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?”

The second most popular question: “What actually happened at the end of ‘Interstellar’??” has yet to be answered.

Back to Diet Coke. 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 for us 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? I’ll tell you soon, after a word from our sponsors.

Just kidding, we don’t have any sponsors. Although I wrote about this subject six years ago, it’s time to revisit the topic: Is Diet Coke bad for us?

The answer is…maybe.

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.

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!