higher, body fat levels.

Well, the answer is yes, if used to reduce caloric intake, artificial sweeteners can help you lose weight faster.





























The operative words here are “if used to reduce caloric intake,” though.

As energy restriction drives weight loss, anything you do that further restricts energy intake results in faster weight loss.

Whether switching to artificial sweeteners will help you lose weight faster, though, depends on how you’re dieting.

  • If you’re strictly following a proper meal plan that accounts for everything you eat and drink, then it can.
  • If, however, you’re eating intuitively (no planning or tracking—just going by feelings of hunger and fullness), then going artificial is less likely to help.

This is because while artificially sweetened foods and drinks are sweet and (generally) lower in calories, they don’t result in the same levels of satiety (fullness) and satisfaction as food does.

And the body’s natural response to this partial fulfillment is what you’d expect: get more satisfaction (calories).

This is probably why research shows that many people that consume artificial sweeteners generally compensate for the calories “saved” by eating more on the whole.

Unfortunately, that defeats the whole purpose of swapping the simple sugars for the low-calorie sweeteners. In the context of body weight, calories are calories.

The Bottom Line on Artificial Sweeteners and Weight Loss

sucralose weight loss

By themselves, artificial sweeteners can’t raise or lower your body weight.

Only calories can do that.

When viewed in the context of your diet as a whole, though, they can cut both ways.

Research shows they can passively nudge caloric intake up by stimulating the desire to eat (and especially in people that already eat a lot of sugar), which makes it harder to lose weight.

On the other hand, they can be used to subtract calories from your diet that would otherwise be used on sweet foods and drinks, which makes it easier to lose weight.

Your dietary habits will determine how it goes for you.

If you’re a staunch meal planner, then artificial sweeteners can help you lose weight faster (or at least more enjoyably) because you know exactly how many calories you’re eating every day and why.

If you’re not one for planning and tracking, though, they’re less likely to help because they can cause an uptick in natural appetite, negating any calorie-saving benefits.

What’s your take on artificial sweeteners and weight loss? Have anything else to share? Let me know in the comments below!

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I'm Mike and I'm the creator of Muscle for Life and Legion Athletics, and I believe that EVERYONE can achieve the body of their dreams.

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  • Tyler

    Hi mike
    What about the health side? Isn’t sugar and honey better for you than the articficial sweetners?


    • I’m interested in hearing thoughts on this, too, Mike. Not that sugar is “good” for us, but a moderated dose of fructose is healthier than Nutrasweet, Sweet n’ Low, and all those other lab-designed sweeteners, right? Or is the naysaying all just hoopla?

    • Dan

      Me too, but one thing seems to come out, first, are artificial sweeteners ‘bad’ for you in some way, nutritionally or chemically? Seems like the answer is pretty much, no, given all the animal and human studies. So then not sure how sugar or honey would be ‘better’…unless you needed the carbs. You have posted this before: https://www.muscleforlife.com/sugar-facts/ so neither is ‘bad’ for you.

    • I’d say the health risks are greatly exaggerated, but, that said, there IS evidence that regular consumption of artificial sweeteners (in high-ish doses) may be harmful to our health over time.

      That’s why I personally avoid them for the most part (I have some artificially sweetened gum here and there) and chose to sweeten my supplements naturally.

  • Chris

    Thanks for making this article Mike, it addresses one thing I’ve been thinking about for a long time.

    So many sports supplements are laced with Ace-K it’s always been on my mind.

    I understand how artificial sweeteners may or may not impact weight fluctuations through this article, but~
    Did you happen to come across any research that determines whether certain artificial sweeteners may have other pros/cons?
    For example, Ace-K which is used in a lot of protein powders/pre-workouts, etc is said to be carcinogenic~ and have certain impacts on the brain… etc etc.

    • My pleasure Chris.

      I’d say the health risks are greatly exaggerated, but, that said, there IS evidence that regular consumption of artificial sweeteners (in high-ish doses) can be harmful to our health over time.

      That’s why I personally avoid them for the most part (I have some artificially sweetened gum here and there) and chose to sweeten my supplements naturally.

      • Jill

        My problem with artificial sweeteners is that they perpetuate sugar cravings. When you cut out (or way back on) sugar/artificial sweeteners, the daily (hourly?!!) cravings subside and naturally sweet foods start tasting a whole lot seeeter and more satisfying.

        • Hey Jill, if you’ve found that to be the case for you, then that’s a good reason to cut back. There probably is some merit to the idea that getting used to eating tons of super-sweet foods isn’t an ideal plan.

  • Dan

    Thanks Mike. I’d heard, and my family had kept telling me, that aspartame was the devil for weight loss. My diet coke consumption is something of legend. Anyway, its good to see that my personal experience is born out, so far this year lost 60lbs fat and gained 15 muscle…mostly on BLS dieting (started out on Medifast, which also uses artificial sweeteners.)

    • Hahah, well, I’d say the health risks are greatly exaggerated, but, that said, there IS evidence that regular consumption of artificial sweeteners (in high-ish doses) can be harmful to our health over time.

      That’s why I personally avoid them for the most part (I have some artificially sweetened gum here and there) and chose to sweeten my supplements naturally.

      Wow, amazing job. That rocks. I’d love to put you up on the site at some point if you’re interested.

      • Dan

        I was thinking about it at 1 yr. Love your site, has made a big diff. Trying to figure out how to get my wife to try TLS (delicate subject…)

        • Sounds good! Glad you got a lot out of the content.

          Well, words of encouragement, praise, and admiration always help!

        • Marian Boricean

          I agree with Dan. Getting the wife to start a workout routine/program, is not only delicate. It’s outright dangerous 🙂

    • Nice work on that fat loss and muscle gains, Dan! Excellent. Glad you enjoyed the article.

  • denvercoder10

    Great article Mike! Did you come across any studies on the effects of artificial sweeteners on insulin levels? I have read that it may spike insulin levels even though it has close to zero calories, which would be especially undesirable when doing IF. Thanks!!

  • cloco

    I like this article and, like most of your other ones, it was backed up by science. Maybe you could follow up with one about fats (or maybe you’ve already have). I once compared a pack of Fritos that was fat free to a regular pack. It had more calories than the regular one. I guess because they added sugar and other stuff to compensate for the taste.

  • Casey Collier

    I think this article is dead on. Track your macros and use no calorie sweeteners to replace more desirable sugar filled foods, such as chocolate syrup, BBQ sauce, and even soda. This way you will be getting the benefit of being able to eat more nutritious foods with the remaining calories you saved by going sugar free, thus improving health.

    The amount of artificial sweetener needed to cause any long term damage is not possible for most people to consume. You would have to drink over 20 cans of diet soda, every day for the rest of your life to exceed the acceptable daily intake of aspartame (http://greatist.com/health/are-artificial-sweeteners-really-going-kill-me). Keep in mind this is 100 times less aspartame than the lowest dose that the FDA determines could cause harm. Each sweetener has its own unique ADI, some easier to reach than others. What Mike said is good, moderation is key.

    • Thanks Casey!

      I’ll add that I think we’re going to learn in the next decade or so that artificial sweeteners (some, at least) are more detrimental than many people currently believe. The research being done into how they can affect the microbiome (and how much that, in turn, can affect) is particularly interesting…

  • Marian Boricean

    It’s so awesome when you come up with an article confirming what you already thought to be true. Especially when I put a lot of value in your teachings 🙂

  • john

    you are a joke…..a want to be guru….

  • Timothy Bailey

    This is a very helpful article! Ia question though. Are not done sweeteners unhealthy/cause cancer etc?

    • Thanks Tim.

      No, they definitely don’t cause cancer. I mean, maybe if you were to eat a few hundred servings per day they could, haha.

      I’ll add that I think we’re going to learn in the next decade or so that artificial sweeteners (some, at least) are more detrimental than many people currently believe. The research being done into how they can affect the microbiome (and how much that, in turn, can affect) is particularly interesting…

  • Anastasia Chouryguin

    Thank you Matthews! Do you have an article about info gathered about natural sweeteners?
    Erringly, was thinking of the polyols reading the comments on here!
    Erithritol is being shown to be an insecticide (Dr. Axe), mannitol has a glycemic index of 36 (mark sisson).
    Xylitol (more effective than flouride for remineralization (complexing w Ca) also stimulates collagen production in rodent models!

    • Thanks Anastasia!

      Not yet, but I do plan on writing one! I personally like xylitol and stevia most.

  • Nikki

    Great great article. My question is am I defeating the purpose if I add equal to my fruit infused water?? I just can’t seem to find a simple answer.

    • Thanks! No. Only if the equal makes you crave more sweets and give in. If you stay disciplined, and successfully use it to curb cravings, you’re golden.

  • Great stuff as usual Mike. This has been on my mind. I meal plan and track my calories relentlessly. I do make use of Stevia and I do make small use of some of these drinks that use sugar alcohol, like erythritol. I would love to get an article on those specifically, since they seem to be newer (?) and the Stevia stuff is “natural” (depending on the mix).

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