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Is Diet Coke Keto 2023: How Many Carbs & Diet Coke Side Effects

Heather Freudenthal

Updated on - Written by
Medically reviewed by Brittany Ferri, PhD

is diet coke keto

Many sodas have a high sugar content. That’s why so many people are able to lose weight after quitting soda. Diet sodas, such as Diet Coke, are sweetened with artificial sugars, aimed at people who want to enjoy the taste of soda without the calories. 

So, does diet soda make you fat? Scientific evidence has some mixed findings, but generally speaking, while diet sodas are keto-friendly, they may not necessarily lead to less weight gain compared to regular sodas. Diet Coke, specifically, is allowed on the keto diet since it has no calories, but does this make Diet Coke a healthy beverage choice for those doing keto? Not necessarily. A keto diet needs to be done responsibly. This  may require additional nutritional supplementation, such as the best multivitamin for keto. Let’s explore Diet Coke for keto further.

Is Diet Coke Keto: How Many Carbs Does Diet Coke Contains?

The hallmark of a ketogenic diet is high fat/low carb, which means people who follow the diet must not only eat a lot of fat, but also limit their carb and sugar intake to around 10% of their calories. Limiting carbs can be an effective weight loss strategy. Diet Coke has almost no carbs and no sugar (it is sweetened with artificial sugar), which makes the beverage acceptable for the keto diet. 

is diet coke keto
Diet Coke is low in carbs, making it keto-compliant.

Side Effects Of Diet Coke 

Bad For Gut Health

More and more evidence has surfaced which demonstrates that artificial sweeteners, such as the ones found in diet soda, cause disruption to the gut microbiome (the colony of bacteria in the digestive tract that is responsible for digestion, immunity, heart function, brain health, and autoimmune health). Repeated disruptions to our gut bacteria can lead to a host of health problems, including increased risk of metabolic syndrome[1] and glucose intolerance[2], not to mention stomach troubles such as diarrhea, constipation, gas, indigestion, bloating, and abdominal pain. 

Artificial Sweeteners Can Mimic Real Sugar

For all the advertising around artificial sugar being better than real sugar, the fact remains that artificial sugars can behave similarly in the body as real sugar, both leading to obesity[3], among other health issues. Scientists observed glucose profiles[4] over a 24-hour period and found not much difference in glucose patterns between people who consumed real sugar and people who consumed artificial sweeteners. 

Another way artificial sweeteners can mimic sugar is by stimulating the same neural pathways[5] in the brain that make us feel “rewarded” when we eat sugar. This is problematic because sugar leads to craving more sugar, and the same can be said about artificial sugar (consuming artificial sugar makes us crave sweets).

Associated With Cancer

Artificial sweeteners have been linked with several chronic and serious health conditions. Studies have shown that these artificial sweeteners, particularly aspartame and acesulfame-K (both used in diet soda), can increase the risk of developing cancer[6]. Artificial sugar can affect many different chemical reactions and mechanisms in the body, such as lowering our immunity and feeding unhealthy cells, that would increase the likelihood of cancer development.  

Can Lead To Mental Health Problems

is diet coke keto
Artificial sweeteners may have zero calories, but they drastically disturb the gut microbiome.

Around the world, mental health is declining, thanks in part to the fast food industry, with saturated fats, excess salt, processed foods, and sugar – including artificial sweeteners. Because these sweeteners can negatively alter our gut microbiome, our mood and cognitive health can be negatively impacted as well (many of our neurotransmitters like serotonin and dopamine are produced in the gut, along with melatonin). Artificial sweeteners, such as the ones found in Diet Coke, can increase the likelihood of experiencing migraines, erratic moods, anxiety[7], depression, headaches, and learning difficulties, among many other emotional impairments. 

Promotes Fat Storage

is diet coke keto
Artificial sweeteners in Diet Coke can cause the body to retain unwanted weight.

The idea behind artificial sweeteners is that, because they have zero sugar and zero calories, they will not add to weight gain. This might be true for some individuals. However, mounting evidence suggests that artificial sweeteners may have the opposite effect. When studied in both animals and humans, artificial sweeteners may lead to obesity[8] and metabolic syndrome. Not surprisingly, high consumption of diet soda can also lead to type 2 diabetes and increased sugar cravings (which can then lead to more caloric intake). 

Erodes Tooth Enamel

It’s common knowledge that sugar can “rot” teeth and give you cavities, but even sugar-free diet soda can be harmful for the teeth. Any soda, whether sweetened with sugar or aspartame is acidic, which can damage tooth enamel[9]. So if you’re hoping for a big, white smile, it’s helpful to cut back on diet soda, especially Diet Coke which is colored with caramel coloring, which can also stain the teeth.

Increases Risk Of Bone Fractures

Studies have shown that those who consume diet and regular soda have a higher risk of bone fractures[10] due to the phosphoric acid and caffeine in the soda. Bone loss can be serious, especially as we age, making it important to watch soda intake. Remember, weakened bones can not only lead to fractures, but also osteoporosis. 

Increases Risk Of Dementia And Stroke

Both sugar and artificial sweeteners have been studied for their influence in the development of dementia[11] and the likelihood of suffering a stroke. Scientific findings suggest that consuming one diet soda a day increases the risk of both stroke and Alzheimer’s disease threefold. Just as with other studies connecting sugar/artificial sweeteners to disease, researchers looked at both regular sugar and artificial sweeteners to see if one was more influential than the other, and found that they both have a part to play in deteriorating health. 

Other Side Effects From Caffeine

Aside from the dangers of artificial sweeteners, Diet Coke also contains caffeine. Caffeine is a stimulant naturally found in beverages like coffee and tea. While some people respond well to caffeine, for others it can cause headaches, rapid heart beat, nervousness, jitters, blood sugar imbalance, and adrenal overwork. If cutting back on caffeine is something you want to consider for your health, you’ll need to avoid Diet Coke and regular Coke, for that matter, and choose a non-caffeinated beverage instead.

Do Artificial Sweeteners Impact Ketosis?

Health implications aside, artificial sweeteners are considered okay to consume when looking strictly through the lens of the keto diet. These sugar substitutes do not affect blood sugar or ketosis (when the body burns fat for energy instead of carbohydrates) and contain no calories. 

That being said, drinking diet sodas which contain artificial sweeteners can impact ketosis in a few indirect ways. Because they mimic how sugar stimulates the brain, drinking sodas containing aspartame can make you crave more sugar, which can lead to excess snacking and binging. Additionally, when one consumes a no-calorie drink, it may give a false impression that it’s okay to eat higher calorie foods to compensate (for example, eating a hotdog and fries with a diet soda). These types of choices can add up to consuming excess calories and carbs, which can throw the body out of ketosis.

It’s important to stick to as many unprocessed, whole, chemical-free foods as possible while following the keto diet. Rather than eating “dirty” keto, in which you’re only focused on reducing calories from carbs, it’s best to consider the quality of the food and make sure all ingredients support your well-being.

What To Drink On A Keto Diet Rather Than Diet Coke 

It’s clear that Diet Coke, or any diet soda, can have serious health consequences when consumed regularly. However, being on a keto diet is already restrictive and it may be challenging to give up your favorite drinks. Luckily, healthier alternatives are available that are both good for the body and compliant with the keto diet. They include:

  • Green Tea
  • Mineral Water
  • Seltzer or Sparkling Water
  • Bulletproof Coffee
  • Unsweetened Nut Milk (e.g., almond milk)
  • Smoothie (minimal fruit)
  • Diluted Fruit Juice (a little fruit juice mixed with water to reduce the sugar content)
  • Veggie/Green Juice

Beverages That Are Not Keto-friendly 

It’s important to keep sugar to a minimum when following the keto diet. When it comes to beverages, you’ll want to avoid any sweetened drinks, as well as any milks that come from grains. Drinks that are not allowed on the keto diet are:

  • Oat Milk
  • Rice Milk
  • Energy and Sports Drinks
  • Sodas
  • Fruit Juice


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Diet Coke is a traditional soft drink consumed all over the world. It contains no real sugar, and instead, artificial sweeteners to give it its classic sweet taste. While these sugar replacements make the beverage keto-friendly, they pose serious health concerns, from gut disruption, to cognitive impairment, obesity and cancer. For those looking to follow a keto diet and want to drink soda, Diet Coke is a suitable choice, but should be consumed in moderation (as a treat, rather than daily). 

+ 11 sources

Health Canal avoids using tertiary references. We have strict sourcing guidelines and rely on peer-reviewed studies, academic researches from medical associations and institutions. To ensure the accuracy of articles in Health Canal, you can read more about the editorial process here

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Heather Freudenthal

Medically reviewed by:

Brittany Ferri

Integrative Nutrition Health Coach and Wellness Writer with a holistic and functional medicine/root cause mindset. My writing style is engaging, relatable, and educational, designed to help readers digest and relate to complex topics in nutrition, gut health, hormone health, mental health, and spiritual health, then inspire them to take action.

Medically reviewed by:

Brittany Ferri

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