Diet Soda – Is it Bad For You and Can it Cause Weight Gain?

A picture of Is Diet Soda Bad For YouWe know sugar is bad for us and it is often the first thing we try to restrict when we become health conscious.

Those with a strong sweet tooth often turn to diet soda as a healthy alternative. There’s no sugar in it, and it has no calories.

It is not uncommon to see someone order a BigMac, large fries and a diet soda. If I had banged my head against the wall every time I saw that happening, I’d probably be dead.

They probably believe they are losing weight by replacing sugary soda with a calorie free version.

Well, not exactly.

In this article I will answer the question “is diet soda bad for you” and find out whether it causes weight loss, weight gain, or neither.

What exactly is diet soda?

There are many different types. There is Diet Coke, Coke Light, Pepsi Max, Sprite Zero, and hundreds of other kinds.

Unsurprisingly, as people are getting fatter and fatter, these calorie free beverages have become very popular.

What most of them have in common is carbonated water with some artificial sweeteners, colorants and other additives.

Common sweeteners include Aspartame, Phenylalanine, Sucralose, Cyclamates, Saccharin and Acesulfame Potassium (1).

I am not going to talk about individual sweeteners in this article, but take a look at what happens to people when they drink diet soda.

Is diet soda bad for you?

To give you a short answer, then according to the epidemiological studies, diet soda is bad for you. It may even be worse than regular, sugared soda.

Why? I don’t know.

Maybe the sweetness itself affects the brain in some way, making it want to eat more.

Maybe people tend to consume unhealthy food with their diet sodas, possibly because they think they can compensate for the calories they’re “saving” by not drinking regular soda.

Whatever the actual mechanism, there is a clear association between diet soda consumption and several serious diseases.

Diet Soda, Metabolic Syndrome and type II diabetes

Are you familiar with the metabolic syndrome?

It is a collection of symptoms such as insulin resistance, elevated triglycerides in the blood, reduced HDL cholesterol, raised blood pressure, fat accumulation around the midsection, and some others. Basically what happens to genetically susceptible people when they consume a western diet.

It turns out that diet soda may increase the risk of metabolic syndrome.

In one study, published in 2008, they followed 9514 individuals for 9 years. Those who drank the most diet soda had 34% greater chances of developing the metabolic syndrome. Regular soda had no effect (2).

Another study followed 6814 middle-aged and elderly adults for several years and discovered that daily diet soda consumption increased risk of metabolic syndrome by 36% and type II diabetes by a whopping 67% (3).

Diet Soda and Cardiovascular Disease

A study of 2564 Manhattan residents found that those who drank diet soda every day had a 61% higher risk of stroke and heart attack. Regular soda did not increase the risk (4).

Diet Soda and Preterm delivery

In Denmark, a study of 59 thousand women discovered that 1 serving of diet soda per day increased risk of preterm delivery by 38%, while 4 servings per day increased the risk by 78%. Regular soda did not increase risk of preterm delivery (5).

Diet soda and weight gain

Let’s disregard those diseases for a while and focus specifically on diet soda and weight gain.

The main reason people drink diet soda is that it lacks calories and should therefore help to lose weight. According to the studies, the exact opposite happens.

A study performed at the University of Texas discovered that consumers of diet soft drinks were 65% more likely to become overweight and 41% more likely to become obese, during a seven to eight year period. Regular soft drinks did not have any significant effect (6).

Another study of over 80 thousand women discovered that consuming artificial sweeteners contributes to weight gain (7).


Even though the above studies aren’t randomized clinical trials, the association between diet soda consumption and disease is statistically significant.

I must admit that I was incredibly surprised when doing research on this matter.

I already suspected that diet soda wouldn’t be much better than regular (sugary) soda, but I had no idea that it would actually be worse (according to the epidemiological studies).

Diseases like metabolic syndrome, obesity, type II diabetes and cardiovascular disease kill millions of people each year and anything that may potentially contribute to those diseases should obviously be avoided.

[Update 26/5/2012]: As some readers have correctly pointed out, the studies above only show that there is a correlation between diet soda and disease. These are not controlled trials and do not prove that diet soda caused the diseases. I apologize for any misunderstanding.


  1. I would like to see more detail of the components of diet soda… for instance, is it the artificial sweeter that is solely responsible for it?

    If I get my own carbonated water and make a soda without an artificial sweater, how much better / worse would that be.

  2. Hello Ron,
    honestly I have no idea and this wasn’t answered in the studies, but I will definitely be exploring some of the more common artificial sweeteners in future blog posts.

    Carbonated water is slightly acidic due to the CO2 content. Might be bad for your teeth, but the effects are probably negligible.

  3. Wow, this is shocking.
    But if you drink diet soda and watch you caloric intake, would that be a problem? How bad is aspartame?

    But what do you suggest as “sweet” “healthy” alternatives to diet soda’s?

  4. Hello Jack, if calorie intake is controlled then diet soda will not cause weight gain. But it can be very difficult to control calorie intake completely so I don’t really recommend that approach. Not to mention that diet sodas may be unhealthy regardless of weight gain.

    I will explore Aspartame soon in another blog post, but the research cited above is about diet soda in general, regardless of which sweetener used.

    I really don’t know of any alternatives. Sugared soda, fruit juices, diet sodas: all bad. All I can recommend is water, putting some fresh lemon juice might make it more palatable if needed.

    • I still don’t understand if there is something in the soda that makes you crave more food or because people don’t have to worry about the extra calories from a regular soda they will indulge in extra carolies in their meals or is there something in the soda that makes you hold on to those pounds. I drink about one diet soda a day and drink tea w/ 1 sweet n low and about 6 to 7 bottles of water a day. Will this diet soda keep me from losing weight?

      • Kristjan says:

        It’s possible that the “reward” value of the sweet flavour raises the “body fat set point” in the brain, increasing food intake.

        I’m not quite sure, the studies above show an association, but they don’t reveal what the actual mechanism is.

        There are a lot of people who drink diet soda and still lose weight, so you need to find out what works for you.

        • Lots of acid in diet coke….very hard on teeth, just heard that news from my dentist. I quit. It’s kinda like laying in the sun….never knew it was sooo bad.

    • Creggers says:

      Try Xylitol or Stevia – both are great.

  5. Kris,

    Wow, I knew that all kinds of pop was bad for you, but just not how bad. Secondly, the idea of diet pop, with no calories could cause weight gain never occured to me.

    Thanks for sharing this great info.

  6. I’ve never been a fan of diet soda’s. Regular soda is bad enough but then to create a version that contains even more chemicals is just baffling to me. I am wary of pretty much any low fat or low calorie product. Something just does not sit right with me if they are artificially creating the feel and flavour of fat and sugar. My opinion is avoid these artificial products completely. If you fancy a treat go for the regular soda. Just make sure it is just a treat and not something you drink every day.

  7. Another good post Kris:)

    I remember listening to the Rob Wolf podcast and him talking about how artificial sweeteners could raise insulin, this would be another good reason to stay away from them. Not that there’s anything wrong with normal insulin production (when it’s a part of a healthy and effective diet), but insulin production in the face of no calories sounds like something to avoid.

    So I did a quick search and came up with a good blog post from Mark Sisson ( where he looked at some of the available research and suggested that there is scarce evidence for any of the artificial sweeteners raising insulin. Not that it makes them any healthier, but also not any worse.

    Keep to water, I say! But I also quite like cooled fruit tea as a change, in fact I’ve got one by my side now:)

    Keep up the good work,
    George Super Boot Camps

  8. George, I wish that was all they did, I would much rather drink a diet soda then give myself an insulin shot when my Blood Sugar is too high

  9. I can’t follow your thinking. If diet soda is bad for us because it generates an insulin response when our tongues register the sweetness, then surely regular soda would be equally bad for us for that same reason? And if diet soda makes us “overcompensate” by eating more of other foods, surely that means it’s not the diet soda that’s causing problems, but rather the other foods? What’s the foundation of your claim “diet soda may even be worse than regular soda?”

    The epidemiological studies you’ve quoted don’t seem very informative. It’s pretty obvious that the people who drink the most diet soda are probably the ones who are overweight and looking to lose weight. That doesn’t mean the diet soda causes the weight gain in the first place, or causes the accompanying diabetes/metabolic syndrome. If there was a study that found that giving a group of healthy, lean individuals 2 servings of diet soda day for a year caused them to become overweight and diabetic, then your hypothesis might have some credence.

    The study from the University of Texas can be criticized for similar reasons. It concluded that people who drank 21 servings of diet soda per week had an “almost-doubled” chance at becoming overweight or obese. The people who drink that many diet sodas per week probably drink them because they’re gaining weight; it’s not a cause of their weight gain.

    “The association between diet soda consumption and disease is staggering”. No, I think what’s staggering is a medical student’s inability to separate cause from correlation.

    A personal anecdote: I lost 25 pounds while drinking about 4 liters a week (about 5 cups a day) of diet soda. According to your theory that diet soda inherently is bad, I should have *gained* 25 pounds, if anything. Maybe we can have faith in the laws of thermodynamics after all.

    • i was thinking the same thing as i was reading this..maybe they were more prone to these things to begin with..unless this study was way more’s hard to actually say that these things were more likely to happen bc they drank diet soda…

      on the radio one day, i heard about a survey that supposedly” proved” that giving birth at home was safer than at the hospital..they said bc at home births had less complications..maybe that’s bc the women who gave birth at home were at lower risk to begin with..most women who are at high risk and know that are more likely going to want to be at a hospital

      i’ve come to learn that stats can prove whatever you want them to, depending on what information you include and what you don’t-there are so many variables..different types of sweeteners..caffeine or not, starting point weight/health/age, what the people who aren’t drinking soda are drinking.

      i rarely drink any kind of soda at all. i pretty much drink water or skim milk..and the occasional milkshake..but i’m overweight and diabetic

      • The studies corrected for confounding factors, which gives them a lot more credibility.

        If we were to eat only what has been proven to be healthy in randomized clinical trials, we’d die.


  10. Jack,
    I never said that the effect was because of insulin, I said that it might be part of the reason. I honestly don’t know why the results are the way they are, what you said might explain part of it.

    In some of these studies, people are being followed for a long time, their weight and soda consumption is measured as baseline and then again after a few years. As those years have passed, the diet soda drinkers gained a lot more weight and had increased chances of metabolic syndrome, diabetes, heart disease .. that kill millions of people per year.

    You’re right, until we have a have a controlled trial we can’t prove anything, but while we wait for that to happen we should err on the side of caution.

    I posted all the association studies I found on this matter and they all cause these staggering, highly significant results. I think a fair warning is in order until proven otherwise.

    I also happen to know people who have lost a lot of weight drinking diet soda. If calories are strictly controlled it will not cause weight gain like I mentioned in another comment. The laws of thermodynamics hold, although the human body is enormously more complex than can be explained by simple statements like “calories in, calories out”.

  11. I have been pondering the whole ‘calories in, calories out’ thing for a while and whilst I was reading the last comment by Kris I was reminded of an analogy that may prove useful;

    I am a Metabolic Typing Advisor with and I remember a discussion some time ago about acid/alkali balance and how one the the prevailing myths of good health is the desire to ‘alkalinise’. William Wolcott (the Healthexcel owner) made the point that to talk about a systemic alkalinising didn’t make much sense when each system and level of operation has its own level of acidity/alkalinity. I’ll see if I can find the post where he made this point if anyone is interested.

    My point is that I am not sure where we should be assessing energy balance, because we know that not all the energy we eat passes through the gut wall, so how would we measure that loss and assess the digestive efficiency?

    To chunk up a level of abstraction would take us to asking what the goal of such a saying as ‘calories in vs calories out’ is either to help people figure out how to control their diet or provide a basis for a ‘law of diet’ or some such (and probably others I’m not aware of right now).

    So our goal as educators (well, those of us who are educators anyway) is the find the teaching mode, metaphor or set of lessons that helps our clients reach their goals; if one system doesn’t work, try another.

    My 2c anyhoo.

    Keep up the good work Kris,

  12. Please excuse sentence structure for that last comment, it was typed on my iPhone.

  13. So are the diseases they found diet soda drinkers more succeptible to because of their weight gain? Or solely because they were drinking diet soda? I drink diet soda fairly often, but im still losing weight and I’ve went from 232 to to 190 since I’ve moved.

  14. Bob,
    these diseases are definitely correlated with weight gain, but I don’t really have an answer to your question and it wasn’t answered in the studies.

    I say if you’re losing weight, feeling good and the doctor is happy, then keep at it :)

  15. I drink diet coke because my medication doesn’t allow me to have an alcoholic drink when I go out, but I’ve just been told that Aspartame in diet coke causes Vertigo and yes I do suffer from that, but only since

  16. i’ve drank diet coke

  17. Kris it seems you keep having to say I don’t know or I don’t have an answer. Before giving out advice that could be detrimental such as suggesting the high fructose soda is better for a person you need to be sure not guessing. Why not do your own trial and publish it instead of making a post that you cannot scientifically prove like jack suggested. There is a correlation between increased murder and and increased ice cream sales the factor being warmer weather. Indirect and direct correlations are not the same.

    • Like I said above, until better studies are done I believe a fair warning is in order. I’m not suggesting that people drink sugary soda, a better idea would be to just skip soda completely and stick to water.

      Oh yeah, and some of those studies were prospective studies that adjusted for confounding factors, which gives those results quite a bit of credibility. Interestingly, I’m writing this in the middle of an epidemiology lecture.

  18. I’m curious if you have read any studies on Splenda or Stevia. Are these sweeteners included in the research you have done? Do these sweeteners contain the same ingredients as in diet sodas? From what I have heard, these are more natural artificial sweeteners. I guess ‘natural’ and ‘artificial’ don’t fit very well together. :) If the ingredients are different then I am curious if these sweeteners have the same results. Maybe more research here would draw a better conclusion about what causes such a high percent rise for the problems you listed above.

  19. I wouldn’t trust it unless the statement comes from credible website such as mayoclinic.
    Diet soda: Is it bad for you?
    I drink diet soda every day. Could this be harmful?
    from Katherine Zeratsky, R.D., L.D.
    Drinking a reasonable amount of diet soda a day, such as a can or two, isn’t likely to hurt you. The artificial sweeteners and other chemicals currently used in diet soda are safe for most people, and there’s no credible evidence that these ingredients cause cancer. Some types of diet soda are even fortified with vitamins and minerals. But diet soda isn’t a health drink or a silver bullet for weight loss. Although switching from regular soda to diet soda may save you calories, some studies suggest that drinking more than one soda a day — regular or diet — increases your risk of obesity and related health problems such as type 2 diabetes.

    Healthier choices abound. Start your day with a small glass of 100 percent fruit juice. Drink skim milk with meals. Sip water throughout the day. For variety, try sparkling water or add a squirt of lemon or cranberry juice to your water. Save diet soda for an occasional treat.

  20. In my opinion, Mayo clinic is not a credible website when it comes to nutrition advice, and I have provided plenty of evidence for that in other posts on this website.

    They follow the USDA recommendations, which have received an enormous amount of criticism for being based on faulty evidence:

    Fruit juice is not a good option, too much sugar. No reason to drink skim milk, full fat dairy is healthier:

    Water is the best option here.

  21. I used to work fast food many years ago and I too would cringe every time someone ordered a diet soda with a large, fatty meal.. Until I started doing it myself.

    I spent most of my childhood and teens drinking several mountain dews a day but once i hit my mid 20’s I started feeling like I was getting something like cold sweats and a filmy feeling in my throat so i switched. Been mostly drinking diet pepsi since. Either because of that or just because I’m at the age where people start gaining weight, was when i noticed i was not as thin as i used to be. My diet has barely changed other than diet soda.

    I have spent my whole life drinking soda so I find it extremely difficult to cut it completely out so i found a brand that is low sugar and is practically apple soda with no additional sugar/sweetners. Do you think something like this would be any better?

    • Kara Kleymann says:

      I had a roommate who used to drink diet soda. He didn’t own a car and he walked everywhere but he had a big belly. For some reason he decided to stop drinking diet soda for a while and within a month his belly was half the size it was before! Another month later it was almost gone but then he decided he would drink diet soda again….. a month later the belly returned. I cannot give you an explanation why but diet soda was the culprit… he didn’t change any other habits except for this. Try switching to juice mixed with water/sparkling water and see if it makes a difference for you.

  22. Gudmundur Björnsson says:

    Kristjan !

    There is no significant scientific evidence that proofs that diet soda is not good for you. Discussing this from the viewpoint that “this is your feeling” and saying that the Mayo website “is not a credible source” gives in my opinion your website low credibility, and will not favor serious truth seekers. I suggest you admit this to your readers.

    Gudmundur Björnsson MD MBA CIME

  23. Gudmundur Björnsson says:

    Hi Kristjan and thank you for your reply and recommended literature.
    Your Question was “Diet Soda – Is it Bad For You and Can it Cause Weight Gain?”
    None of your recommended readings answers this question without questionable doubt. The study
    “Diet Soda Intake and Risk of Incident Metabolic Syndrome and Type 2 Diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA) ” has a major design flaw. A correlation is of course between the people drinking diet soda and high blood glucose and obesity. These are the people who are trying their best with the best advertised method drinking, diet soda, but probably not doing anything else.
    Opinions other than yours are not negative, they are a “different” opinion. Let your readers decide if comments are “rude” that is not the explicit function of the editor.
    If you are still going to use “evidence based” in your logo you should have a more neutral view to comments.
    I was in your shoes 25 years ago and I have since learned that if you want to preach serious evidence based medicine you have to be critical in your scrutiny of research and modest and eaven humble in your presentation.
    Otherwise fine- keep on this work.

    • You will not find many things in nutrition that are answered “without questionable doubt”, but I do my best to include references to back up my claims. Almost no other health and nutrition bloggers do this, despite having credentials behind their names.

      When you see several studies indicating a link between diet soda and serious diseases, and no studies showing that there is no link (I listed all the studies I could find), then a fair warning is in order until the controlled trials have been performed.

      But thanks for your comment, I’m sure it will be helpful for my readers in making an informed decision on this matter.

  24. Gudmundur Björnsson says:

    I will follow you on a narrow path, I have a road map if you want :=))

  25. Hello, all I can say is I just stopped diet coke cold turkey about ten days ago. I had the headache for three days straight coming off the caffiene I guess. I have lost six pounds. One thing I have noticed is that I don’t crave all the junk food since stopping the diet coke. Whether or not it is related I don’t know. I just know I talked to a nutritionist about not being able to lose even though I was cutting back on calories and working out. She flat out told me that if I didn’t stop the diet sodas I may never attain the results I was hoping to achieve. the more I read about them the more it makes me realize that I was doing my body a lot of harm by consuming them. Water with some lemon slices are good, plus it’s a natural diuretic. Once I overcame the headaches I was fine with giving them up. I truly hope I am over that addiction. The weight lodd has made a believer out of me. I had to come to terms with, if that was what was keeping me from attaining my goals, I can give it up.

  26. Raymond says:

    I think water is the best choice. Just imagine it tastes like Coke.

  27. I find this very alarming as my daughter who has been an insulin dependant diabetic for 16 years, has alway been told by dietitians to drink diet coke, water etc as these drinks and ok. She was a very healthy slim girl when diagnosed at the age of 5 but as struggled with her weight since the age of 12 when she started to drink diet coke like it was going out of fashion. She now drinks about 3 litres a day and believes this is okay….
    I will be showing her this as soon as I can thank you.

    • Paula, if your daughter is drinking 3 liters/day of diet soda its no wonder she is overweight. If you look at what she’s eating as well you’ll probably find a reason why she’s no longer slim. Take control of her overall diet before it goes too far. Remember that once you are overweight it is near impossible to stay slim. Hence it’s best to ensure your children don’t get overweight in the first place. First thing is to show by example and introduce overall healthy family meals and exercise.

      • My daughters diet is healthy as a diabetic it has to be and she exercises 1-2 hours a day i was just commenting on how shocking the information on diet soda is. And the fact that when she was a teenager the dietitians who should know better told her she was ok to drink it. We do lead by example as we go hiking, walking and to the gym as a family. Myself and my daughters have also been going to belly dancing and zumba classes for a few years.
        Since she read this she has cut out the diet soda and is feeling a lot better and is loosing the weight so once again thank you so much for this information it has really helped my daugher.

  28. Hi sister! i am 12. after reading this wonderful, informative article, i guess it is better to drink water. could we drink juices? like apple or orange (homemade)

    • Kristjan says:

      Water is best. Fruit juices do have a lot of sugar so it’s a good idea to avoid them.

      • You are right that fruit juice contains a lot of sugar. A typical Florida orange juice like Tropicana or Floridas natural contains about 12 percent sugar, while all cokes contain around 10.5 percent sugar.
        For the nutritional value or calorie value it makes no difference that the sugar in the orange juice is natural fruit sugar and not “added”.
        All common fruits contain natural sugar which is a blend of sucrose and fructose.

        White sugar from either sugar cane or sugar beets is also a blend of the two with more sucrose than fructose. What enters the cells in our body is all fructose in the end as every form of carbs has to be translated into fructose before we can digest it. This goes for sugar or sucroae as well as starch in the form of wheat, rice, potatoes or anything else.
        All of these release 4 kcal per gram of dry carbohydrate. Remember that potatoes and wet grains are as a rule of thumb 80 percent water.

        • Kristjan says:

          Hi, thanks for the comment.

          Starch is actually broken down into glucose before it is absorbed, not fructose.

          • Yes, starch breaks into the disacharide sucrose via more complex polysacharides which then break down further into the monosacharide fructose. Then and only then can it be digested.

          • No, starch is a polymer of glucose. It gets broken down into glucose molecules. Glucose and fructose are not the same.

          • ProudDaddy says:

            Kristjan is correct, iceman. Starch is by definition glucose. Check Wikipedia.

          • Kristján, honestly you bullshit. No glucose and sucrose are not the same, but I never said they were.

          • No Prouddaddy. Glucose is sugar. Starch is not sugar. but it breaks down into sugars in our body when we take it up. I do know what I talk about, without wikipedia. I am a food engineer.

          • Kristjan says:

            “What enters the cells in our body is all fructose in the end as every form of carbs has to be translated into fructose before we can digest it.”

            This is false. You’re confusing fructose and glucose here.

            Starch is broken down into glucose molecules, NOT fructose molecules, before it is absorbed. Please do some reading before you reply again.


            “Starch or amylum is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds.”

          • Sorry Kristjan,

            I kept reading glucose in your answers as sucrose. So yes, I was mixing up the breaking down of poly sugars in to di sugars an on into mono sugars with the breaking of starch, which as you say is a poly glucose into the mono sugar clucose.

            With this mixup I hugely watered out the otherwise good message in my initial post.

          • No problem, this happens to the best of us :)

  29. and also, talking about loosing weight, what about exercise? how long, as i am 12, i come back from school at 4pm. (UPSR this year) how am i to exercise? i spend 30 min dancing each day. is that enough? i also play hocky every Monday in school. Thanks.

    • Kristjan says:

      Dancing 30 minutes a day and hockey once per week is plenty in my opinion, but it depends on the intensity. It’s a good idea to also do some intense exercise every week, such as running or something.

  30. I have lost 15 lbs since I stopped drinking soda altogether about 2 months ago, and only drink water, and unflavored natural beverages, mainly black coffee. I still eat plenty of unhealthy food.

  31. Sophie Park says:

    I drink two cans of diet pop every day. Just no, I opened a can of diet coke and took a sip of it and out of curiosity, I researched this topic and once I found out you gain more weight I freaked out and dumped my pop into the sink and served myself a glass of water instead lol! I’m never going back to soft drinks!!!!!

  32. Kris,
    I am sorry to see such negative criticism by a few as clearly you are sharing information from research articles. Being that they are not controlled studies allows readers to use their own discretion but discussion and passing the info could help many. I have also heard some of these studies, but purposelessly paid little attention. I actually have a masters degree in health and physical activity, was certified in nutrition and am an exercise physiologist. I am healthy in every other way except my consumption – or shall I say obsession/addiction to Diet Pepsi. I won ‘t even share how much I drink in a day, and your article has me convinced to stop tomorrow. ( well,I might need my morning jolt at first until I adapt). I thank you and I think you did a great job handling the few negative comments). I will tell you in a few weeks if it helped me drop a few pounds or feel better. Caffeine withdrawal will be tough,

  33. crystalicia says:

    as a small child we grew up not drinking soda it was for adults only in our home my mom would say that the soda would rott the teeth of children. then as a teenager my friends would drink regular soda so one day i tryed it and it was the best ever it came in a glass bottle and it was not diet it was so good i started drinking them every day then twice a day they came in a box and 8 glass bottles.then came the stomach pains and the swelling of the stomach turned out i was addicted to it and had to have it with food or i wasnt eating …… until it ate up the lining of my stomach and caused bad skin problems and lots of other health issues. the soda was so strong before they started putting it in plastic bottles they had to change the formula because the old formula would eat through the plastic bottles before the shelf life was up. so what do you think it was doing to my body and as far as my face when i gave up soda pop my 6 year acne all went away now with most recovering addicts some time” i test the waters “(an old school saying for back sliders)but with diet pop and its only good in low moderations because regular soda makes me dizzy (controled diabetic) because of my poor choices im now obese and it seems like i gain weight just by smelling the food i came accross you web site by searching and studing on how to loss weight fast but safe ….. ps i wanna change so i can LIVE. i need and want to lose 150 in 24 months max without the sugery

    • If you are diabetic then you really, really should consider a low-carbohydrate diet.

      I recommend you check out this website here:

      This guy is not a doctor, not a nutritionist, simply an American man who has completely recovered from diabetes by eating and exercising correctly. He is now at a healthy weight, med free, with fasting glucose in the 75-85 range.

      I highly recommend you check out his site. The dietary advice given to diabetics by dietitians is beyond horror.

      You can also read about him and some of the science behind low-carb and diabetes here:

  34. ProudDaddy says:

    SuppVersity ( just posted a study which might explain an effect on weight loss. It’s hard to believe there aren’t any good RCTs on this stuff. It is also hard to believe so many bloggers get the insulin spike thing wrong.

    • Yeah I’ve done more research on this since I wrote this article. Artificial sweeteners don’t raise insulin, there is some other mechanism at play.

      Btw that is a very nice you pointed out, I have added it to my rss reader.

  35. Thanks, this looks like a very enlightening study. I’m going to read it thoroughly when I get the chance.

    I have access to the full version of the manuscript. I can send it to you if you want, hope I’m not breaking any laws.

    • ProudDaddy says:

      Thanks for the offer. I know other bloggers often share non-open access material, but I’m guessing it is probably breaking copyright law. I’d really like a copy of the full study, but not enough to pay for it. Don’t do anything that makes you feel uncomfortable. Prof Dr Andro says that the authors don’t add much information regarding what might be going on anyway.

      • Kristjan says:

        I just sent you the study, that is if you were using your correct e-mail to post the comment.

        • ProudDaddy says:

          Many thanks. I’ve got some family obligations rest of today (CDT), but I’ll get back if/when I learn anything I think is really interesting.

          Again, Thanks!

  36. ProudDaddy says:

    I commented as follows at SuppVersity:

    Before commenting further on the study, allow me to direct your attention to the following:

    This study indicated that GLP-1 levels in humans INCREASED upon glucose feeding when diet soda was ingested 10 minutes before. (Note to Evelyn: sucralose and acesulfame-K).

    One could easily say that the difference was rodent vs. human, but this might be erroneous. For now, I would assume that the discrepancy is the difference between chronic and acute, and short-term vs all-day, sweetener ingestion. The control was also different: carbonated water vs. glucose-sweetened food.

    That said, the Swithers study discussion does offer a plausible explanation. I call it the “fool me once…” scenario. Other than the fact that the authors use the term cephalic response, which I understand refers to PRE-prandial effects, the idea is that the body learns that the sweetness sensation has become less valid in determining the caloric content of a glucose meal. There is apparently some independent evidence that GLP-1 production is influenced by sweet taste receptors, at least those present in the gut.

    Given the effects of exanatide, it is probably safe to say that the decreased GLP-1 was responsible for the poorer glucose clearance.

    The study should be fairly easy to replicate in humans via a short crossover experiment. If I were the artificial sweetener industry, I wouldn’t sponsor it!

    I’m still making notes and thinking things through, so I may clutter up your blog further in the future. And anyone, please feel free to point out my errors.

    I have always assumed that since lo-cal sweeteners had no insulin effect, they were relatively benign, and we use them quite a bit in our house. I have never changed my behavior as a result of a single study, but Smithers will change that at least to the extent of temporarily eliminating such sweetners and assessing serum glucose and appetite changes. It should also be noted that Smithers was really 6 consistent experiments. (The only anomaly was weight gain in one group which was probably due to them being younger and more rapidly growing).

    Thanks Again, Kristjan!

  37. Gudmundur Björnsson says:

    Wise comment Kris :=))

  38. Bruce Brenner says:

    You are wrong. Diet soda has no calories. Therefore will not cause weight gain. I lost 50 pounds on a great diet and drank tons of diet soda the whole time.

    • Richard says:

      As he said over and over some people do lose weight. Also, some people do have the associated health issues that at least seem to be related to the diet sodas. I too lost 50 pounds on a low carb diet and drank diet sodas, but have since all but given them up because after looking at the evidence believe they are of no benefit at best, and harmful at worst.

  39. I really doubt diet soda causes more weight gain then regular soda, that’s ridiculous. Until they prove and point to what causes diet soda to cause weight gain I don’t believe it. I’ve been drinking 2-3 diet soda’s a day for the last 6 months and I’ve been eating healthy and exercising and I’ve lost 45 pounds. Whatever *weight gain* diet soda causes, it’s extremely small and insignificant. I don’t care what those *studies* show. I’ve even been on phases where I drink entire 2L diet sodas in 1 day and it doesn’t cause weight gain, and I’ve noticed no difference in weight loss when increasing and decreasing my amounts of diet soda. To tell people they’re better off drinking 600 calories of regular soda daily INSTEAD of drinking 0 calories of diet soda when trying to lose weight based on one *study* is not only ridiculous but irresponsible. In fact, my aunt cut out regular soda and replaced it with diet soda, she’s a HUGE soda drinker, many per day. She found herself losing about 1-2 pounds a week making NO other changes. I really think that if diet soda was causing people to gain weight, especially MORE SO than regular soda, as you claim, people would have noticed by now and WAY more research would be going into determining the cause. The FACT is that many people every day switch to diet soda, without changing eating habits, and they lose weight.

    • Kristjan says:

      Did you even look at the studies? These are 7 epidemiological that show a pretty strong association for diet soda, fat gain and disease.

      Until the controlled trials have been performed, I think a fair warning is in order. Your n=1 experiences, although applicable to yourself, do not change that in my opinion.

      There is a possible causal mechanism, you should read up on “food reward” and the “body fat set point” in the hypothalamus. It is pretty complex stuff that I’m going to explain in a blog post one day. Obesity researchers are all over this stuff these days.

  40. Arni Vidar Bjorgvinsson says:

    Well, I’d definitely take that with a grain of salt.. or a pinch of sugar perhaps ;)

    Since it’s start of production in 1985, and indeed since it’s inception in 1965, people have been constantly trying to get NutraSweet (the most common brand of artificial sweetener in the world, and more or less pure Aspartame) off the market by claiming it’s bad for you. In nigh on 50 years, not ONE piece of independent research has been able to prove a single negative thing about Aspartame and the human body.

    And we aren’t even talking about 10 bathtubs a day math here, as we saw with the blue food coloring epidemic a couple of decades ago that caused it to be outlawed in food. (If you ate something like 10 bathtubs of blue M&M’s a day for 10 years you were a somewhat hefty percentage more likely to get cancer… I forget the exact numbers)

    Not even drinking 10 bathtubs a day of Diet soda has been proven to have negative effects, and Aspartame has thus not been outlawed.

    Yes, we do not know the full effects of Aspartame on the body over the course of, say, several generations, but almost a full life age of humans has passed without a single person being unequivocally proven damaged by Aspartame.

    Fear mongering is never good, not in any context. Although we should all strive to eat healthier at all times (probably one of the noblest goals of our century), perhaps people should take closer look at the processed sludge of filth that accompanies the Diet soda intake before putting the blame on something that’s been proven again and again not to be unsafe for consumption?

    • Did you even look at the studies I cited in the article? Sure doesn’t seem like it.

      There are several epidemiological studies that show a strong association between diet soda and serious diseases. I did not cherry pick, I included all the studies I could find.

      If you know of evidence that long-term consumption of artificially sweetened soft drinks doesn’t lead to weight gain in an ad libidum setting, in humans (representative of the real world), then by all means share it.

      Btw my article didn’t discuss aspartame specifically. It is about all artificially sweetened sodas, and there are many other sweeteners out there than aspartame.

      I agree, there is no conclusive evidence linking aspartame specifically to disease. However, there is evidence for artificially sweetened drinks (including those sweetened with aspartame) leading to disease.

      So far, these are only epidemiological studies, but until we have controlled trials then I’m going to take the safety first approach and warn my readers about something that may potentially cause harm.

  41. Arni Vidar Bjorgvinsson says:

    You specifically state that diet drinks are worse than sugared drinks, and you claim that there is evidence to support that claim. And yet all the major drug and food monitoring associations in the world refute these claims (like Halldórsson’s Danish Pregnancy trials) as a matter of course.
    If you look at just a few of them, perhaps even just the biggest like the FDA, you will see that their conclusions are that it’s all a load of hogwash.

    Here are but a few URL’s regarding this issue. The .GOV/.GC ones, however, are the most interesting IMO:

    My objections are also towards claims that other artificial sweeteners (like Sucralose for instance) are harmful, since claims against many of them have been refuted just as plainly as have the claims against Aspartame.

    Now, as for the Diet drinks cause weight gain arguments, no proper studies have been done in this area, and nobody has been able to single out the Diet drinks as the cause of the weight gain. Diet drinks are usually used by people trying to lose weight, and one of the most common mistakes is people going for diet, then doubling their sugar intake because the body is calling for the sugar it used to get from regular soda.. either maintaining their weight, or even gaining some. This, then, is not caused by the Diet drinks, but by the people not properly managing their food/sugar intake.

    Yes, it is good to think about what we’re eating/drinking and yes artificial chemicals are generally worse to digest/handle/metabolize than the real things, but the Diet drinks are by no means the big issue in today’s health crisis. Feel free to warn anyone that will listen about the ‘hazzards’ of artificial sweeteners, but I hope you will allow me to feel free to rebuke it to anyone that would listen to that. :)

    • The thing is, artificial sweeteners have NOT been proven safe in humans.

      I am very well aware of that government regulators deem them to be safe. I am not a government regulator, and my articles are based on my personal evaluation of the current research available.

      Perhaps the regulators haven’t been able to link them to disease, but the epidemiology shows that they are associated with weight gain.

      Here are some studies on artificial sweeteners and food intake:

      Artificial sweeteners and weight gain:

      Until the controlled trials have been performed in humans, clearly displaying their safety, then they have NOT been proven safe.

      Now I’m not going to be “that guy” who completely denies everything that doesn’t support his view. Perhaps the words I used in the article were a bit too blatant, but I still stick by what I said.

      I really think probably the only effect of these drinks is to increase food intake and lead to weight gain. But weight gain leads to all sorts of disease, including those I mentioned in the article, so they are most likely secondary consequences of the weight gain.

      I do agree that there is no conclusive evidence to prove that artificial sweeteners/diet sodas either do or do not cause harm. The evidence I looked at, given what I have read about the food reward theory of obesity, seems to point to the fact that they are in fact harmful.

      I did NOT cherry pick studies, I included everything I could find on diet drinks and health. Until this has been proven wrong, then I will leave this article unchanged. When diet sodas have been proven safe, then I will update it.

      Here is a study that evaluates artificial sweeteners and weight gain, while specifically looking at it from the standpoint of the food reward theory of obesity:

      Really, it is hard to imagine how something that doesn’t contain calories and doesn’t raise insulin could lead to weight gain. It didn’t make sense to me until I read up on the food reward theory, and its effects on the body fat set point in the hypothalamus.

      Here are some articles on the body fat setpoint and the food reward theory of obesity, written by a respected PhD obesity researcher:

      I would appreciate it if you would read these articles (at least the three last ones) and tell me what you think.

      • Good reply Kris. One thing I particularly like about your replies is that they remain balanced and non-aggressive.

        As regards the ‘no calorie, no effect through insulin’ issue with respect to weight gain, we should remind ourselves that one of the things that promotes weight gain also has nothing to do with calories; sleep duration.

        I did a transcript of a podcast about this very issue on my blog, you can find it here (please feel free to edit this link out if you want) :

        Happy reading folks,
        I’m off for a drink of water!

      • Arni Vidar Bjorgvinsson says:

        Apologies for the late reply, but I have been too busy to read your post/links and formulate a response.

        I have never claimed that is has ever been proven that diet drinks are safe for consumption. The problem is that is has never been proven that they are unsafe either. The studies that have tried to do this, for the past 20 years or so, have all failed to prove anything at all, and have thus been rebuked.

        We may well find out in another 20-50 years that there is evidence that they ARE bad for you, but until then your post (and others like it) are merely spreading unsubstantiated rumors and fear mongering where there are no actual hard evidence to support the claims.

        Just like you wouldn’t particularly like it if I accused you of a crime without having any evidence to prove it, so should you (and that’s ‘you’ as in plural, as in all anti-diet soda evangelists.. not ‘you’ as in singular) not be passing judgement and making claims that you can not prove without a doubt. You can post all the world’s links on the subject, and that still won’t change the irrefutable FACT that no evidence exists to support the claims made in those links, and the largest, most powerful and the wealthiest food and drug administrations in the world have all found the claims in those links to be false.

        Yes… some people may get headaches from Aspartame. And some may get diarrhea and other stomach unpleasantness, but the percentage of those people compared to those that experience no such problems is so miniscule that it’s statistically irrelevant. There will be people everywhere that can’t handle certain types of food. My body can’t properly handle dairy, raw cow or anything overly deep fried. That’s just how my body works (or doesn’t work, rather), but that does not on it’s own mean that milk, beef and fat are unsafe for consumption.

        As for the concepts of Food Reward theory, and the links you have posted and asked me to read, that has absolutely no bearing on my objections to THIS issue. Food Reward theory does not make diet soda drinks bad for you. The problems of Food Reward are a totally different subject of debate, and one that I am in agreement with you on, as I am with most of the things I’ve read by you.

        Let us agree that we very much disagree on this issue.

  42. ProudDaddy says:

    Arni, ask yourself this: Why hasn’t the artificial sweetner industry sponsored human RCTs like the one in rats I have referenced? When they dare to do so, we can talk again.

    • Arni Vidar Bjorgvinsson says:

      I don’t know about that ProudDaddy, but if I were them I sure wouldn’t waste my money on what amounts to basically trying to prove my innocence. I thought that human society functioned on the principle that you are innocent until proven guilty.. not the other way around.

  43. Richard says:

    I didn’t realize people were so passionate about diet soda! I’m down to mostly water and an occasional diet soda which hopefully soon becomes not even occasional. Even if it were proven somehow that diet soda (or regular for that matter) wasn’t harmful it is at best of no nutritional value whatsoever.

  44. I’ve been reading your blog backwards (most recent post up to this one) and I really liked that you employ logic and scientific evidence to back up your beliefs. Then I came across this.

    Why would you post a story that obviously is a correlation and not causation? There is no control for these studies (of course people who drink diet tend to be overweight) and that shouldve been more emphasized throughout your post. I’m loving the rest of your posts but this one reads like a good morning america/CNN article. You should amend it with the fact that none of those studies were controlled.

    • Well the studies correct for confounding factors, which does give them some weight. Plus they all point to the same conclusion, which is a highly significant, strong association.

      I agree that I should perhaps have used different words, but I’m not going to change it until it has been proven wrong.

      I’m looking forward to the day when the controlled trials in an ad libidum setting will be performed. If proven wrong, I will gladly update the article and apologize to my readers.

      There is actually a post coming up real soon about artificial sweeteners and how in a controlled setting artificially sweetened beverages may increase food intake compared to water.

    • Arni Vidar Bjorgvinsson says:

      Agree 100% Steven. The rest of the blog seems to be very well thought out and extremely well written.

  45. Okay guys, you win :)

    To the bottom of the article, I have added:

    “[Update 26/5/2012]: As some readers have correctly pointed out, the studies above only show that there is a correlation between diet soda and disease. These are not controlled trials and do not prove anything. I apologize for any misunderstanding.”

    Thanks for the interesting discussion, I will be more careful of the words I select in the future.

  46. Helgi S. Karlsson says:

    Hello Kristján

    I’m sorry to point this out, but with you being a man of science I’ll know that it won’t be taken personally.

    Kristján said:
    “I agree that I should perhaps have used different words, but I’m not going to change it until it has been proven wrong.”

    This is basically a “backwards thinking” in the establishment of truth. This is like saying “I’m going to apply the medicine until someone dies, then I’ll know it’s bad and I’ll stop”.

    You even encourage people to send this article to friends and relatives, with it being something more like a weather prediction than actual and factual truth. Like you in this article, weather reporters have factual data, however can’t establish a true causational connection, therefore it’s titled “prediction”. This article however, is written as an established truth.

    I also want to complement you on most other articles I’ve read and you’ve written. It’s been both a fun and informational read.

    • Thanks for the comment.

      I actually rather think the backwards thinking would be to put something on the market for worldwide human consumption, then waiting for it to be proven harmful, without the artificial sweetener industry willing to fork out the cash to fund the large studies.

      Then saying to avoid it until proven safe would be kind of backwards-backwards thinking, basically the correct way to think about it in my opinion.

      “Innocent until proven guilty” does and should apply to law, but I don’t think it should be applied to artificial chemicals meant for large-scale human consumption. In that case, “guilty until proven innocent” is more appropriate, as it is with pharmaceuticals, which must go through a rigorous process before being cleared for clinical use.

      But I’ve made some changes to the article. The numbers are there, but as pointed out the epidemiological studies do not prove an association.

      What do you think about it now?

      • Helgi S. Karlsson says:

        The funny thing is, that I actually do agree with you about putting stuff like artificial sweeteners on the market without proper testing is also a “backwards way of thinking”. However, the cases are different. On the other hand we have one of hundreds, if not thousands of consumable products put on the market without proper testing. People are aware of this to some extent. They are also somewhat aware of being cautious when it comes to buying products in general, because it is basically general knowledge that people try to profit by any means necessary. Therefore people are more aware of the “risks” involved with consumption in general.

        The main difference in this is where the information is coming from. You are a doctor and you are giving advice to people. People look to you as the “voice of reason” in health matters and tend to trust your knowledge with a “a doctor said so” attitude. Therefore, you have a responsibility to your readers to have your advice as sound as possible, and not assuming results that are not scientifically proven by rigorous standards. Otherwise you, and others in your (and my) profession run the risk of loosing peoples trust. The world is full of misleading information already, therefore doctors, psychologists, and other healthcare professions have a larger responsibility than ever of providing information that is “the best there is” at that point in time.

        I must however compliment you on your changes to your article. Now it doesn’t have “this is a confirmed truth” statements in it and therefore is a much more scientific and accurate read.

        Thanks for listening to reason and having the confidence to apply it.

        • Kristjan says:

          Actually I’m just a med student, not a doctor yet :)

          • Helgi S. Karlsson says:

            I see, well I’ve noticed how little people seem to differentiate between the two, that is “student” of a certain profession and a “certified physician”, so caution applies in both cases :)

  47. Let’s please use more exact language, even in a blog post. The musing “perhaps it’s got something to do with the insulin response generated when sweetness hits the tongue…” just can’t go un-responded-to. With very few exceptions, nearly all diet soda is sweetened with aspartame. There is NO peer-reviewed study, NONE, that has shown that aspartame affects insulin levels at all. Quite the contrary, all the studies have documented that aspartame does NOT affect insulin level. In fact, no non-debunked or non-questionable study has ever found any deletorious effect from aspartame at all. If you drink less than 15 cans per day of aspartame-laced soda water, drink it with confidence. And, no, I do not work for, or have any connection with, anyone or any entity that has skin in this game. I’m just for truthfulness.

    • In a later comment I acknowledge that AS do not raise insulin. It was wrong of me to say that and I didn’t know it at the time I wrote the article. I’ll remove it now.

      But the fact remains that there is an association between AS (including aspartame) and weight gain/disease in several epidemiological studies. These aren’t “questionable” studies and they are published in respectable journals like Nature.

      They do not prove causation though, but definitely suggest that this is something that needs to be studied further in order for diet soft drinks to be cleared for human consumption.

      Here, check out this article published in the Yale Journal of Biology and Medicine, where en obesity researcher discusses the possible link between Artificial sweeteners (including aspartame) and weight gain. As we know, weight gain leads to disease.

  48. Hi,
    Im afraid I work in finance (yawn!), have read this article, the replies and the links and some of it goes above my head so if I can ask a couple of things based on my understanding? I do drink quite a lot of Diet drinks, I didnt really think they were particularly healthy, I did honestly prefer the taste (no sugar coating on my teeth compared to ‘fat’ coke for e.g.) , but didnt think they were unhealthy as such. I dont actually eat loads either, so I dont think drinking the diet sodas has increased my appetite as some lines of the various articles suggest (not saying they’re wrong, just not in my case).
    But what I wanted to confirm, is that your article is suggesting (I know the tests have not been proven or whatever it is that makes the studies official, you are just letting people make up their own mind) that regardless of whether the diet drinks are increasing appetite they could still lead to a weight gain. If my reading is correct, the diet drinks could affect metabolism. I have read the diseases that they may cause etc but my main interest is the weight gain. I do struggle with weight – No, Im not searching for a miracle cure other than Im a fatty :-) I dont eat a lot of sweets etc, but do eat extremely late at night (work unfort) which is one of the main reasons for my weight problems. But I have gone through a period (about a year) of continuous weight gain and seeing as though nothing has really changed in my diet, I was wondering if this could be the cause. I definitely think I need to give up drinking Diet drinks as much regardless, but wondered if it could be a cause of my weight gain. I do also drink alcohol too much, and used to drink it with Diet coke to reduce calorie intake and carry on drinking without putting on so much weight….but it appears I could be wrong in doing this!
    Thanks for this article, interesting and very surprising.

    • Arni Vidar Bjorgvinsson says:

      Considering how fattening alcohol is, I’d suggest you start cutting back on that before you start cutting back on diet drinks. Alcohol at least has been proven without a doubt to be extremely bad for you. :)

    • The only way to know is to cut out the diet drinks for a month or two. I’d also consider your alcohol consumption, it can make you gain weight as well as harm your health in a thousand other ways.

  49. I would like to see more research on this. To see if the diet soda itself caused the weight gain OR was it the mind set of those thinking they could eat more if they drank a diet soda or did the diet soda increase their appetite. None of these studies answered these questions. Also this statement: “(one study) discovered that consumers of diet soft drinks were 65% more likely to become overweight and 41% more likely to become obese, during a seven to eight year period. Regular soft drinks did not have any significant effect. Another study of over 80 thousand women discovered that consuming artificial sweeteners contributes to weight gain.” That’s very misleading because those more inclined to drink diet drinks or use artificial sweeteners tend to have weight problems. They either have a tendency to gain weight or are constantly struggling with it. Most people who aren’t overweight aren’t going to be concerned about consuming diet food. Now if these studies can show they had different groups, one consuming diet drinks and artificial sweeteners and the other consuming non diet foods and both groups STARTED out at the same weight (and also keeping track of their food intake), then you could determine if the diet foods were culpable or was it those consuming these products going off the chart eating fattening food WHILE they were using artificial sweeteners and diet foods. And were those who were eating non diet foods, were they more prone to exercising. There are too many elements that were not known that could have caused the weight gain that had NOTHING to do with the diet foods. I am more inclined to believe that the reason why there are so many people who appear to gain weight while consuming these diet foods is because they’re the ones that are at risk to gaining weight who are attracted to these diet foods.

  50. Jack,

    I have been trying to lose weight for a while to no avail. The only constant has been my regular intake of diet coke. I would like to cut out diet coke completely to see if this will help with my weight loss attempts. The only concern I have is a lack of caffeine. I am afraid I wont be able to function—especially since i work full time as an assistant to an exectutive in healthcare administration and am going to school full time to earn and MBA. I also have two small children in preschool. I am confident i can give up diet coke but what are your reccomendations in the way of coffee—i am not sure i can drink without artificial sweetner. Would love to hear your suggestion. Good article–the mean comments are from those who are only in denial.

  51. Hey Ashlee,

    As a current caffeine addict, and one who’s weaned themselves off it in the past I can offer you a couple of approaches.

    First off you could replace your coke with coffee or green tea (Kris has a done a couple of great articles about these), that would keep your caffeine high, and let you remove your poision, sorry, artificial sweetener.

    Or you could cut down, plan to cut it out and let your adrenals recover. When I’ve done this in the past I’ve had an enormous headache for a couple of days, unless I cut back slowly and don’t go cold turkey. Anyone who doubts how strong caffeine is should go cold turkey and see how much your body likes it!
    To support your come down you might want to supplement with a good strong b vitamin complex, gram doses of vitamin c and perhaps an adrenal support formula. Other people I’ve helped through this have also used iodine formulas with great success.

    Feel free to ask any more questions.

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