Is Diet Soda Bad for You? (Should I Drink Diet Coke for Weight Loss?)

You asked for it: it's now time to learn all about diet soda.

There’s one question we get asked more than any other: “Is diet soda bad for me?

People want to know if Diet Coke will make them fat and make them sick, or if it’s all just a bunch of hoopla about nothing.  

We help our clients navigate challenges with soda (diet or not) in our 1-on-1 Online Coaching Program, and we’re gonna tell you everything you need about diet soda below.

Here’s what we’ll cover:

Let’s get right to it!

Does Drinking Diet Soda Lead to Weight Gain?

How much of this Diet Coke, should you drink, if any?

Does drinking diet soda make you fat?

No, it does not.[1] 

It would be super evil if it did, what with the whole “diet” thing and all.

Diet sodas utilize “high-intensity sweeteners” which is a fancy term for very-low-calorie (or zero-calorie) sugar substitutes:

  • Acesulfame Potassium
  • Advantame
  • Aspartame
  • Monk Fruit Extract 
  • Neotame
  • Saccharin
  • Sucralose
  • Stevia 

The FDA has approved these eight high-intensity sweeteners for human consumption.[2] You’ll find them in all sorts of food products, not just diet drinks. 

Because high-intensity sweeteners are many times sweeter than table sugar, you can make a drink taste “sweet” without including any sugar at all. 

Most important, without the sugar, you’re skipping out on all the calories that come with it.

Weight loss depends on consuming fewer calories than you burn, so drinking Diet Coke compared to regular Coke can help tip the equation in favor of “weight loss.”

  • 12 oz Diet Coke total calorie count: 0
  • 12 oz Coca-Cola total calorie count: 150

If you’re trying to lose weight, but love fizzy carbonated and caffeinated beverages, the soda with fewer calories seems like a no-brainer.

Gif that says "seems legit"

“Steve, hold the phone here! Are you saying Diet Coke is okay to drink? I thought the sweeteners and chemicals in it were sketchy!?!”

The concern of drinking diet soda generally rests on three points:

  1. Drinking diet soda will make you crave real sugar.
  2. Your body processes high-intensity sweeteners just like actual sugar.
  3. Artificial sweeteners (like aspartame) can make you sick or cause cancer.

We’ll hit each of these points with its own section below.

Before we continue, I need to make a strong caveat: most studies on diet soda treat all high-intensity sweeteners as one.[3] This is concerning considering there are eight approved high-intensity sweeteners in use.

Does your body process all eight the same? 

I get it Barney, this diet soda stuff is a bit confusing.

Some early studies on various sweeteners do show our bodies process them differently.[4]

More studies are being done on individual high-intensity sweeteners as we speak, so expect new information on the subject to unfold.

For now…

Will Drinking Diet Soda Make Me Crave Actual Sugar?

Does diet soda make you crave actual sugar?

If you eat a bunch of sugary and sweet food regularly, your body can start to crave more of it.[5]

In other words, consistently eating sugary foods in the afternoon can result in an urge for sweets after lunch. 

These cravings can make it difficult to turn down the bowl of M&M’s as you pass Debra’s desk (She’s even got the peanut kind!).

If you eat a lot of candy, you'll soon want to "feed" this craving.

The question becomes, do the high-intensity sweeteners found in diet soda make us crave sugary foods?

The research on this isn’t clear: 

  • Studies done on rats have shown a positive correlation between high-intensity sweeteners and sugar cravings.[6]
  • A 2019 meta-analysis found two studies where aspartame was added directly to the diets of humans. The result? Those who consumed the high-intensity sweeteners found their sugar craving to be LOWER.[7]

There might be something to the thought that drinking a Diet Coke can help satisfy the sugar craving.

As long as you remember: “correlation doesn’t prove causation!” 

Anecdotally, many of our coaching clients claim that grabbing a diet soda helps them from drinking the regular sugar-filled version. This can be really important, because “cravings” are one of the top issues facing most of our clients.

Which is why we work closely to identify possible food addictions in our 1-on-1 Online Coaching Program, so we can start to work through them together. Our strategy is to take it slow, to make small changes to alter these cravings. Over time, this is the best way to see real progress. 

If you’d like to learn how we can help battle sugar cravings, click below:

Does My Body Process Artificial Sweeteners Just like Sugar?

It's time to learn if our hormones treat high-intensity sweeteners like they would regular sugar.

Another concern of drinking diet soda rests on the idea that your body processes high-intensity sweeteners as it would normal sugar.

The argument states that these sweeteners are so sweet that they fool your body into thinking it’s consuming actual sugar. 

After drinking diet soda, your body responds as it would after consuming normal table sugar: by dumping out insulin. This slows down the fat-burning process.

That’s the gist of it, more or less.

Is it true?

Do high-intensity sweeteners trick our bodies into releasing hormones (insulin)?

Again, the studies on this are mixed:

  • The high-intensity sweeteners sucralose and saccharin were both shown to provide a small insulin response in men.[8] 
  • Aspartame does not appear to elicit the same hormone response.[9] 


I'd say don't stress too much on the insulin response of diet drinks.

This isn’t a HUGE deal. Of all the things to worry about with regards to weight loss or getting healthy, this doesn’t hold the top spot on the list.

While hormones do play a role in weight loss, the main determining factor will always be an energy balance (calories in vs. calories out).

Since most diet sodas have next to zero calories, I’d say the insulin response of high-intensity sweeteners isn’t that important for your weight loss journey.

There are far better targets in the quest to eat healthy, like eating lots of vegetables and eating enough protein at every meal.

Can Drinking Diet Soda Cause Cancer? (Is Aspartame or Saccharin Dangerous?)

Are the ingredients in Diet Coke sketchy? Let's find out!

The other concern people have about diet soda is that it will cause cancer and kill them and everyone they know.

A little hyperbolic perhaps, but…

Should we be worried about the ingredients of diet soda causing us harm?

Some history is in order:

In the 70s a high-intensity sweetener (saccharin) was shown to give rats cancer.[10] People flipped out and actually banned saccharin in America, although it’s since been reintroduced.

Why the reintroduction? 

Because no cancer link has ever been shown for the human consumption of saccharin. And folks have looked.[11] A lot.[12] 

Not everything that is cancerous to rats is harmful to people, and vice versa. 

Plus, you would have to drink 800 cans of diet soda to get to the levels of saccharin given to the rats in the study.

Even an all-night binge of Call of Duty would only put a small fraction of a dent in that.

Diet Coke is a notorious aid in the late-night gaming world.

How about aspartame or any of these other high-intensity sweeteners…

Are they sketchy?

Earlier I stated the FDA, the United States’ regulation agency, approved eight high-intensity sweeteners.

They aren’t the only agency that has done so. Australia, the EU, Japan, and Canada have all reviewed and approved these sweeteners.[13] They did so after a thorough investigation. 

Despite looking for issues, regulating agencies have found no harm in high-intensity sweeteners.

So it’s safe to say that high-intensity sweeteners are okay to be used in a reasonable amount.

This brings up the question…

How Many Diet Sodas Can I Have in a Day?

Can you drink an entire 2 liter in a day? More than one? Let's find out!

While the sweeteners in diet soda have been approved safe for human consumption, there is a limit to this approval.[14] But I won’t make you pore over charts and do the math…I’ll do that for you.

What’s the number of 12-ounce diet sodas deemed safe in a day?


Which is A LOT of diet soda. 

However, it should be noted that diet soda is not the only place high-intensity sweeteners are found. 

Many other food products utilize these sweeteners to cut back on sugar and calories. So keep an eye on protein bars, yogurts, baked goods, etc, for hidden high-intensity sweeteners.

The other concern with drinking lots of diet soda would be the caffeine. Caffeine in moderate amounts is fine, but if you go overboard you could increase your anxiety and interfere with your sleep.[15] 

Yeah, maybe it was too much Diet Coke...

There’s about half the caffeine in Diet Coke versus a regular cup of coffee, which is still a decent amount. 

If you have trouble sleeping at night, consider how late in the day you’re having your last can of soda. Perhaps install a 2pm “caffeine cutoff” if you find yourself tossing and turning at night. 

Another problem with diet soda: most of them contain exactly zero nutrients. It’s water, some kind of sweetener (sugar or not), flavoring, coloring, and carbonation.

Drinks like coffee and tea actually have some antioxidants present, so you might be getting some benefits with these caffeinated drinks.[16] 

If you find yourself drinking lots of diet soda, consider mixing in some coffee or tea as a partial replacement. 

Sparkling water might help with the switch too, if you love those fizzy bubbles.

At this point, we should note that stopping diet soda consumption might be easier said than done.

Can You Be Addicted to Diet Soda?

Is Gollum addicted to Diet Coke AND the Ring?

Anecdotally, it does appear that drinking diet soda can be “habit forming” for some people. 

CNN explored the issue and found numerous people who consumed more than a six-pack daily, “easy.”[17]

“Addiction” is a word that gets thrown around too much these days, so I’ll stop short of making a medical classification on these folks. Plus, I searched the scientific literature and couldn’t find any studies on diet soda addiction.

However, if you stockpile Diet Coke like it’ll be currency in the post-zombie world, you’re not alone.

This “addiction” makes sense considering the beverage was designed to hijack your brain’s reward system.

Yeah, diet soda can indeed hijack your brain's reward system.

The Coca-Cola Company hires folks to find the perfect combination of:

  • Carbonation. The bubbles actually burn your tongue a little, which provides a pleasurable experience. Kind of like a good hot sauce. 
  • Sweeteners. Sure, it isn’t sugar, but your brain likes them just the same.
  • Caffeine. The jolt from caffeine will provide you a boost and raise your dopamine levels. The brain likes this.
  • Flavor. After drinking Diet Coke for some time, your brain will start to associate the flavors with carbonation, sweeteners, and caffeine. Which will make you start craving the flavor of Diet Coke. This is probably part of the reason people become brand loyal to particular diet beverages. 

How do you know if you have an addiction? If you find yourself approaching our 18 can a day safety limit, that’s definitely a sign. 

Another would be if you find diet soda interfering with your life (not sleeping after drinking Diet Coke all evening).

You don’t have to go cold turkey on this one: 

  • If you normally drink six cans of diet soda a day, try five.
  • After a month or so of this, try four.

This is the exact strategy we follow with our 1-on-1 Online Coaching clients, and it’s the most likely to succeed. 

Small changes over time are the ticket to permanent success.

Is Diet Coke Worse for You Than Regular Coke?

Are Diet Coke and normal Coke the same, health-wise?

Before you use this article as justification to start drinking a six-pack of Diet Coke a day, let’s talk about some other possible concerns.

We’ve talked about all the mechanisms in diet soda that can make it unhealthy (high-intensity sweeteners, caffeine, etc). My conclusion is that these factors are likely overblown.

However, we should acknowledge that drinking diet soda can often be linked to health issues:

  • Despite diet sodas containing low to zero calories, drinking them is correlated with obesity.[18] Is this just because people who are overweight are more likely to consume a “diet” drink? We don’t know.
  • Diet soda consumption has been associated with kidney disease.[19] Is this because of the high phosphorus content of diet soda, or because people who drink soda likely have a poorer diet than those who don’t? This has still yet to be answered.
  • Soda, even the diet version, isn’t great for your teeth.[20] Diet sodas are acidic, leading to the erosion of tooth enamel. Although to be fair, this study found the acids in orange juice more corrosive than Diet Coke.[21]

There’s an important point here: drinking regular soda is also linked to kidney disease, teeth erosion, and obesity. Even more so those last two points (because of all the sugar and calories).[22] 

So the concerns of drinking diet soda would also be found in drinking regular soda…even more so.

Drinking Diet Coke may be the lesser of two evils here. 

Is Drinking Diet Soda Bad for Weight Loss? (Next Steps)

At the end of the day, prioritize water over diet soda, but don't stress about the diet soda.

If you’re starting your weight loss journey and wondering where diet soda fits into the picture, I want you to know I’m proud of you.

You’re starting to ask questions and you’re looking for answers. This is a great first step.

If you’re trying to lose weight and currently drinking regular soda, the switch to diet would be a good move. 

You’re gonna consume fewer calories that way, critical for weight loss.

This is why one of our top recommendations to our coaching clients is to cut back on sugary drinks. 

However, if you currently drink diet soda and are trying to lose weight, there might be some better targets to shoot for:

These are far more important than an occasional Diet Coke here and there.

If you find yourself firing on all cylinders (you eat well, you strength train, you get lots of sleep), then maybe consider replacing diet soda with tea, coffee, or carbonated water. There are enough unanswered questions on consuming diet soda to warrant the switch. 

The most important thing you can do now? Commit to a change:

  • One less regular soda a day
  • One less Diet Coke a day
  • A daily walk first thing in the morning

Pick something you can track. Something with a clear “yes or no” that you can reflect on at the end of the day.

This will help you start your weight loss journey.

It's now time to take some action on your weight loss journey. You got this!

Want some help getting going? A little nudge out the door?

Okay, but only because you’ve been nice this whole time:

#1) Our 1-on-1 Online Coaching Program: a coaching program for busy people to help them make better food choices, stay accountable, and get healthier, permanently.

You can schedule a free call with our team so we can get to know you and see if our coaching program is right for you. Just click on the image below for more details:

Your NF Coach can help you lose weight and get healthy!

#2) If you want an exact blueprint leveling up your nutrition, check out Nerd Fitness Journey! Our fun habit-building app helps you exercise more frequently, eat healthier, and level up your life (literally).

It’ll also provide a step-by-step plan from moving away from regular sodar, perhaps to a diet version or even tea.

Try your free trial right here:

#3) Join The Rebellion! We have a free email newsletter that we send out twice per week, full of tips and tricks to help you get healthy, get strong, and have fun doing so. 

I’ll also send you tons of free guides that you can use to start leveling up your life too:

Alright, I think that just about does it for me.

Now, your turn!

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?

Share your story in the comments!


PS –

Check out the rest of our sustainable weight loss content:

PSS: I want to give a hat-tip to Precision Nutrition, whose fascinating article served as the inspiration for this post. 


Photo source: Corrie Miracle: Diet Coke, Zeyus Media: Sugar Spoon, Stavos: ScientistEmmi: GollumSarah Korf: nutritional information, Ryan Hyde: Water, Mike Mozart: Diet Coke, Laura Lewis: mirror, Mike Mozart: Diet Coke


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