Diet Soda: Weight Loss Aid?

Was Coca Cola right all along?

It’s long been the claim that diet soda will help people lose weight compared to regular soda. It’s simple: diet soda has no calories, regular soda has a bunch. Less calories equals losing weight- simple equation. The diet and artificial sweetened industry survives on this concept being embraced. Billions of dollars are spent on diet products, both on the products and the advertising of them. It is imperative that people keep thinking that diet foods and drinks help you manage your weight.

The problem arises when there’s not much substantial evidence to support this claim from the diet soda industry (or any other food/drink realm for that matter). Many think that drinking diet soda actually makes things worse. The belief is that although you might drink 150 less calories the artificially sweet chemicals you injest wreak havoc on your body and brain, both from a toxicity and sweetness disregulation standpoint, often driving you to eat or drink more to make up for it. The major critics of things like diet soda even claim cancer and brain deterioration stem from the artificial sweeteners used to make diet foods.

Despite the proclaimed drawbacks of things like Diet Coke, many people either 1) still believe it helps them lose weight or keep weight off, 2) don’t believe diet sodas are bad for them, 3) both or 4) are willing to deal with health hazards in order to get weight loss benefits. There’s also the crowd that simply likes the taste or likes it for other reasons. The end result is that despite the lack of actual evidence of benefit/health, a lot of people drink diet sodas, many simply because of the hope/belief it helps with weight regulation.

Then this study came out…

Clinical Trial Affirms Diet Beverages Play Positive Role in Weight Loss for Dieters

“This study clearly demonstrates diet beverages can in fact help people lose weight, directly countering myths in recent years that suggest the opposite effect – weight gain,” said James O. Hill, Ph.D., executive director of the University of Colorado Anschutz Health and Wellness Center, and a co-author of the study. “In fact, those who drank diet beverages lost more weight and reported feeling significantly less hungry than those who drank water alone. This reinforces if you’re trying to shed pounds, you can enjoy diet beverages.”

Interesting. Sounds sort of convincing. But before we go grab a 12 pack of Diet Coke maybe we should look a little closer just in case there might be a few details not disclosed in the headline or top of the story, which is what most people read and form their conclusion from…

The release goes on to give a few details of the study (12 weeks, ~300 folks, half diet soda, half water only drinkers) and how it proves diet drinks help weight loss (an average loss of 13 lbs vs. 9 lbs), finishing up with:

This latest study adds to the body of research demonstrating that diet beverages do not hinder, but in fact help, with weight loss.


Additional research published in 2009 on weight loss maintenance, drawn from the National Weight Control Registry, found that successful weight loss maintainers drank three times more diet beverages than those who had never lost weight.

Ok- so the basics tells us that if, in fact, we do live in a bubble where you can only change one variable and keep 300 people living in the real world perfectly adhered and constant, then maybe this has some validity. It would need to be repeated and tested other ways but it’s off to a good start, if we live in this strange world bubble world. But since we don’t, I’m curious if there’s any other wrinkles in this seemingly silky smooth story…

Clicking on the button Read Full Release at the end of the report and guess what pops up as the only text left out of the report:

The study was supported by the American Beverage Association (ABA), a Washington, DC-based trade association. It was peer-reviewed and posted on Neither ABA, nor any of its members, was involved in any part of the study, its analysis or the writing of this paper.

Hmmm. Interesting but can’t say I’m surprised.

Let’s find the real study…

The effects of water and non-nutritive sweetened beverages on weight loss during a 12-week weight loss treatment program

Upon closer review a couple things pop out:
1. Fully funded by ABA.
2. Two of the authors got money from Coca Cola separate from the funding of this study. They, along with a couple other coauthors, were responsible for study design, data analysis and interpretation.
3. This was data from 12 weeks of a year long study that is yet to be reported.
4. All participants received a cognitive- behavioral weight loss intervention, including meetings, support and weigh ins and energy expenditure monitors, along with coupons for free drinks/sodas and $75-125 for turning in most of their beverage logs.
5. The “water” group had to stop drinking diet soda and was encouraged to drink water but could drink regular soda and sweetened coffee drinks and no limit was put on diet food sweetened with artificial sweeteners (i.e. diet yogurt, diet ice cream).
6. The NNS (non nutritive sweetened beverage) group continued to drink diet drinks as they had before.
7. Participants self reported what they drank and how much, this alone was how they tracked what people drank. There was no report of what they ate.
8. All people were artificial sweetener consumers before this study.
9. There was a dropout rate of 9% and the study was 80% female, 68% White/Caucasian.

Taking all of this in, it would appear that participants in the water group lost a bit less weight and reported being slightly hungrier.

Is it the diet drinks that caused this? The authors seem to think so and want us to believe that it finally puts those pesky negative rumors about diet drinks to rest.

Not surprisingly, I need a bit more.

The NNS group went on a weight loss program (diet/exercise) and got to keep drinking their diet sodas. The water group went on the same weight loss program but couldn’t drink diet drinks. They could however drink regular sodas and eat diet foods. It would have been nice to see what these people ate and drank to see the real impact of taking diet drinks away from people. How do we know that the reason the water group didn’t lose more weight was because they searched our more calories to make up for the lack of the sweet diet drinks they were used to? This and many other questions come to mind as we look at the results of this study.

This is interesting at best but there needs to be a bit more solid research completed until I buy into the diet soda weight loss story. If it is found that indeed diet sodas are better than water for losing weight then it will need to be shown that the artificial sweeteners are not harmful to us. That seems like a much bigger hill to climb. At any rate, health detriment at the expense of weight loss isn’t a great deal to accept.

Thanks for reading, have a great day!

P.S. Here’s NPR covering the results.


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