Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
26 Jan

The Not So Definitive Guide to Diet Soda

Before I begin, I want to make something clear: this is not your standard definitive guide to whatever. I’d like to be able to issue a proclamation regarding diet soda that stands the test of time immemorial, but I cannot. Research is still in its infancy, and exactly what diet soda does to those who drink it – if anything – is incredibly confusing. The one thing I can say with any certainty is that, while it’s unfair to say it will kill you or give your unborn child prenatal tumors or make you impossibly obese, you’re probably better off without diet soda. It tastes weird, the list of unpronounceable ingredients is too long for my comfort level, and I’ve seen one too many unsuccessful dieters that seem to live on the stuff.

There are two things to consider when making any conclusions about diet soda’s place in a healthy diet. Do the ingredients used in diet soda pose a threat to your short-term or long-term (or that of your offspring’s) health? Is it a kind of sugary methadone, impeding healthy eating by making it harder to kick the desire for sweet things in your mouth because, well, you’re constantly putting things in your mouth that mimic sugar? Let’s dig in.

First, the ingredients. What goes into a can of your average diet soda?

Carbonated water, some sort of food coloring, and preservatives like potassium benzoate are all innocuous enough. Nothing to worry about there. You won’t see Mercola issuing dire warnings about Caramel Color No. 76 anytime soon. It’s the other stuff that interests (or worries) us: artificial sweeteners and (to a lesser extent) phosphoric acid. Let’s take a look at the two major sweeteners in popular use, aspartame and sucralose. Are they dangerous?

Aspartame gets a bad rap. High dose rat studies implicate it as a carcinogen, but in exceedingly large amounts. A can of diet soda a day probably won’t give you cancer. Would I avoid it as a pregnant mother? Yes. Would I be wary of drinking several cans a day? Yes. The basic takeaway is that while the clinical evidence of immediate danger upon normal ingestion of aspartame is lacking, inconclusive, or unclear, the vast amount of anecdotal evidence from people linking aspartame to headaches, migraines, panic attacks, and other maladies gives me great pause. I mean, the stuff tastes horrible, and that’s enough for me, but some people appear to have real health issues with aspartame. Not everyone, obviously, but some do. If aspartame appears to give you trouble, don’t let PubMed convince you that it’s harmless. It may very well be safe in the amounts we typically consume in the majority of people, but you can’t ignore your own experiences.

Also known as Splenda, sucralose is a popular sweetener that’s often called “natural” because it’s the product of selective sucrose chlorination. It’s 3.3 times sweeter than aspartame and 600 times sweeter than sucrose. It seems to have less of a disgusting aftertaste than aspartame (it’s all foul to me, though). Like aspartame, most of the studies reporting negative effects used insanely high doses of sucralose. I’m talking doses in the area of thousands of Splenda packets a day for months on end. I’m no fan, but I don’t think normal consumption of the stuff will kill you. There was a study that found normal doses (between 1.1 and 11.1 mg/kg per day; recommended maximum daily dosage is 5 mg/kg) of sucralose negatively impacted the gut flora in rats and lead to weight gain, although a later review called the study’s results into question. I’ll pass, but thanks, expert panel. There’s also the fact that sucralose is usually combined with something called acesulfame-K (potassium), another sweetener that many researchers think needs more toxicity tests. My take? Studies showing negative effects may be overstated or misguided, but why take the risk for that weird chemical aftertaste? Just avoid the stuff to be on the safe side.

And then there’s phosphoric acid. Here’s how the story supposedly goes: phosphoric acid, which soda makers use in place of pricier citric acid, leaches calcium from your bones and reduces bone mineral density. Is it true? Well, it’s become pretty clear that foods containing dietary phosphorus – like meat, dairy, and other “evil” foods – strengthen bones, rather than leach from them. But phosphorus isn’t exactly the same as phosphoric acid, which epidemiological studies have connected with loss of bone mineral density and osteoporosis. One in particular found that only colas (both diet and regular) were strongly associated with loss of bone mineral density. What do colas have that other diet sodas largely do not? Caffeine plus phosphoric acid. A more recent controlled trial found that only fizzy drinks containing caffeine resulted in increased calcium excretion; phosphoric acid content exerted no effect, either alone or in concert with caffeine. I don’t think we can implicate phosphoric acid just yet.

Okay, but remember: we’ve got to be careful when analyzing a food’s worth by singling out one of its constituent parts for good or for bad (although diet soda is by all definitions not food, it is a consumable whose stated purpose is to help dieters lose weight by avoiding sugar). Let’s judge diet soda on that. It may be technically safe to consume, but does it do its “job”? Does it help us lose weight by replacing our sugar intake with non-caloric sweetener intake and reducing cravings?

By most accounts, no. If you look at the literature, diet soda has repeatedly been shown to correlate with weight gain and increased incidence of metabolic syndrome:

One study found evidence of a linear dose-response; the more diet soda people drank, the more likely they were to be overweight or obese. As Sharon Fowler, the author of the study, puts it, “for each diet soft drink our participants drank per day, they were 65 percent more likely to become overweight during the next seven to eight years, and 41 percent more likely to become obese.”

Another study, which I covered a couple years ago, analyzed the diets of more than 9,500 men and women between the ages of 45 and 64 and found that drinking diet soda was associated with a 34% higher risk of developing metabolic syndrome – the perfect storm of high triglycerides, belly fat, insulin resistance, and obesity that’s so popular nowadays. This was an even stronger association than the one between the “high-meat, high-fat” Western diet and metabolic syndrome.

Authors of both studies speculate that diet soda drinking just extends the life of sugar cravings, rather than eliminating it. In this scenario, diet soda doesn’t regulate the desire for sugar; it increases it, and diet soda drinkers are simply replacing those empty calories with real sugar. This makes sense, and I think it’s part of it, but a couple other studies suggest that something else is going on entirely independent of caloric intake:

The dietary habits and weights of a homogenous group of middle aged women were tracked for a year. Regardless of initial weight status and inexplicable by “food consumption patterns,” users of diet soda were more likely than nonusers to gain weight. They didn’t eat markedly different from non-soda drinkers and yet they got fatter. It continues…

A more recent study broke rats up into two groups. The first received ad libitum oral doses of water sweetened with the maximum Acceptable Daily Intake (ADI) of saccharin, aspartame, cyclamate, and acesulfame-K (the same formulae used in commercial sweeteners), while the second group received plain water. Both were given ad libitum access to standard rat chow (which usually resembles the SAD: a disgusting mix of vegetable oils and sucrose). While caloric intake did not change between groups, the rats given non-caloric sweeteners experienced greater increases in bodyweight. The rats apparently weren’t driven to eat more because of confused satiety signals, and yet they still gained more weight. What gives?

Are diet soda drinkers eating more actual sweets to make up for the missing calories? Are their satiety signal hormones being altered by some chemical additive? Or is something in the diet soda actually causing weight gain independent of caloric intake?

We simply don’t know. We do know, however, that our bodies respond to everything they encounter. You lift a weight, you send a message to your body (build more muscle, make bones denser, establish neural pathways for movement!). You put food in your mouth, that elicits a response, even before the food hits your gut, as with the carbohydrate mouth rinse that increases athletic performance. It may be that introducing artificial sweeteners directly to your gut (bypassing the tongue) doesn’t affect subjective satiety or satiety hormones, but that’s not how we drink diet sodas. We taste them. With our tongues. And there is a decent amount of (mixed) evidence that certain artificial sweeteners in certain situations in certain individuals can actually elicit hormonal responses from taste alone, leading to hunger that isn’t really there and perhaps even insulin to handle dietary glucose that was never actually eaten. The details of any effect artificial sweeteners have on our hunger hormones are still being teased out, and the subject demands a dedicated post sometime in the future – so stay tuned for that.

In the end, diet sodas contain potentially harmful chemical additives and phosphoric acid that may or may not leach minerals. The majority of people who drink them to lose weight are unsuccessful, and most epidemiological evidence and some clinical evidence has linked diet soda intake to increased obesity, even irrespective of caloric intake. It may be that tasting sweet stuff without a corresponding caloric dose is throwing off our satiety signals and messing with our normal hormonal response to food, or perhaps relying on fake sugar just makes it harder to give up the real stuff.

Of course, whether they have a place in your diet is up to you. Maybe you’ll buck the trend and lose more weight and experience greater relief from sugar cravings with diet soda. Maybe you have one every few days and no more. If you’re a dedicated diet soda addict, maybe experiment with slowly eliminating it from your diet. Drink a bit less than usual and see how you feel. Try to save your 80/20 allowance for something a bit more fun, like maybe a high quality full-fat ice cream or a hunk of super dark chocolate (which actually has some nutritional merit, like good dairy fat). I’m gonna say that ideally you ditch them altogether, mostly because they seem to reinforce bad habits in most people and because the long term effects aren’t fully known.

Whatever you do, don’t start a diet soda habit after reading this post!

Comments? Concerns? Give me your diet soda stories. I want to hear about the aspartame headaches, the effect Splenda has on your satiety, and anything you can think of. Don’t hold back!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. I never drink diet sodas, they always have a metallic or “chemical” taste that I do not like. The few time I drank a diet soda with Aspartame I got a weird spacey feeling followed by a subtle headache. I’ve always avoided it since.

    I used to drink a sugar-soda (now with HFCS) a few times a week at lunch or dinner. One day, long before I discovered Atkins/LC, I was drinking a Coke and was curious how much sugar was in it — something like 8-10 teaspoons or 20 sugar cubes. I decided that I would never sit down and intentionally EAT 20 sugar cubes with a meal and that so much sugar could not possibly be good for me. I quit drinking carbonated sugar water that day. (It wasn’t till years later, when I discovered LC, that I learned sugar is added to *everything*).

    As far as diet sodas, I think they are generally a bad idea (even apart from any questionable chemical additives). I think diet sodas just nurture and sustain a sweet tooth. I might have read it here, but someone somewhere made a wise comment on a LC/Primal site that they never could commit to the lifestyle until they gave up on trying replicate HC foods, i.e. LC pancakes, LC Pizza, LC Chocolates, etc. They had to learn to eat LC/Primal and if they wanted pancakes, pizza, soda or chocolates they ate the real-deal once in a (presumably great) while.

    dmfdmf wrote on January 27th, 2011
  2. I quit my diet soda/energy drink consumption over this last month and replaced it with real sugar — fruits and dark chocolate and the occasional Korg treat (cake, ice cream). Two big surprises: One, I was able to eat small amounts of “real” sugar and be satisfied; in past efforts at a general low-carb diet full of fake sugars I’d get massive sweet cravings and binge. Two, the weight plateau I’d been stuck on for 6 months broke almost overnight. A big daily Primal Salad at lunch has also played a part in that I think :)

    Jenn wrote on January 27th, 2011
  3. I have a different philosophy.

    If you eat good, clean, wholesome foods, like on a primal diet, the occasional sweet indulgence would not do much harm at all.

    So if you’re gonna splurge, why not just eat or drink some real sugar?

    I’ll have ice cream perhaps 3 times a month – but, of course, I try to only buy brands that have like 3-4 ingredients i.e. cream, milk, sugar, vanilla.

    Or if I want a soft drink as a dessert, I like micro-brewed, craft style cream soda or root beer – you know, the kind made with real sugar, not HFCS.

    If your trying to kick a sugar habit, I could see using diet soda to wean off the sweet tooth…maybe.

    But if you’re not addicted, and wish to have the occasional indulgence, why would you use Diet, artificial sweetener crap?

    Dave from Hawaii wrote on January 27th, 2011
    • I agree man, its the ADDICTION that’s the problem, not the sugar itself.

      Indulging TOO FREQUENTLY will make you addicted, and we see the results everywhere.

      Graham wrote on January 28th, 2011
  4. I have to admit to starting to drink diet soda a few years ago. It actually did help me shed a few pounds though I constantly wander in the back of my mind if it is damaging my body.

    A great alternative I use sometimes is a splash of fruit juice in sparkling water. Delicious and good for you!

    Dustin wrote on January 27th, 2011
  5. I have lost 45 lbs while continuing to drink sodas w splenda. I “limit”myself to 3 a day which is way down from previously. I intend to reduce it more,eliminate it or replace w iced tea.

    uberbulldog wrote on January 28th, 2011
  6. My mother-in-law was drinking a ton of diet sodas in the course of the day. After finding out that they might be setting off her migraines, she quit. Well, she still gets migraines, but her fibromyalgia has pretty much disappeared. She was getting to point where it was painful to walk, so her quality of life has markedly improved.

    republicanmother wrote on January 28th, 2011
  7. After I quit drinking soda, my headaches disappeared. It seems miraculous.

    Joe wrote on January 28th, 2011
  8. I have read that it is not possible to become technically “addicted” to sugar or another other food stuff (though I personally disagree) but instead, it is a “habit” that has become hard to break.

    Whatever it is, habit or addiction, I am having a very very hard time dropping the diet cola.

    I have cut back to 4 per day as opposed to much more. Talk about “jonesin” for a diet coke zero! :-)

    Annie wrote on January 28th, 2011
  9. I have ADD and I noticed a tremendous improvement after I started avoiding Aspertame, almost as big as the improvement I saw from my prescription of Adderall.
    My memory and ability to focus are much better, my mind isn’t always in a fog like as if I have just woken up, and I am not nervous all the time so my anxiousness in social settings has been improved as well. WATCH THE DOCUMENTARY “SWEET MISERY” to see the dangers of aspertame.

    victorkiriakus wrote on January 28th, 2011
  10. Awesome article Mark, this is exactly what I was looking for when I commented a few days ago on my mother’s unwillingness to kick the diet soda habit (will be forwarding to her).

    I just finished up Gary Taubes (how we get fat..) new book last night so the hormonal response aspect of this post really got me thinking.

    Does the hormonal response from simply the taste of non-caloric sweeteners illicit a similar response to real sugars, thus causing the domino effect of partitioning calories to fat storage more readily ? Seems like that may be the case when you look the study referenced regarding the increased obesity in the diet soda rats intaking similar calories to regularly fed rats.

    Looks like I’ll need to do some searching around, nonetheless great post. If anyone has any interesting links on this topic I’d love to read em. Thanks

    Paleo_or_Die wrote on January 28th, 2011
  11. I observed, when I was first diagnosed with type 2 diabetes (with blood sugar levels extremely difficult to reign in)and was testing ny glucose 7-10 times daily, that excessive use of Nutrasweet, while it would not raise my sugar, definitely increased the time it took for my blood sugar to drop to ‘normal’. I do not know if this is a universal response or if it is rare, but I know from experiment it is real and can only be related to nutrasweet. Now that my glucose levels are completely under control I no longer observe this effect, and I have looked for it.

    FuzzyRider wrote on January 28th, 2011
  12. I had a glass of diet soda at christmas. Mind you i hadn’t had any kind of soda in almost three years before that.

    The chemical taste was strange and really foreign to my palate and left a very nasty feeling in my mouth. Like my body didn’t even recognize it as food. Like i had a swig from a shampoo bottle or something.

    I prefer fresh and clean water with a little lemon and a dash of ginger juice in it. No more sodas for me, like ever.

    Bjorn wrote on January 29th, 2011
    • I hate the taste/smell of meat the same way – I would vomit if I had to eat it.

      SkepticScientist wrote on August 23rd, 2011
  13. I’ve never had a problem with treating soda just like I do alcohol. I don’t keep it in my pantry or drink it at work or to quench my thirst, but I will have a glass during a rare dinner out or a can at the occasional social event. In my mind they both fall in the category of recreational drugs- non nutritive, and probably bad for you if consumed regularly, but fun every once and a while. I’ve never been tempted to up my intake of either, although I’d imagine some people would have addiction problems with soda just like some do with alcohol.

    Spyhop wrote on January 29th, 2011
  14. Hello, I came across your site today as I had forgotten a name of a grass-fed butter I was looking for. I loved this post and am going to be linking to it from my blog. I am a strong believer in no sodas and can’t ever express into words why. Also I try to prevent any contention as soda lovers tend to defend their habit pretty strongly. Thanks for this post I love your wording. Hope you don’t mind I link it up.

    Mary Kathryn wrote on January 29th, 2011
  15. I am one of those who hated soda,it’s not because I think that being thin is cool ’cause I’m neither thin nor am I fat. I am just a health buff and I’ve junked soda since I was 13 and now I’m running 30 and haven’t touch a can of soda nor sip on it. I love my healthy lifestyle and I have to say that you have a good eye opener here for everyone who thinks that “sugar” is really sweet.

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    Kathy30 wrote on January 29th, 2011
  16. This is one post I will be getting my husband to read. He loves his diet coke and – strangely! – is a failed dieter. Whatever he loses just comes back again. Perhaps we have the answer to that problem right here.

    Dawn wrote on January 30th, 2011
  17. Bruce,

    I’ve done a very similar post to this one on my blog. I totally agree with you. Research is still inconclusive at best but the ingredients are definitely unhealthy and well the soda companies are just spending billions to market their so-called diet product claiming that its safe for consumption.

    I’m still more of a pure coke fan than a diet fan by a mile. But after doing a bit of reading on diet sodas, I’ll stay away from it for a long time.

    Bryan wrote on January 31st, 2011
  18. I’m surprised no one has mentioned LaCroix drinks yet… carbonated water with very small amount of natural fruit flavoring. No calories, caffine or sugar. Takes great and gives you that nice refreshing bubbly sensation :) I do not allow anything with HFCS or artificial sugar in my pantry. I limit artificial ingredients and added sugar as much as possible. I wish I could be more selective when it comes to making everything myself, using organic fruits and veggies and grassfed beef; but I am on a very limited grocery budget. I cut out what I can. It disgusts me to see what most people I know eat and feed their children.

    Andrea wrote on January 31st, 2011
  19. This is something I wrestle with. I do drink diet soda everyday and have for years. Some days it’s a little, and some days it’s a lot.

    I went almost primal in mid 2010. I say almost b/c I do eat beans often (wife is from South America & eats it a every meal). I lost 52 pounds in 4 months. So diet soda didn’t stop me from losing fat, but I am concerned about the unnaturalness (is that a word?) of it.

    I’m totally on the fence about it…

    Jason wrote on January 31st, 2011
  20. When I was using diet sodas and Splenda in my tea along with a low carb diet, I lost weight, but the recurring bladder infections (puzzled at least two doctors–they had no suggestions)and blood in my urine were not acceptable side effects. Both went away when I stopped using (artificial sweeteners).
    Also, I have twice used Aspartame in an experiment on ants: I mixed a packet of Aspartame into a solution of lots of sugar in water and put it in a margarine container on the kitchen floor by the door the ants were coming in under. Within a day a I had no more ants and also discovered many spider mites dead on the container. This was enough to convince me to stay away from all artificial sweeteners.

    Colleen wrote on February 23rd, 2011
  21. I started drinking diet soda (Tab back then) when I was 11. I quit during two preegnancies and nursing and would then resume. I would sometimes drink as much as 6 cans a day (diet Coke), but I usually try to keep it to 2. I try and substitute bubbly water when I think I am consuming too much soda. I have never seen an impact on my weight either way but I do tend to feel better if I try to drink more water than soda. But I turn 49 this summer, am at a normal weight for my height and am pretty fit.

    Linda wrote on March 22nd, 2011
  22. I live in Arizona and literally drink a gallon of water daily. In the evenings I usually have 1 can of diet soda or the clear flavored waters that have aspartame. I think that is a safe amount and I have no guilt.

    Ryan wrote on May 4th, 2011
  23. Another reason to quit diet soda: no more acid reflux. For some reason I was being an idiot and never made the connection between 3 Diet Dr. Peppers a day and my terrible acid reflux. Then I quit soda when I started going paleo and I feel better than ever.

    Sami wrote on June 5th, 2011
  24. Before going primal, I used to drink a LOT of fruit juice, especially carbonated apple juice. I thought giving up those drinks would be very difficult for me, but I was surprised that it turned out to be easy.

    However, like other readers, I love carbonated water. I highly recommend the “sodastream” device that lets you carbonate your own water. It’s very convenient, inexpensive, and I like that I reuse the same bottles over and over again. (I used to have a recycling bin full of glass bottles every week. Now I only have to put out the recycling bins once every few weeks.)

    Bahv wrote on June 8th, 2011
  25. Another bullshit concept about diet drinks. If you are diabetic, diet drinks and sweetners are the way to go since sugar is bad for you.
    I use aspertane all the time and my blood sugar wouild be sky high with any sugar product and corn sweetners are the worse.

    ww rutland wrote on June 9th, 2011
    • ww ruland,

      Really? Your comment makes it sounds like soda and diet soda are the only choices on the planet as far as beverages go. How about you don’t drink either of them. Sugar is bad and so is artificial sweeteners. Try some water.

      Jen wrote on June 9th, 2011
  26. Hi Mark, et al. I’m a new convert to the Primal lifestyle and have been amazed at how it’s already having so many positive effects!! I saw a posted question about Zevia “diet soda” naturally sweetened with Stevia and I didn’t see anyone answer…? It’s been my go-to since giving up Diet Coke 2 years ago. I have probably 2 per day on avearge. I also love Vitamin water Zero sweetened with Stevia too. Am I giving up one vice for another or are these ones primal enough for modern day?

    Jenee wrote on June 17th, 2011
  27. 8-12 cans every day for 25 years (pepsi max), getting fatter annually and no hope of quitting. I know the drinks make me thirsty – no other obvious adverse reactions but I would love to give up.

    Maximum wrote on July 2nd, 2011

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