Diet Soda and Fatty Liver Disease: Can You Drink It?

Is diet soda allowed if you have fatty liver disease (MASLD, previously called NAFLD)? This is the million-dollar question that I’m going to answer today – and it’s not going to be easy!

There are two sides when it comes to fatty liver and diet drinks and, as you can imagine already, they are both at opposite poles.

One side claims that drinking any sort of diet soda if you have a fatty liver will do you more harm, while the other claims that it’s safe to drink these beverages if you have MASLD, or at least better than drinking regular soda.

Before getting into the details, one thing is certain: if you have a fatty liver, not drinking any type of soda – with or without sugar – is the best approach.

This is the only way to eliminate any potential risks associated with the artificial (or natural) sweeteners used in these products.

I already offered a bunch of ideas on things to drink if you have fatty liver, and, as you will see in that article, options are not limited, even if you skip the soda completely.

But what if you’re like most of us people out there and you really love your Diet Coke or other unsweetened drinks? Wouldn’t it be safe to consume, since there’s no sugar in it and it’s the sugar that is bad for your health?

Let’s jump in and read all the details!

What’s inside your “zero sugar” soda

Most diet sodas replace sugar with artificial sweeteners like aspartame, sucralose, or acesulfame potassium (Ace-K). Some newer brands use stevia or monk fruit extract, which are claimed to be better tolerated. But more research is still needed.

Aspartame: the biggest problem

Aspartame has been controversial for decades, even though major organizations like the WHO and FDA maintain that it’s safe for humans within the acceptable daily intake – up to 40 mg per kilogram of body weight per day.

So, for a 70-kg (155-lb) adult, that’s around 2,800 mg per day. A can of Diet Coke and other similar drinks all have around 200mg of aspartame per a 12-ounce can (350ml).

Based on this alone, it means that even if you drank 10 cans in a day, you’d still be under the limit. Of course, that’s not a green light to start chugging them, especially since in 2023, the World Health Organization’s cancer research arm (IARC) classified it as “possibly carcinogenic”.

At the same time, a Chinese study found that aspartame increases the risk of liver cancer – which is definitely not something to ignore.

Looking at some more studies, we have an interesting finding from a study from 2015. Made on thousands of participants, the study concluded: “We observed no significant association between diet soda intake and measures of fatty liver disease.”

This is encouraging, until you read the findings of a different study, from 2008 which claims the exact opposite: “The findings of the present study suggest that soft drink consumption is the most common risk factor for fatty infiltration of the liver in patients without classic risk factors.”

However, this particular study is focused on all soft drinks, and not just diet variants (although these are included).

So my recommendation is to stay away from it as much as possible – ideally, eliminate it completely from your diet.

Other sweeteners

Aspartame is not the only artificial sweetener used in diet sodas. There are many options and mixtures out there, from ones that are considered safe (Stevia) to others that are controversial, like Acesulfame K, Sucralose, and more.

Unfortunately, studies are scarce, and the conclusions are not clear here either – again, with some claiming that these are bad for you, while others are saying that they’re safe to drink.

It does seem that Stevia-sweetened drinks (that don’t have other potentially harmful chemicals like preservatives or other unhealthy sugar substitutes) are preferred and considered the safest of the bunch.

But make sure that it is only Stevia that these drinks have. On many occasions, diet drinks presented as “sweetened with stevia” also have other sweeteners included in the mix. So always read the list of ingredients to know exactly what you’re drinking!

Note: Did you know that I wrote a book about reversing fatty liver disease, based on my experience and all the research I did over the years? Read more about it here.

My approach

I personally stayed away from any soda for as long as I could during the initial dieting and exercising stages. For around six months, I only drank water, lemon water, coffee, and tea, and nothing else.

After six months, I started to drink (sparingly) freshly squeezed juices (usually orange and apple), mixed with plain water – although these aren’t safe either due to their high sugar content.

Around month 8 or 9, I started to drink diet sodas, but in moderation because I absolutely love my Coke and Pepsi. My plan is to limit intake to 1 can per week, but sometimes, usually during the summer, I drink one every 3-4 days.

Despite consuming these (including ones sweetened with aspartame), I still managed to reverse my fatty liver disease.

Does this mean that diet sodas are 100% healthy or at least not bad for your liver? Definitely not. But you know now what I personally did during this entire diet soda soap opera. Nobody is perfect, even though we’d like to be.

After stopping eating sugar and completely eliminating alcohol from my diet, I can only hope that this is the lesser evil I’m sticking with. However, I have to admit that after reading the latest findings on Aspartame, I am trying to switch to drinks that have none of it instead. That’s the very least I can do.

The Elephant in the Room

You’ve probably seen articles and even studies linking diet soda consumption with various health problems, including increased chances of developing MASLD.

But there is one thing that such studies fail to mention, usually: what is the current health status or at least weight of the participants, and how much exercise are they getting each day?

Most of the people that I know who drink diet sodas are already overweight and have always had weight-related problems, and some already have other health issues.

Since being overweight is the main risk factor for developing a fatty liver, it might not be the diet soda alone that causes it. It might have no influence whatsoever.

I mean, if you eat bacon and pizza and round it up with a big slice of cake, you don’t exercise at all, and you also drink diet soda, you can’t blame the latter for your fatty liver…

As I said above, it doesn’t mean that it’s safe to drink either, but it might not be as bad as some try to make it seem.

Is Coke Zero bad for your liver?

Out of all the sugar-free sodas out there, Coke Zero is the one that most people want to know more about. Mainly, is it bad for fatty liver or not?

Coke Zero has the controversial artificial sweeteners aspartame and Acesulfame K, preservatives (potassium benzoate), and caramel color, which some studies associate with metabolic issues when consumed in excess.

But, at the same time, all these “bad” ingredients for the liver are approved by the FDA and considered safe in moderation. So, at least in theory, Coke Zero is safe to drink even if you have MASLD/NAFLD. There’s no conclusive human evidence linking Coke Zero to liver damage or increased risks of developing liver-related problems.

I would still recommend choosing the less controversial options out there, with as few chemicals as possible – but I know from personal experience that there are no drinks that match the amazing taste of Coca-Cola or Pepsi (although I found one that’s really close – recommended below).

What are some safe-to-drink diet sodas for fatty liver?

I am writing this here at the bottom because I don’t want to encourage drinking any type of soda, no matter if they are diet or not.

I have to repeat that you’re better off ignoring them completely and drinking water, lemon water, tea, and coffee instead.

But if you really want to have one every now and then (and I insist on drinking them sparingly), the ones that I consider safer based on the ingredients are below (affiliate links, meaning that I get a small commission if you make a purchase following my links, but at no extra costs for you and without any influence on my side in regards of the actual recommendations):

• Bubly (sparkling water and natural flavors, no sweeteners)
• Spindrift Sparkling Water (sparkling water & fruit juice, no sweeteners – it still has sugar from fruits, but tiny amounts, between 1-4 grams per can)
• Green Cola (Coke/Pepsi alternative, sweetened with Stevia – this is becoming my new favorite)

These are the things that I personally consumed and still do. Sure, I do squeeze a flavored Diet Pepsi or a Zero Sugar Dr. Pepper more often than I’d like to because I love the taste, but for the most part I stick to the ones mentioned above when I want a treat.

And I still have them at a rate of one can per week (or at most every 3-4 days during the summer).

Final words

I don’t believe diet soda is the villain some make it out to be. I also don’t see it as harmless.

It’s the gray middle ground: probably safe when consumed on rare occasions, definitely risky when used as a water replacement (or consumed in excess). And most likely better than regular, sugar-sweetened soda.

If you are curious about other drinks – and whether you are allowed to have them or not, I wrote in the past about alcohol free wine and fatty liver, regular wine and fatty liver or beer and fatty liver.