Coca-Cola Zero Sugar, or Coke Zero, aims to recreate the taste of the original Coca-Cola Classic without the sugar or calories.

It’s formulated to mimic the distinctive Classic Coke flavor — unlike Diet Coke, which has a unique flavor of its own.

If you follow the very low carb, high fat keto diet, you may wonder whether Coke Zero can be a part of your routine.

This article explores whether you should avoid Coke Zero on the keto diet.

The keto diet aims to flip your metabolism into ketosis, a metabolic state in which your body burns fat instead of carbs for energy.

This is achieved by maintaining a very low carb diet comprising 20–50 grams of carbs per day, as well as a high fat intake (1, 2, 3).

For context, one 12-ounce (355-mL) can of sugar-sweetened Coca-Cola Classic has 39 grams of carbs, whereas Coke Zero has none (4, 5).

Consuming too many carbs on the keto diet can take you out of ketosis and back into breaking down carbs for energy.


The high fat, very low carb keto diet aims to flip your metabolism into burning fat for fuel instead of carbs. To maintain ketosis, you typically cannot eat more than 20–50 grams of carbs daily.

Coke Zero provides zero calories or carbs (5).

Given that the goal of the keto diet is to keep your carb count low, typically between 20–50 grams per day, keeping track of your carb intake is crucial to staying in ketosis.

Coke Zero obtains its flavor from a combination of flavorings and artificial sweeteners. Artificial sweeteners are substituted for table sugar and aim to deliver sweetness to a food product.

Specifically, Coke Zero utilizes acesulfame potassium (Ace-K) and aspartame. While these don’t provide carbs or calories, they have been associated with negative health outcomes, such as an increased risk of diabetes and weight gain (5, 6).

Also, keep in mind that Coke Zero contains 34 mg of caffeine per 12-ounce (355-mL) serving — about 36% of the amount of caffeine found in a regular 8-ounce (240-mL) cup of coffee (5, 7).

While caffeine can give you an energy boost, it may dehydrate you if you consume it in large quantities. That’s because it’s a diuretic, meaning it stimulates your need to urinate.

However, you would need to consume more than 500 mg per day to see a dehydrating effect — that’s nearly fifteen 12-ounce (355-mL) cans of Coke Zero (8, 9, 10).

Do keep in mind that some people may be more sensitive to caffeine’s effects. Caffeine could trigger unwanted effects like anxiety, a racing heartbeat, or difficulties sleeping among those who are more sensitive to caffeine (11).

Furthermore, while it offers some sodium and potassium — 2% of the Daily Value for each — there are much more nutritious sources of these necessary minerals, which are vital for proper heart function, among many other crucial functions (12).

In addition, some studies have found that cola intake may increase your chances of developing osteoporosis.

This might be a concern for those on a keto diet, as getting enough vitamin D and calcium may be a bit more challenging when following this eating pattern. Both of these nutrients are important for osteoporosis prevention (13).

More research is needed to understand this relationship, particularly in the context of a keto diet.

Thus, while Coke Zero can occasionally provide variety as you quench your thirst on the keto diet, the optimal choice is water.

Other health considerations

While drinking soda, especially diet soda, is popular, it’s also controversial.

Frequently sipping on artificially sweetened soda is associated with adverse health effects, including kidney issues and the development of diabetes and metabolic syndrome (5, 14, 15, 16).

Metabolic syndrome is a cluster of symptoms associated with an increased risk of chronic disease.

Finally, those with the genetic condition phenylketonuria (PKU) should avoid Coke Zero, as it contains phenylalanine.

Phenylalanine is a common amino acid that’s harmful to those with PKU, as it can build up in the body and lead to serious complications, including irreversible brain damage and seizures (17, 18).

Finally, if you take medications for schizophrenia, you should also avoid Coke Zero, as phenylalanine can interact with them (19).


Coke Zero does not contain carbs or calories, which means it likely won’t knock you out of ketosis. However, given that frequently drinking diet soda is linked to adverse health effects, water is the best choice.

Coca-Cola Zero Sugar, or Coke Zero, recreates the Classic Coke flavor without any of the sugar or carbs.

It does so by substituting sugar with artificial sweeteners. This means you can drink it without knocking yourself out of ketosis.

However, the use of artificial sweeteners is controversial and linked to certain health risks. More research is needed in this area, especially in the context of a keto diet.

While Coke Zero may be an occasional treat to lend variety to your keto routine, water is always the optimal choice.