June 09, 2014

Does Diet Soda Cause Weight Gain?

photo: loldig
By Crabby McSlacker

One of the most perplexing research findings in recent years, at least to me, is that drinking diet soda leads to weight gain.

Which totally sounds like crazy-talk! Seriously, drinking no-calorie drinks instead of beverages filled with sugar causes you to add pounds, not lose them?

Well, a couple of studies have come out that might be a bit more encouraging to folks who choose diet sodas in an effort to lose weight, especially those who are not obese and are looking to avoid becoming so.

But, does that mean you should run immediately to Costco and buy 437 cases of your favorite sugar-free beverage?

First off, before we get all sciencey, a couple of DISCLAIMERS:

So yeah, I sometimes drink diet soda. Not a lot, maybe 2-3 sodas a month. Plus I have a lot of stevia in my drinks and there's sucralose and erythritol in some of my Quest bars and other fake foods I eat. And I sometimes drink, of all bizarre concoctions, sucralose-spiked Diet Cran-Cherry juice mixed with some carb-killing apple cider vinegar.

And I'd consume even more of all that stuff if I were convinced it was 100% safe to ingest vast quantities over the long haul.

But this post isn't about whether artificial sweeteners are dangerous or not, which is a contentious and confusing issue that I don't think is as straightforward as either the pro-sweetener or anti-sweetener camps make out.  This post is just addressing the curious question of whether drinking diet drinks prevents or encourages weight gain.

However, my own personal desire to drink this stuff means I'm going to be looking a lot harder to find research that says diet soda ain't so bad than someone who cheerfully eschews artificially flavored anything and is perfectly content with their boring old water. I will still drink my boring old water, but I'm NOT content with it.

OK, now that we've got those disclaimers out of the way...

The Link Between Obesity and Diet Sodas

So I've always been pretty unimpressed with research linking diet sodas to obesity, based solely on the fact that obese people drink more diet sodas than slim ones.

That's like noticing old people use canes and walkers way more than young people do, and then concluding that using canes and walkers will make you old.

It makes more sense to me to think that fatter people are going to be more motivated to drink lousier tasting sugar-free drinks to save calories! As opposed to people who can drink the real stuff because they don't need to lose weight in the first place.

I may be missing something, but it seems to me unless you can take a huge bunch of people and randomly make half of them drink diet soda for at least a decade or so, and absolutely prohibit other folks from drinking it and then see what happens to everyone's weight, you're not going to be able to tease out the impact of self-selection on long-term weight gain. Otherwise, the tendency of people gain weight more easily to shift to low calorie drinks is gonna f--ck with your results.

So phooey on those studies. What else we got?

Artificial Sweeteners and Fat Rodents


Well, a number of years ago there were other signs of trouble which I decided to ignore: Rodent studies started showing that the something funny was going on with weight and diet foods.  Like in this  rat study, where rats who ate artificially sweetened yogurt gained more weight than those whose yogurt was sweetened with glucose.

(And btw, who knew rodents ate yogurt in the first place?  I'm imagining Dannon and Yoplait should jump on that real quick with rat-friendly yogurt marketing campaigns! Let's not let any potential yogurt consumers go untargeted, right?)

Potential Dollars Left on the Table, Yogurt People.

Anyway, the researchers theorized that why this happened was:
Sweet foods provide a "salient orosensory stimulus" that strongly predicts someone is about to take in a lot of calories. Ingestive and digestive reflexes gear up for that intake but when false sweetness isn't followed by lots of calories, the system gets confused.
And sheesh, talk about confused! I sure was.

I figured if ingesting artificial sweeteners can defy the laws of physics and create energy and mass out of nothing, maybe we could start converting power plants into sugar free sweetener factories? And fill up our cars with Coke Zero and start powering our homes with little packets of Equal and solve the freakin' world energy crisis and prevent global warming! Because who needs to pollute the earth burning fossil fuels when we can just power everything with magical energy-creating fake sweeteners?

But, turns out that what seems to be happening is that some consumers of diet sodas are over-compensating for their beverage by eating more food.  This, to me, is a less alarming finding that that diet drinks are somehow manufacturing pounds out of thin air.

Which Diet Soda Drinkers Seem to Be Overcompensating By Eating More Junky Crap?

There was an interesting study on diet drink consumption and calorie intake earlier this year in which researchers looked what 24,000 people consumed over 24 hours.   Here's what they found:

  • Healthy-weight adults who drank diet sodas consumed less food and significantly fewer total calories per day than did healthy-weight adults who drank sugared drinks.
  • However, overweight and obese adults who drank diet beverages did not consume fewer calories as those who drank sugary beverages; they made up for the sugary sodas by eating more calories from food. Overweight diet beverage drinkers ate 88 more calories a day; obese adults averaged 194 extra.
  • Specifically, obese diet beverage drinkers ate significantly more snacks; 131 calories per day in salty snacks and 243 in sweet snacks, compared to 107 and 213 for obese adults who drank sugared drinks.

So, if there is some over-compensation going on, at least in this study, it seems to be the heavier folks who are doing it.

New Study: Diet Sodas May Help Dieters Lose More Weight

And some actual good news for diet soda fans:

A recent 12 week diet soda study found that dieters who were allowed to drink diet soda lost quite a bit more weight than those who had to drink just water. The diet soda drinkers lost an average of 13 pounds, 44 percent more than the control group, who lost nine pounds.

While the study was industry-sponsored, it doesn't make it totally bogus, and it was peer-reviewed.

However, the quote from James Hill at the Anschutz center in the  diet soda study press release is pretty hilarious:

"A groundbreaking new study to be published in the June issue of Obesity, the journal of The Obesity Society, confirms definitively that drinking diet beverages helps people lose weight. 
Gosh, let's look at what happened during a 12 week diet... and then let's generalize that to a lifetime of weight management, and say we've definitively confirmed that diet drinks help with weight loss?  Because everyone knows once you've gone on a diet for a few months, problem solved!

(Though to be fair, the press release cites two earlier studies showing a similar advantage to diet beverage drinkers after 6 months. But still, 6 months is hardly "long term" in the weight management game.)

So what do you guys think of all this?  Any other diet beverage drinkers out there willing to step forward or are you all virtuous water drinkers?


  1. ((secrets away her mommy merlot AKA diet coke and tip toes off :-))

  2. I am a water drinker, but not a virtuous one. I drink the stuff because I like it. I don't like fizzy stuff, so I watch this whole debate as an amazed bystander. If we were talking about chocolate, now, I'd have opinions.

    Mary Anne in Kentucky

  3. I used to drink diet soda but stopped because I was worried about what it was doing to my bones and my pancreas in the long term. Now I drink water, and iced tea instead of the diet coke don't miss it at all.

    1. Good point Susan, I need to do more research, but I know there are health risks from sodas beyond just the sweeteners in them. All kinds of additives and even the carbonation itself are problematic. But I'm envious of all you who don't miss sodas! I grew up drinking Coke, and would be back downing six packs in a second if I could!

  4. I used to LOVE diet Coke. Lived on that stuff for years. I was overweight during those years, yes, but I don't think the DC had anything to do with it...more likely, the enchirito and crispy tacos that came with the drink, lol!

    I don't drink it anymore, but that's more because I've developed an aversion to artificial sweeteners.

  5. I don't eat or drink diet anything. Full sugar and full fat for me. I recall reading years ago that one of the artificial sweeteners prevented the brain's "I'm full" switch from tripping so them as drank them continued to eat. That's the study I hang on to even though I can't recall which sweetener was the guilty party.

    1. Leah, I am totally with you on this. All those artificial sweeteners freak me out as much as high fructose corn syrup does! I'd rather eat less of the full-whatever versions, personally. I gave up diet soda about six months ago, though I do have a soda on occasion. I have really grown to love water, and there is nothing like it to quench thirst.

  6. I can't stand the taste of artificial sweeteners. If I'm going to indulge, I go for real sugar. But then not too often. :-)

  7. I am a total fiend for the fizzy drinks, but can't have the real stuff due to health issues (lookin' at YOU, blood sugar). Diet sodas became my friend years ago and they make my day better, so I'm glad to see a peer reviewed study that doesn't sound daffy. I drink my boring old water as well, but a day without fizz is just a bit of a bummer.

    1. Oh good, I'm not the only one?? Thank you Heather!

    2. You and me both. I know my life would be healthier without a diet coke, but I feel like I already do SO MANY THINGS that are beneficial to my health, and DON'T do so many things that are bad for my health. I always joke that it is my one remaining vice.

      I'm almost to the point where I just don't care anymore, but I admit that I consider giving it up every once in awhile.

    3. Crabby, you are not the only one! /highfive

      OtF, I feel the same way. It is my one vice and I refuse to give it up. Honestly, in the research about bone loss and other horror stories that get bandied about, I've never seen anyone mention quantity consumed before that becomes an issue. As long as we're not drinking gallons of the stuff per person per day, I really think we're fine with our fizz.

  8. I'm in agreement with HappinessSavouredHot and Leah J. Utas.
    Crabby, if you wanna do a battle of the sugar vs. artificial, I'm all for it. Let's it do in the style of Michael Jackson's "Bad" video.

    1. I'd be a fool to do battle with a Ninja like you Yum Yucky! Can't we have a whine-and-cheese soiree instead?

  9. "Virtuous" water (and black coffee and plain tea) drinker here, and i know i've seen people "justify" an outrageously caloric dessert because of "saving" 100 or so calories by ordering a diet soda.

    My own experience that may not hold true for anyone else: several years ago on vacation, my Sweetie kept offering to bring me a bowl of ice cream for dessert each evening. He would bring it, and i would enjoy it, but it left me feeling hungrier and wanting more each evening, and i couldn't figure out why. Then, one night, i saw him scooping a serving for me from the artificially sweetened ice cream container, and i understood. The sweet taste was promising my body calories it wasn't getting, triggering hunger and cravings for more. The next night, i had a bit of fruit for dessert, and no cravings or hunger.

    That experience put me firmly in the "make it the real stuff or don't bother" category.

    Everyone is different, so others may not have the same experience.

    1. Sure sounds like you found your "sweet spot" Messymimi!

  10. A couple of years ago I was on a diet root beer kick and really enjoyed them and consumed many cans. But that ended. I seem to have lost the ability to drink an entire can/bottle of any carbonated diet drink now. I get about a third through it and that's all I want. As I mentioned in an earlier comment, my new thing is to put just a tiny bit of that water-flavoring stuff in a bottle of Aquafina so it no longer just tastes like boring water, and that's my (daytime) drink of choice. As for whether diet sodas make you lose weight, I have to agree that they are not going to know unless they corral a bunch of people and lock them up for a decade to control what they drink. Ultimately,it's just a choice everyone has to make.

    1. Sounds like a great compromise between naked boring water and sodas, Peggy! (I actually drink a ton of coffee and tea, and was thrilled when the scientists decided most of the water in those actually "counts.")

  11. I decided to quit Diet Coke (and I was a six-pack a day drinker) cold turkey when I heard one doctor claim that the artificial sweetener contributed to urinary urgency. Since I am now in my 60's and that had become a real issue, I decided to see if quitting would help. After only a few weeks, I concluded that it had help significantly! I had already decided to try to lose weight so the switch to water and no artificial sweeteners had to figure into my eating routine. After going off of DC I started noticing that my favorite vanilla yogurt was too sweet. I switched to plain yogurt with unsweetened berries and was much happier. The upshot is that everyone's tolerance for artificial sweeteners is different. It has worked for me so far.

  12. Diet Canada Dry in my hand right now. I go through times that I drink the stuff every day for a week and then don't touch it for months. I can see diet soda being a trigger for junk food. Soda just comes as a side for most fast food joints so switching to diet is likely to just remind me that chicken fingers would go nice with that.
    I have bigger issues to worry about as far a nutrition that I think I will resolve first. Like this weekend! What is the deal with everybody BBQing delicious smelling meat all day! I had to lay on the lavender scented air freshener like crazy before I went crazy!!

  13. Nice review of the literature, Crabby!

    I drink a little diet soda, but not too much. Only Cream soda (Winn-Dixie). Other than that only water. You already know I do not drink alcohol. The less soda we drink the better really. Weight is all about the math.

  14. I drink either water or coffee 90% of the time. The few times a month (if that) that I would have soda, I'd rather splurge and have the real stuff. I hate the fake taste of diet soda to begin with, so I'm not the best test subject for that sort of thing. LOL

  15. I do like to indulge in a diet pop usually 4 times a week, maybe 5. I felt redeemed when Carla admitted to her Mommy Merlot indulgences, and I'm glad to know you're not strictly a "Virtuous Water Drinker" as well, Crabby :-) I don't feel that it gives me the right to eat any additional calories, it's just a treat after working out, with a fizzy mouth-feel different from the coffee and water I consume otherwise. I think I would drink a lot more iced tea if 1) I remembered to make it beforehand or 2) they offered decaf, unsweetened in the store.

    Of course, there IS always beer...

  16. Death Ride GrandmaJune 9, 2014 at 4:31 PM

    Well, I never learned to like artificial sweeteners, and actually, I managed to stop drinking soda quite a few years ago. Now, when I am feeling wild, I reach for - brace yourself - lemonade. My evil food companion is generally ice cream. Or cookies. But I can't tell you how happy it makes me to read your blog and its logical analysis. I especially like it when we are reminded that a statistical link is not the same as a cause-effect relationship. I actually just read an article in the Atlantic about sugar. It spent a bunch of time on HFC and some more on the journey agave has made from oh-so--much-better to oh-so-evil. And it went on to point out that in Australia, ice has a strong statistical link to shark attacks. I loved that example, 'cause, yeah, they happen at the same time. When it's warmer, people use more ice, and go to the beach more. But cause & effect? Not quite.

    Keep on reminding us to be logical and to question what we see on TV!

  17. I drink water and adult beverages...not much in between, with one exception: Diet Coke is the indulgence I allow myself for sitting through all-day meetings at work. I don't have too many of those (thankfully!) but I admit to a little frisson of happiness at lunchtime when I reach for that silver and red label. I go a little crazy-eyed when I have caffeine, since it's such a rare event, but at least I can stay awake through the afternoon speaker...

    The clincher for me, even though I was off soda for a long time by then anyway, was when my sister was diagnosed with rickets. (Rickets! A disease I associate with the turn of the *last* century! And not with adults!) Her doctor laid much of the blame at the feet of her obscene Diet Coke addiction--we're talking a case a day. She had so little Vitamin D and phosphorus in her blood that she was borderline admissible to the ER. Srsly! She went off the Diet Coke cold-turkey and had to get Vitamin D shots (!) every week (!!) for something like three or four months (!!!). Needless to say, neither of us are drinking much soda these days. Also: She's all better now, thank you.

    My husband's exception is ginger ale when he's feeling sick--or sometimes just for giggles--and I've been known to sneak a sip when we have it in the house. I doubt those exceptions, or the unwritten exception for mixers in our adult beverages, are going to kill us (or give us rickets). Or indeed render us fat. We're doing a fine job of that with pasta and bread and cheese and sugar and such. =)

    1. Wow. A case a day. :) That is some good savings when you come off that! But it isn't like I haven't heard about that for sugar soda drinkers.

  18. Oh, and:

    Nutrition studies based on self-reporting of food intake = NOT RELIABLE DATA. Which means most nutrition studies = NOT RELIABLE. Which is why I take all nutrition science reporting with a hefty bucket of salt. (I blame nutrition studies for my elevated blood pressure.)

    But it's not like locking people in a lab to control their intake and exercise is going to result in much that's real-world useful. So what's a nutrition scientist to do?

  19. I used to drink Diet Coke only - no water, sports drinks.....I finally realized that wasn't a great plan (although Diet Coke typically made up my breakfast and lunch along with a bag of Funyons!). I decided to cut down to 1 soda a day and now I probably don't even have 1 a week (no reason just don't always want one).

  20. I don't like the taste of any diet drinks, I love water and I especially love mineral water. One of my weaknesses is "brown heroin", AKA Coke. I don't drink it too often, but once in awhile, I just have to have one.

  21. Don't like the artificial sweetners so if I do drink soda it is sugar. The thing is, I like it with like Mexican food. The really need to look at what people drink their soda with in the first place for meaningful weight loss information. :)

  22. I used to be a devoted fan of the Splenda Coke of the mid-2000s, and when they took it off the market, I pretty much gave up drinking soda other than a real (sugar-full) Coke on rare occasion. Well. A couple weeks ago I went to a meeting at work and had a Coke Zero, a beverage I'd had before and been completely unimpressed by, and...it tasted good. I've been craving it since. I even bought some for the house. I'm hoping this is just a phase, because I really do believe soda's bad for your bones.

  23. I am usually a water drinker, but occasionally drink diet sodas. The research that you have cited makes me feel a little less guilty for indulging. :-)

  24. I think these researchers are missing the bigger picture with these studies. I think they should be looking at overall diet habits, activity levels, current medications, and stress levels, instead of just one thing. There are too many factors that cause weight gain for researchers to try to tell people *definitively* that such and such causes weight gain. Maybe half of those obese people are on antidepressants (which can cause major weight gain in some people - ask me how I know). Do they screen for that in their studies?

    I used to be a heavy Diet Mt Dew drinker about a decade ago. I lost weight when I gave it up. For me, these drinks caused blood sugar problems, ironically. It depends on how deranged the person's metabolism is, I guess. My metabolism is so deranged, it isn't allowed in public without adult supervision.

    I'm finding that most of these studies are a bunch of crap, really. I say find what works for you and stick with that. Everybody's different.

  25. I have read this a lot, that Sodas cause weight gain. I think it's better to avoid it and just stick to water. A few drinks here and there...yeah! But, nothing like the taste of fresh water! Moreover, taking lots of water can help reduce one's appetite.


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