Does Diet Coke Break A Fast? [Full Answer, Backed By Science]
Does Diet Coke break a fast? Can you have diet coke while fasting? Get all of your questions answered here!

Does Diet Coke break a fast? Does diet soda break a fast? Can you drink Diet Coke while fasting?
Diet Coke doesn’t have any calories or sugar, so you may be wondering if you can drink it while fasting. Keep reading to get your answer!
Does Diet Coke Break A Fast?
Yes, Diet Coke will break your fast. Diet Coke contains artificial sweeteners that will trigger an insulin response and remove you from a fasted state.
Does Diet Coke Break A Fast – Further Details
Diet Coke has zero calories and zero sugar, so you may be surprised to read that Diet Coke will indeed break your fast. Let’s dive into why diet sodas break your fast.
Calories aren’t the only thing that can break your fast. Artificial ingredients and sweeteners can also break your fast.
Diet Coke contains artificial sweeteners. These sweeteners trigger an insulin response and break your fast.
Further, consuming artificial sweeteners in Diet Coke may increase cravings and your appetite. In turn, this can lead to weight gain as our bodies tend to crave sweets and higher-calorie foods after consuming diet sodas.
For more information on fasting, check out our ultimate intermittent fasting guide.
What Can I Consume While Fasting?
If you are following a clean fast, you can consume the following items when fasting:
- Water (unflavored, no added fruit)
- Black coffee
- Plain green tea or black tea
- Mineral water, unflavored sparkling water, seltzer water (with no added ingredients)
- Salt, electrolytes, or minerals (unflavored, no additives)
- Medications as prescribed by your doctor

Alternatives To Diet Coke While Fasting
If you are craving a Diet Coke while you are fasting, you might be looking for a fasting-safe alternative.
Our top recommendation is an unflavored sparkling water or seltzer water. Both will give you the carbonation and fizziness of a Diet Coke, but will not break your fast!
This unflavored sparkling water is made of 100% Sparkling Mountain Water.
Potential Side Effects And Risks Of Diet Soda
Diet Coke and diet sodas should be avoided while fasting. Additionally, I believe diet sodas should be avoided even when you are not fasting.
Here are some of the potential side effects and risks of consuming diet soda:
- Diet soda is associated with weight gain
- It can cause heart problems
- Diet soda may change your brain’s response to sweetness
- It can increase your risk of having a stroke
- Diet soda has been linked to type-2 diabetes
- It can disrupt gut health
- Diet soda can erode your tooth enamel
Additional Fasting Resources
- Does Diet Soda Break Your Fast?
- Do Energy Drinks Break A Fast?
- Does Zevia Break A Fast?
- Does Celsius Break A Fast?
Frequently Asked Questions
No, you should not drink Diet Coke while intermittent fasting. Diet Coke contains artificial sweeteners that will trigger an insulin response and break your fast.
No, you should not drink Coke Zero while fasting. Coke Zero contains artificial sweeteners that will trigger an insulin response and break your fast.
Yes, Diet Coke will break ketosis. Diet Coke contains artificial sweeteners that will spike your insulin levels, pull you out of a fasted state and therefore break ketosis.
During your fast, you should stick to water, coffee and tea. Avoid other zero calorie drinks while you are fasting as these drinks may spike your insulin levels and remove you from a fasted state.
Yes, drinking diet soda while fasting will stop autophagy. Diet sodas contain artificial sweeteners. These artificial sweeteners will break your fast and stop autophagy.