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How Diet Soda Could Make Us Gain Weight

People consuming low calorie sweeteners may overcompensate by eating more than they otherwise would.

December 5, 2012 |
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Supplementary Info

Sources Cited


Images thanks to: vikapproved.


Erythritol, the too-good-to-be-true nontoxic, low-calorie, tooth friendly sweetener that may even act as an antioxidant. What’s the catch? Well, there are three ways that all noncaloric sweeteners could theoretically be harmful independent of their specific chemistry. Over the years, “Several large scale prospective cohort studies found positive correlation between artificial sweetener use and weight gain,” meaning the people that drank the most diet soda, for example, gained the most weight. The most common explanation for this counterintuitive finding is what's called reverse causation. People aren’t fat because they drink diet soda, they drink diet soda because they’re fat! But there are at least three other less benign alternative explanations. The first is called “overcompensation for expected caloric reduction.” If you covertly switch someone's soda for diet soda without them knowing it, their caloric intake drops, obviously— they’re not drinking all that sugar anymore. But what if you tell them what you did? People who knowingly are consuming artificial sweeteners may actually end up eating more calories. Why? because they’re like hey, I’m drinking diet soda, so I can have two pieces of cake. In this study they gave people an artificially sweetened cereal for breakfast, but only told half of the group what they did. As you can see when it came to lunchtime, the aspartame-informed group ate significantly more than the aspartame-naive group that didn't know any different. Basically, it’s the diet soda with a fast food meal syndrome.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Ashley Rhinehart, RN.

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Dr. Michael Greger

Doctor's Note

In Friday's video Aspartame-Induced Fibromyalgia and Monday's Diet Soda and Preterm Birth some concerns were raised about the artificial sweetener aspartame, but erythritol was given a pass in Tuesday's video-of-the-day Erythritol May Be a Sweet Antioxidant. I'll go through the other two potential harms arising even from harmless low calorie sweeteners in the next two videos.

For some context, please check out my associated blog post: How to Gain Weight on Diet Soda

If you haven't yet, you can subscribe to my videos for free by clicking here.

  • HemoDynamic, M.D.

    Your introductory image says it all:
    Diet coke with a Greasy fried, ground cow carcass and a plate full of (I’m sure) “healthy” peanut oil deep fried fries.
    That Diet Coke reassures me that I’m doing a good thing by watching my sugar intake so therefore I can up the fat– and fat– and fat intake. Atkins has taught them well!

  • R Ian Flett

    There is another aspect here. I read some years ago that the insulin production system is anticipatory. When sweetness is detected on the tongue the insulin production system cranks up immediately, but when the diet soda hits the digestive system there is no sugar to process, so there is just a surplus of insulin that then affects appetite. False messages simply have bad consequences. I suspect that some other artificial flavourings also give false signals to the digestive system.

    • KD

      I have heard this, too. All I know is that when I have a Diet Coke (which I LOOOOVE), it always makes me absolutely starving in a while – like, gonna-pass-out kind of hungry.

  • Andrea

    I Thank God for you, Dr. Greger, for ALL you do. Hawaii Veg Society had mentioned you’d be back in Honolulu next Spring. I am delighted!! God Bless you!

  • Will Kriski

    I’m not saying diet pop is healthy but having a few diet pops a week while doing a Mcdougall diet is not going to have any weight impact. Even as vegans we need to be consistent with our ability to understand and quote the science.