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Is Diet Soda Keto Friendly?

Is Diet Soda Keto Friendly?

by Olivia Bradford -


It might seem that any food or drink with zero calories, sugar or carbs would be a shoo-in dietary staple on a ketogenic diet, but wait, there's more to consider. The team here at Konscious Keto wants to help you weigh out all the options.

The healthfulness, or lack thereof, of diet soda, on a ketogenic or any diet, extend beyond macronutrients.

Although drinking some of the diet sodas on the market may not impact your weight-loss efforts on keto, the artificial ingredients, coloring, and chemical additives may prove harmful to our  health.

If you're reading this, you've likely come over to—or are at least strongly considering—the side of thought that associates inflammation and disease with the excessive consumption of sugar.

We don't want to drink sugary beverages on a  ketogenic diet, but what are the consequences of drinking the sugar-free alternatives on the market?

And are there any sugar-free keto soda options that can help us achieve the best of both worlds, flavor and health-promoting or neutral benefits?

What is Diet Soda?

Simple answer, diet soda is a carbonated drink sweetened with something other than sugar and void of fat and calories.

Yes, this is true, but despite these drinks' neutral impact on weight or glucose spikes, there are other ingredients in these beverages that are directly linked to health issues.  

The following are the most concerning and commonly used ingredients in diet soda and why they're troublesome to our health:

Caramel Coloring

It sounds harmless enough and may subconsciously make you crave a candied apple, but this artificial element is far from natural or healthful—avoid it.

Caramel coloring is made by heating cane sugar or corn syrup to develop the desired color. And as you probably know, it's essential to make a concerted effort to avoid both corn syrup and cane sugar on a ketogenic diet as they both cause glucose spikes and release insulin in the blood which makes it virtually impossible to release fat.


This ingredient fell out of fashion more than a decade ago, even in mainstream health circles, so it's a bit surprising to see it still brandished on loads of nutrition labels of foods lining store shelves nationwide.

While a low-calorie sweetener was once ubiquitous to all foods on the low-fat bandwagon, aspartame's molecular composition and how it affects metabolic function is problematic.

Aspartame is comprised of three chemical compounds: phenylalanine, aspartic acid, and methanol. The first two are amino acids but the last, methanol, which is easily converted to 'free methanol' and then becomes toxic in large doses as it lastly turns to formaldehyde, is not advisable for human consumption.

Yes, that's formaldehyde: the stuff used to make building materials and many household products like plywood, fiberboard, glues, adhesives, permanent-press fabrics and paper product coatings—and this is significant because formaldehyde is a known carcinogen.

Some studies have directly linked the consumption of aspartame to the following disorders:

  • Depression
  • Anxiety
  • Weight gain
  • Diabetes
  • Fatigue
  • Epilepsy
  • Alzheimer’s disease
  • Parkinson’s disease
  • ADHD
  • Short-term memory loss
  • Multiple sclerosis
  • Fibromyalgia
  • Arthritis

So, while drinking diet soda may not expand your waistline, it may pose some more significant health risks long-term. Who knew diet soda intake could be so potentially damaging?

Does Diet Soda Fit Into a Ketogenic Diet?

So, we have at least established that there are diet sodas with ingredients that we should avoid, but aside from its health impact, you may wonder whether diet soda can fit into a ketogenic diet.


We cover the issue of foods that are keto-friendly per their macros but inadvisable because of their other potential health risks in our recently published article dedicated to which keto-friendly foods to avoid because they promote inflammation and increase the risk of disease, here.

We can use a similar perspective when answering whether diet soda can fit into a ketogenic dietary protocol. Diet soda can fit but whether we should drink it remains questionable at best.

On a macro level, we can easily fit diet soda into our keto program. After all, by their very nature, diet soda is zero-everything: no calories, fat, or sugar present to impact glucose or insulin.

But, consuming traditional forms of diet soda, usually sweetened with problematic options like aspartame, bring along with their sweet taste, a bitter pill to swallow on the backend due to increased inflammation and risk for disease when consumed over time.

Aside from the undeniable and inconvenient truth surrounding the safety, or lack thereof, of artificial sweeteners, you may be wondering if soda itself, carbonated water, flavoring, and a form of sweetener, in and of themselves are detrimental to our health.

We're glad you're thinking what we're thinking. We fortunately, have some sugar-free soda options on the market today—along with recipes to whip up homemade soda, thanks to recipe treasure-troves like Pinterest! So, we can keep it keto and still enjoy a little fizzy, fruit-flavored beverage throughout the week without the guilt. More on ideal soda alternative options on a ketogenic diet below.

Is Diet Soda Keto Friendly?

The encouraging news regarding the consumption of diet soda on keto is that, like many foods traditionally high in sugar or refined carbs, there are many ways to 'keto-fy' recipes. You can swap in healthier sugar replacements and other ingredients to ensure a given food or drink doesn't spike your blood sugar and disrupt the proper metabolic or hormonal function.  

We'll cover the most ideal beverages to consume on a ketogenic diet, especially if your goal is fat loss or to lean out. If you miss soda or need some for a low-carb-high-fat recipe like keto BBQ sauce, consider keto-friendly sodas like the line produced by Zevia—a soda line completely sweetened using stevia, which has a zero glucose effect.

While sugar-free, stevia-sweetened, soda is an excellent option for when you have a craving or when a recipe calls for soda, water remains the very best beverage option on keto—especially since the body releases more fluid, vitamins, and electrolytes when we drastically reduce carbs in our diet, as is the case with a ketogenic protocol.

Does Diet Coke Make You Fat?

Again, if we're looking only at macros, any diet soda, regardless of the sweetener used, as long as it allows one to maintain ketosis, would be permissible.

However, again and most importantly, the side effects of consuming artificial sweeteners like aspartame appear to counter and suppress some of the physiological benefits we seek and generally enjoy on a ketogenic diet like accelerated fat loss, mental sharpness, enhanced physical performance and stamina.

In addition to artificial sweeteners found in most diet sodas preventing weight loss and damaging the metabolism, they’re also known to contribute to an increased risk of conditions like:

  • Diabetes
  • Kidney damage
  • Depression
  • Cardiovascular disease
  • Cavities

Furthermore, the results of some recent studies indicate that drinking diet soda may be more harmful than drinking soda containing sugar! We know, it's wild!

What one recent study found in a comparative analysis between two participant groups, one who consumed regular, sugar-laden soda and the other that consumed diet soda with artificial sweeteners, may shock some.

The group that consumed diet soda evidenced increased symptoms of depression, by a whopping 30%, if consuming four or more cans of diet soda a day!

Furthermore, a recent study consisting of 263,925 people between the ages of 50 and 71, conducted in part by physician, Honglei Chen, MD, PhD, with the National Institutes of Health in Research Triangle Park in North Carolina and a member of the American Academy of Neurology, asserts a correlation between drinking diet soda that contains artificial sweeteners and an increase in and obesity, as compared to those who drank soda containing sugar.

Can Diet Soda Kick You Out of Ketosis?

Diet soda is capable of kicking us out of ketosis because diet sodas tend to contain sugar alcohols. Although it would take a very large amount of diet soda to do so, excessive consumption of diet soda can kick us out of ketosis.

However, the bigger issue is not whether we can drink diet soda but whether we should do so with the quality of our health in mind.

Forget getting kicked out of ketosis in this case: the long-term increased risk of cancer and heart disease associated with drinking diet soda are enough to make 'no' the short answer when pondering whether to drink diet soda on keto, or any other diet.

What Should You Drink on Keto?

Water, water, water!

We can enjoy collagen-rich bone broth, coffee, tea, and unsweetened seltzer water on a ketogenic diet without reservation about how they may impact our waistline or overall health. Water is the best beverage on keto or any other dietary program.

Our bodies need an increased amount of water due to the elevated levels of body fluid released on a ketogenic diet when we drastically remove carbs from our diet, as we've mentioned.

Plus, water is the original keto-friendly beverage: hydrating and free of all the keto ‘no-nos'.

Also, drinking water regularly helps facilitate gentle detoxification of the body—something that can only enhance the inherent beneficial side effects of eating a ketogenic diet, and who doesn’t love a little extra dietary leverage?

Keto-Friendly Juice Alternatives

Feel free to have a bit of fun with your water. You may be surprised by the array of options within the realm of keto that can keep your sipping time sublime and never boring.

Experiment with unsweetened, flavored, seltzer or a homemade lemonade sweetened with liquid stevia and seasoned with sprigs of mint for a refreshing, alkalizing and keto-friendly beverage that you can drink with confidence and without restriction.

Aside from drinking ample amounts of H2O, keto-friendly meal supplements are a favorable macronutrient option that can be used to break the fast gently—you know, instead of going in full-on for more substantial fare earlier in the day and jarring your digestive system.

Luckily, delicious, creamy, options like our Keto Shake take getting in our daily dietary needs and enjoying every strawberry-cheesecake-flavored sip to new heights.

Whether mixed with ice and blended to perfection plain, gussied up with a dollop of coconut butter or combined with fresh or frozen berries, Keto Shake is an excellent option to ensure you have a tasty and easy-to-pre-prep meal source to keep you nourished and hydrated throughout the day.


The discussion regarding the appropriateness of diet soda on a ketogenic diet in the context of it disrupting ketosis or stalling fat loss, broaches a broader and more important matter.

Above maintaining ketosis, the vital matter is whether drinking diet soda is healthy or will it cause an increased risk of multiple forms of disease thanks to its artificial sweeteners, colors, flavorings and fillers?

Again, the bigger issue is not whether we can drink diet soda but whether we should. We gravitate toward soda, diet soda, and fruit juice alternatives sweetened with stevia, monk fruit, or erythritol, as opposed to those concocted with the use of any artificial ingredients and advise you to do the same.

The ketogenic diet offers an endless list of benefits because of its ability to facilitate and support balance in the body, helping all systems run at their best, but diet sodas' ingredients can counter those benefits and act as dietary frenemies, silently derailing our weight-loss and wellness efforts with every sip.

Drinking a typical diet soda on a special occasion will not derail your efforts to remain in ketosis or lose weight.

However, for the benefit of overall health, consider experimenting with these soda alternatives to expand your repertoire while creating a metabolic state that enables you to enjoy the benefits of nutritional ketosis, unhindered by the potential metabolic damage posed by diet soda.



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Guo, X., Park, Y., Freedman, N. D., Sinha, R., Hollenbeck, A. R., Blair, A., & Chen, H. (2014). Sweetened Beverages, Coffee, and Tea and Depression Risk among Older US Adults. PLoS ONE, 9(4). doi:10.1371/journal.pone.0094715

Kmietowicz, Z. (2018). Type 2 diabetes: Sweetened drinks pose greater risk than other sugary foods. Bmj. doi:10.1136/bmj.k4943
Wersching, H., Gardener, H., & Sacco, R. L. (2017). Sugar-Sweetened and Artificially Sweetened Beverages about Stroke and Dementia. Stroke, 48(5), 1129-1131. doi:10.1161/strokeaha.117.017198

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