Is Diet Coke Bad For You? What About Artificial Sweeteners?

There’s one question we get asked probably more than any other:

“Is Diet Coke bad for you?”

I get why this has caused so much confusion and debate. We all know sugar is worse for us than Darth Vader, so Diet Coke, with NO sugar, has to be better for us.

However, we’ve also been told Diet Coke is packed full of chemicals like aspartame that do all sorts of awful stuff…which would then make Diet Coke worse than Jar Jar Binks, right?

What’s the truth? Does the lack of calories in Diet Coke help us? Do the chemicals and other additives make it a horrible beverage choice

The answer is…maybe, but it’s not that simple.

Regardless of whether or not you drink diet coke once a month or you drink a twelve pack every day, it pales in comparison to the impact your diet will have on your weight.

For a lot of rebels who come to Nerd Fitness, the question on whether or not to drink Diet Coke instead of regular sode (or even water) is part of a bigger problem they are spending time on – “What should I be eating and drinking? How much? And when?”

In other words, this is a small piece of a much larger puzzle: “I want to lose weight, I’m trying to be healthier by drinking Diet Coke, but I need the caffeine and I work in a high stress job. HELP ME, STEVE!”

I can hear you yelling at your computer or phone right now.

Today we’re gonna get into the science of Diet Coke and aspartame, but I’d be remiss if I didn’t mention a program that is helping busy people like you who struggle with sugar cravings, buckets of caffeine, and are also trying to lose weight! All of these things are connected, and it’s why we started our 1-on-1 Online Private Coaching program: no judgment, no guesswork – just guidance from a NF coach who will help you navigate a busy lifestyle with nutritional instruction and handcrafted workout routines.

Schedule a free call with our team so we can get to know you and see if we’re a good match for each other! Just click on the image below for more details:

Okay, let’s get into the science of Diet Coke!

Diet Coke doesn’t make you fat…

Coke case

Diet Coke does not make you fat…directly.

As pointed out in this exhaustively extensive article from my friends over at, Diet Coke and other zero-calorie beverages do not inherently cause weight gain:

“There are no studies that indicate any long-term health risks from drinking diet soda. Diet soda (defined as calorie-free carbonated beverages sweetened with aspartame, sucralose, acesulfame-potassium, or other non-caloric or minimally caloric sweeteners) is not harmful to health, well-being, or body composition.” 

We’ve already covered in a previous article “Is a calorie a calorie” that consuming fewer calories is the first step in a process to losing weight.

Consuming a Diet Coke compared to drinking a regular Coke means you are consuming significantly fewer calories per day. If you consume multiple Cokes per day, switching to Diet Coke could result in thousands of calories less consumed each week.

There’s been quite a big discussion out there about the effect of artificial sweeteners on how our bodies react, specifically with insulin resistance and things of that nature.

However, this study suggests that artificial sweeteners don’t play a significant role in the secretion of insulin, compared to the consumption of regular sugar.

So what gives!? What’s with all of those studies and things we’ve heard about where people who GAIN weight while consuming diet soda? Although Diet Coke isn’t directly responsible for weight gain, it’s no innocent bystander either!

…But it’s No Saint either.

coke mirror

Diet Coke and diet sodas are kind of like the getaway driver in a bank robbery. Sure, they didn’t technically rob the bank, but they are guilty by association.

The reason we’ve heard diet soda can cause weight gain can be explained with this study:

“Although overweight and obese adults who drink diet soda eat a comparable amount of total calories as heavier adults who drink sugary beverages, they consume significantly more calories from solid food at both meals and snacks,” lead study author Sara Bleich said in a press release. “Diet soda is not making people fat,” Dr. Chris Ochner, who researches obesity prevention and treatment, said to CBS News. “Eating too many calories is making too many people fat.”

Diet soda might not CAUSE weight gain, but it is correlated with being overweight and unhealthy – people who consume diet soda often assume they are making healthier choices about their beverage (which they are), but as a result are consuming MORE food calories than they expected.

This is why you often see three Big Macs and a large fry accompanied by a large diet coke. Or why people get upset when they gain weight on a gluten-free diet, even though their diet is composed of gluten-free cookies, cake, muffins, pancakes, and pasta. These folks are missing the point!

Although we know correlation does not prove causation, it appears diet soda is causing OTHER issues beyond simply increasing our waistlines. Specifically, it can cause us to underestimate how much food we are eating, or lull us into a false sense of healthy security when it comes to consumption.

And from a behavioral and habits perspective, it keeps us needing something “sweet” in our lives.

There’s other thing I’d like to mention about diet sodas, as this is something that has become SO mainstream it’s almost taken as a fact….

what about aspartame?

coke back

If I told you “aspartame causes headaches and cancer,” you’ll likely respond in one of two ways:

  • What’s aspartame?
  • Of course it does.

If you don’t know what aspartame is, it’s an ingredient in Diet Coke that replaces sugar – it’s 200 times sweeter than sucrose so only a small amount of it is used. However, it’s been widely regarded by the public that aspartame is a cancer-causing agent and should be avoided at all costs.

What’s the truth here?

It turns out, aspartame’s association with cancer is much cloudier than you’ve heard.

For starters, there may be some truth to the rumor that aspartame can cause headaches for some people, though not nearly enough studies have been completed to prove this definitively and a placebo effect might be in place due to aspartame already being seen as the villain.

As far as aspartame causing cancer, this has also never been definitively proven.

Back in 1996, a study suggested there might be a link between the increased chance of developing a brain tumor and the consumption of aspartame, but this was proven false.

Also, a study in 2005 saw an increased risk of cancer development in rats who were fed aspartame. However, the results were inconsistent, and these rats were fed an equivalent of hundreds of cans of diet soda per day.

Finally, “NCI examined human data from the NIH-AARP Diet and Health Study of over half a million retirees. Increasing consumption of aspartame-containing beverages was not associated with the development of lymphoma, leukemia, or brain cancer.”

Note: this is not an endorsement of aspartame, but simply an attempt to shed some light on a controversial subject. If you are concerned about aspartame consumption, avoid it.

We’re confident that aspartame becomes a non-issue anyway. Why?

what does Nerd fitness say?


Our advice can be simple and straightforward: Don’t drink soda! It’s terrible for you. Sugary beverages (soda, fruit juices, etc.) can lead to weight gain, diabetes, metabolic syndrome, and a host of other issues. If you drink soda now, try drinking less. A twelve pack of Mountain Dew every day is NOT a good habit for you.

But you don’t need to change overnight. Try 11 tomorrow.

However, as we know drinking a lot of alcohol isn’t good for you either, be smart about how much and what you drink to make sure you don’t derail your healthy lifestyle. If you are jonesing for a soda, choosing a diet soda over a regular soda is a good start. Life is short, and if a single Diet Coke is going to make your day a bit happier and stave off a worse decision, go for it.

However, we don’t recommend you just replace soda with diet soda, and not change anything else (and expect to see drastic changes).

I want you to think about WHY you are consuming so much soda, be it regular or diet:

If you are consuming soda for the caffeine content, switching to diet soda is a tool to get started. Read up on our thoughts on caffeine here, but you’d be much better off with black coffee and green tea.

If you are consuming soda because you’re addicted to sugar, then we have a much bigger habit problem to deal with….but it can be dealt with.

We’re interested in permanent, antifragile solutions, and Diet Coke is a temporary hack to a much deeper-rooted problem: your source code when it comes to sugar or caffeine addiction. By fixing your code at the source, you can start to wean yourself off of sugary beverages and artificial temporary solutions.

Not sure the best way to change your diet, or tired of losing weight only to gain it back? You need a better blueprint strategy to follow! In addition to our Online Coaching program where you get personalized guidance and instruction, we have a 10-Level Nerd Fitness Diet treats the process like a game, and allows you to pick the level you’re comfortable with, and only has you leveling up after you complete a 2-week challenge.

Grab our Nerd Fitness Diet strategy guide when you sign up in the box below and join the Rebellion. Get healthy the right way. Get healthy permanently.

Long story short: we want to create long-term healthy systems that have us eating healthy foods and avoiding liquid calories. This is about building good strong habits, and keeping ourselves making healthy happy eating choices.

Although swapping out soda for diet soda is a solid step in the right direction, the true solution is retraining and rewiring our body so we don’t need to chase that sugar fix; we can slay our addiction to sugar entirely.

tl;dr – Soda is legitimately terrible for you. Sugar is Darth Vader. Diet soda can be a stepping stone between sugar addiction, the need for sugary beverages, and FREEEEEDOM:

What are your experiences with diet soda? Did you use them as a tool to help you lose weight? Or did you struggle with weight loss until finally dropping diet soda out of your daily consumption as well?

Leave it in the comments!


PS – Phew, if you made it this far, I want to share two ways you can get more in-depth training, advice, and help making fitness a priority. As we mentioned, our first is our 1-on-1 Online Coaching ProgramNo more shame, no more hiding what you eat, no more guesswork – you’ll get expert guidance and accountability from a professional on Team Nerd Fitness who gets to know you better than you know yourself!

Sound good? Head over to our Coaching page and schedule a free consultation to see if it’s right for you!

PPS: 40,000+ rebels have joined us in the Nerd Fitness Academy! If you’re interested in strength training and want more specific workouts to follow, nutritional advice and meal plans to pick from, a boss battle system, character leveling system, and a supportive community, check it out.  We’d love to help you level up with us.  See you inside!


photo pin: Sarah Korf: nutritional information, Ryan Hyde: Water, Mike Mozart: Diet Coke, Laura Lewis: mirror, Mike Mozart: Diet Coke

Get The Rebel Starter Kit

Enter your email and we’ll send it right over.

  • The 15 mistakes you don’t want to make.
  • The most effective diet and why it works.
  • Complete your first workout today, no gym required.
  • These are the tools you need to start your quest.
  • Frankie

    So, all things artificial must be good for you!!! I’ll buy some more of that on my way to get insulin and syringes at Wal-Mart.

  • Frankie

    So, all things artificial must be good for you!!! I’ll buy some more of that on my way to get insulin and syringes at Wal-Mart! Ha!

  • Frankie

    So, all things artificial must be good for you!!! I’ll buy some more of that on my way to get insulin and syringes at Wal-Mart.

  • chelsea

    My husband drinks so much diet coke or diet Pepsi a day that I’m worried he won’t see our two year old hit age 5. If I don’t have it in the house he goes out and buys it anyways. He also says we can’t believe every thing we see on the Internet. (Even though this all makes alot of sense.) I just wish he would get it because even though he isn’t sick yet it’s making me sick wondering what I’m going to do when I become a single parent.

  • Brad Rogers

    I’m addicted to Diet Coke and I really am waiting for an article that says – “YOUR OVERWEIGHT BECAUSE OF DIET COKE.” I don’t over eat because I drink diet coke. (ex of a big mac and large fries above) I think i really comes down to if I drink Diet Coke, I don’t drink water. And if you drink lots of water, your body releases it because it knows it will be replaced. If it is scared it doesn’t get enough water… it holds onto it. I probably have 7-10 of water on my body right now. Every time I quit diet coke and drink water only – I lose weight quickly (without changing diet) and my skin and waistline tightens up quickly.

    Anybody else experience this?

  • Matt

    I use diet ginger beer as a filling replacement for alcohol. I used to drink 2 or more glasses of wine with dinner each night and couldn’t shift the kilos, despite an otherwise healthy diet and exercise. When I stick to diet soda instead I’m finding both body weight and fat shifting fast. Although I do get the mentality that because you are doing something healthy you can give yourself a break when it comes to junk food occasionally – in reality, that’s a big fail.

  • Anton Hollfon

    I wrote my own post on this and I would be super happy if anyone read it 😀

  • Nutritionist

    Diet soda does link to weight gain. When you eat/drink something sugary/tastes sugary your body will release insulin at which point your body screams “give me sugar” because it was expecting sugar and didn’t get it. So you give it sugar… just not with the diet soda. Maybe it’s not the source of sweet calories, but it for sure gets the ball rolling by tricking your body.

  • Troy

    These comments are the stupidest shit I’ve ever read in my life. Almost everyone here missed the point of the article. Diet drinks do not have harmful side effects. You dumbasses don’t understand correlation vs. causation. Some of you are just straight up hysterical and need therapy for your imaginary maladies. You people really do give human beings a bad name. It’s genuinely sad how stupid you are. Stupid to the point that I don’t understand how you dress tourselves in the morning. Jesus Wept.

  • Troy

    Read the article you fucking idiot. And your stupid ass comment doesn’t even address what the guy you replied to said. Christ you’re dumb.

  • sar922

    25 years on diet coke still got all my teeth.
    been told by the doctor only 5% chance of heart attack or stroke.
    Draw back is can cause gout.

  • Billy Bob Joe

    Really well written article, nice read!

  • Jacob Hoffman

    Well. I need to lose more weight. And I was your 12 mountain dew guy. The cravings began as a thyroid condition undiagnosed for a very long time and worsened to diabetes.

    I went from 380 pounds to 250 in about a year and a half. I’m still on diet sodas but most of my sugar cravings are under control. The lure of diet sodas increases my desire for sugar by offering what I think I want and proving to my body I’m not getting it. If there is a real danger in diet sodas is that it definitely increases my appetite.

    The long and the short, I need some alternatives. I drink water mainly but it gets exhausting to have a one trick solution. Lightly sweetened green tea and coffees help but they have caffeine like what’s been mentioned. I’m at my wits end. I probably have another year before I am in a normal weight range.

  • Dave Powell

    I do not drink very much Coke and Pepsi anymore. Fist of all, the diet beverages taste like crap. Well perhaps I’ll rephrase that cause I have never sampled crap. They taste bad. Now, in the fifties, and sixties I remembered Pepsi, and Coca-Cola tasted much better…less sweet and lots of fizz. Do You know how many grams of sugar were in the beverages then, VS now? That would be interesting. Of course sugar is not good in too much consumption, But, now kids are for the most part, inactive, sedentary, and you bet they are going to become fat, and prone to health problems. We were active, playing, running, working, chasing. What’s the answer? Tell them…

  • Mark Hooley

    I used diet root beer to quit drinking alcohol and it worked. I also lost a lot of weight, 25% reduction in 8 months. Reduced BP and cholesterol to normal, no more pills! I, however drink 4-5 cans of diet root beer a day. Beside needing to pee a lot, I am in great shape.

  • Sue Chretien

    I have been drinking diet coke for years off and on, more on that off. I don’t drink tea,coffee or smoke and I drink alcohol very seldom. What I do find is that it goes way better with food that is bad for you than veggies and fruit. That is where I find for me it certainly isn’t a diet aid. Coke is probably in cahoots with the chip companies.If I could drink it without eating I’d be much better off. I do enjoy it though. thanks for the info

  • Fantasise

    I only drink diet coke because I love the taste.. I am on a diet at the moment, I just ate a small bowl of cereal (with very little sugar content and low in calories) and an egg separately. Diet coke doesn’t always have to be consumed with junk food, just enjoy the taste and control your eating habits people!!! Don’t blame it on the diet coke!!

  • Sabrina Eileen

    I used to drink a ton of coffee to stay awake for work and school. But after awhile it had a gnarly effect on my stomach. I’ve gone 80/20 in terms on diet soda and coffee and so far no stomach problems. I can get homework done and have yet to be fired

  • mark

    I swapped beer for diet cola, I was consuming too much beer every night and gaining weight rapidly. Since I quit beer I am now loosing weight. Don’t really enjoy coke but I missed the fizz in the beer! surly the diet coke is better than the beer?

  • Amreen

    ‘ I say we just accept the fact that with everything that “supposedly” causes cancer, we should just all expect to get cancer eventually’. I LOL’d

  • Jim Penny

    Diet soda is better for you. It has never killed anyone. Sugar kills more people than tobacco, and it’s bad press for the sugar industry, which is losing business. I wonder who is sponsoring the artificial sweetener “research”?

  • Jim Penny

    By the way, I drink diet drinks all the time, and have never experienced this so-called craving for sugar. My daily sugar intake is low, and since cutting out added sugar, my triglycerides have dropped, and my doctor said – I don’t know what you’re doing, but keep doing it.

  • Steven Ainsworth

    I don’t reckon, there is anything wrong with Diet Coke. Personally, I have drank the equivalent of between 4-6 cans a day for years, and I am capable to compete in marathons, half marathons and I am currently competing as a powerlifter with a heart rate of 48. And a 13 percent body fat. In my opinion, it is entirely made up scaremongering. ????

  • Tia Urgasova

    Interesting article, be good to see where the references came from and see the results for myself. Anyhow, I tend to have a can or a 500ml bottle of pepsi max/coke zero whenever I am craving something sweet. Especially after I’ve had a period of not caring what I eat and I try to get back on track with my health push and it seems to help me cut my sugar cravings by providing me with a little hit of caffeine. I know water is far better for you (and I still have 3-4l a day) but 2/3 sugar free sodas a week stops me from having 20 donuts on a saturday night 🙂

  • Smeejlad

    Great article – dispels a lot of alarmist tactics regarding diet coke.

    Overriding point is stop needing sweet stuff… refined sugar has only been in our diets for the last 200 years so our body is not adapted to dealing with it. If you want to keep the weight off, keep your fingers off the white stuff.

  • Susan Key

    This commentary was much more accurate than other sites. What I have found is that if you intersperse diet coke with water it will reduce your appetite. I only drink caffeine free but not sure the caffeine is really terrible for your. So mostly now I drink water & then treat myself with some caffeine free diet coke. I think that Diet Coke may stimulate your appetite. Water seems to have the opposite effect.

  • Moucheron

    I’m a 72 year old female and never had a weight problem. Never smoked (anything) or had a cup of coffee. When growing up, we never ate sandwiches but ate a vegetable plate for lunch and dinner, did not eat any packaged cookies, dinners or boxed cereals. I seldom have bread unless in Ireland and Germany and eat no sugar…but will have a slice of your birthday cake.
    I love Diet Coke and have a can several days in a week. I think I had a headache once as a child as that’s what my Mother said it probably was. So, the day I see a really well done study prove it will hurt me, I might consider quitting and I did say might.
    I’ve read a lot of studies and have never seen a thorough and not ridiculous one. I’ve come to the conclusion the government hands out grants for studies to idiots.

  • Pingback: Can Diet Coke Make You Fat? | Nerd Fitness()

  • Debbie Campbell

    I’ve been working on not drinking diet soda for about 3 weeks. I was drinking at least one a day, now I’m down to about 1-2 per week, and not missing it too much.

    What do you think about the liquid additives to water like Mio Energy (with caffeine) or Crystal Lite Pure, that don’t use aspartame? I’m finding them to be pretty good, and the Mio seems to give me the same caffeine fix as soda.

  • Grumbleshark

    Thank you for not demonizing sweeteners or peddling woo. 🙂
    I have to listen all day to how my PowerAde Zero is going to give me cancer, as well as the cell phone I run with in my sports bra. Cancer cancer cancer.

  • I freaking LOVE YOU STEVE!!!

  • Karol

    I’m so glad that I was born in a post-Soviet country in which soda’s popularity was very scarce as I was growing up and then I started reading Nerd-Fitness, so I never have had problems with it. I feel sorry for the state your country noutrition industry is in. Good luck fellow Nerd-Brothers!

  • Steve Joselson

    Thank you for the info. I drink about 2 liters of diet soda per day. With caffeine before dinner and caffeine free after dinner. I just enjoy soda and drink diet for the lack of calories. I still watch what I eat and try not to eat more because I am saving on calories but also feel I can have an extra snack once in a while but probably would have it either way. I appreciate the balanced story.

  • lerlo

    I am not an overweight person but prefer diet soda over regular, drinking 1 to 2 cans per day. I’m sure it’s not the perfect beverage, but alot of sugar is proven to be bad, so until there is proof that it’s bad I will continue enjoying it. Everything in moderation.

  • robert hingston

    Everything as sweeter these days so we need to scrutinise them Products as well..
    Diet Coke does have a lot of salt and caffeine so in some ways a Diet Coke is like a Cold black carbonated coffee with salt and sweeter..
    So if your going to drink a lot of Diet Coke make sure you dont have a lot of salt or caffeine in other products..

  • Pingback: I used to work for the sugar industry. | Nerd Fitness()

  • ThaDrunknGamer

    this is actually a great article. all the others i read really seem they were paid for. this just seems honest.

  • Jacob

    The only reason i drink diet soda is because I’m a diabetic. I have been a type 1 diabetic my whole life. Drinking Diet pop safes insulin…. LOTS of insulin. Insulin is really expensive… thank god for insurance. I hate people who make fun of me for drinking Diet soda. If you were in my shoes, you would understand. I’ve been drinking Diet pop for so long that regular pop taste really bad to me.

  • tg3

    That pre-diabetes shit has been debunked. Aspartame is safe, diet sodas are safe, if you like them, drink them. If you don’t, just avoid them. But stop spreading lies about it.

  • Pingback: URL()

  • Pingback: Boliden()

  • Pingback: agen poker()

  • Blobulent Republican

    Correct. This article is a mewling mess and about 48% pseudo-Science. They should’ve stopped with “there’s no Scientific correlation, period”. Psychological addictions or Sodium making you thirsty belong in behavioral studies not withstanding, those other assertions are the scientific equivalant of “The Twilight Zone”. Where “anything can happen, for any reason or no reason, at any time or all the time”. Like that Serling guy said: “You unlock this door with the key of imagination. Beyond it is another dimension: a dimension of sound, a dimension of sight, a dimension of mind. You’re moving into a land of both shadow and substance, of things and ideas. You’ve just crossed over into: “The fake Science and Confirmation bias” Zone. It’s sad that the Internet has brought us to this low place.

  • Larry

    For the same reasons you site, I get tired of all the fake-science reports that things (like aspartame and GMOs) are bad for us. Industries have been destroyed by false, or at least questionable, information being passed off as fact. It seems to me (an overweight food addict) that moderation is likely a key to avoiding unhealthy habits. Unfortunately, those more able to moderate don’t have the problems of addictions, and will likely not be on this site.

  • Martin Stewart

    The reason for non weight loss drinking sodas or other liquid drinks may be that the liquids actually dilute the acid content in the digestion of the foods intake thus takes a lot longer to digest
    I drink 20-30’mins before I eat and 20-30 mins after I eat
    Thus allows my system to digest what I eat hope this may be useful by the way I am O neg blood group might be a good idea to read the Book Eat For your blood type by peter dadamo

  • WentHulk

    I feel no real guilt consuming small amounts of diet coke on occasion but I’m getting sick of people telling me I should stop drinking it.

  • Calista Young

    Why do they have to start with a 2 liter bottle a day? Lmao

    Overall, I like some of this article, but not everyone who drinks diet sodas aren’t THAT intense. Do you really think one 12 ounce can is equivalent to one 2 liter bottle? Even if you drop diet soda completely, this article even states itself that diet (food choices) is overall more important than how much zero calorie beverages you consume.