Can You Drink Diet Soda While Fasting? Does Diet Soda Break a Fast?

Can You Drink Diet Soda While Fasting? Does Diet Soda Break a Fast?
Dr. Mario Ost

Dr. Mario Ost | Author

Dr. Mario Ost is a renowned nutrition scientist, researcher and lecturer, deeply invested in enhancing our basic understanding on mitochondrial fitness, muscle health, and endocrine organ crosstalk in sports, aging and metabolic diseases. He's a founder of a young athlete health academy and serves as a scientific advisor at Fastic, focusing on personalized nutrition concepts, fasting-mimicking food-components (autophagy-inducers) and benefits of exercise for metabolic homeostasis and healthy aging. As a devoted father and pioneer, Dr. Ost is shaping a future where elite athletes achieve peak performance and obese patients regain their metabolic and muscle health through an evidence-based approach on personalized training and nutrient timing.

You can drink diet soda during a fast if it’s low or zero calories and has no sugar. However, experts recommend avoiding diet soda during your fasting window because it can interfere with your fasting by increasing your appetite and sugar cravings. Other zero-calorie alternatives can help with intermittent fasting, especially if you’re doing it for weight loss. 

Can I Drink Diet Soda While Intermittent Fasting?

Most diet sodas contain very few or zero calories and have artificial sweeteners. Soda is technically permissible during intermittent fasting because there’s no sugar to spike an insulin response. Unlike a regular soda that contains sugar, diet soft drinks won’t bring you out of ketosis and break your fast. 

That said, it’s not entirely fast-friendly, and the culprit is the very sweeteners in it. Diet sodas have few or no calories because of artificial sweeteners like aspartame and sucralose. While these sweeteners don’t turn into glucose and activate insulin, they may cause problems in the long run. 

There’s strong research evidence that artificial sweeteners, such as sucralose and aspartame, may interfere with your oral and gut microbiome. Healthy gut microbiota helps with digestion and imbalances may lead to gastrointestinal conditions such as irritable bowel syndrome (IBS). 

Can Diet Coke Break a Fast?

Diet Coke may not break your fast as it has no calories. As it doesn’t contain any sugar, it won’t generate an insulin response and keep you in a fasted state. However, the artificial sweeteners used in Diet Coke may activate insulin in some people, as shown in one study with type 2 diabetes participants. 

If you have more questions like this about fasting, download the Fastic app. Its AI-powered chatbot can answer all your nutrition questions. It’ll help you make the right choices. 

The artificial sweeteners used in Coke are typically aspartame and Splenda, according to the manufacturer, the Coca-Cola Company. Although these sweeteners don’t have any calories, they’re not entirely safe for intermittent fasting because they can increase sugar cravings. 

If you’re fasting for weight loss, it may be a good idea to steer clear of Diet Coke or any other diet soda. You may be better off consuming it in your eating window, especially if you’re trying to lose weight. 

can you drink diet soda while fasting

Can Coke Zero Break a Fast?

Coke Zero is generally safe to consume during a fast. It has zero calories, which means no sugars to spike your insulin. But refrain from drinking too many of them. 

Also, some people may experience insulin activation, as their body mistakes the sweetness for sugar. Although rare, this effect can essentially bring you out of ketosis and break your fast. 

As mentioned earlier, Coke Zero and other diet soft drinks with artificial sweeteners may increase cravings. It's not the best when you’re trying to stay away from food!

Are Diet Sodas Bad for You?

The opinions and research on diet soda are pretty divided. The premise of sugar-free soft drinks like Diet Coke or Diet Dr. Pepper is that they contain no sugar, so they’re healthier alternatives to regular soda, which typically contains a lot of sugar. 

However, some experts and research argue that the artificial sweeteners used in diet soda are no good either, as they may increase sugar cravings and negatively impact your gut health. Some studies link artificial sweeteners to the risk of cancer, while others disprove it

Another potential issue with diet sodas is phosphorus. Zero-calorie soda contains phosphorus, and excessive consumption of this nutrient may increase the risk of cardiovascular disease. Processed and fast food are also high in phosphorus, so a diet dominated by such foods and soda will lead to a phosphorus intake higher than the recommended limit. 

Diet sodas are not harmful if used in moderation. Compared to regular sodas with copious amounts of sugar, carbonated drinks with artificial sweeteners are healthier. They won’t give you a lot of calories and won’t spike insulin in most people.

Particularly if you’re intermittent fasting for weight loss, diet soda is a better choice than regular soft drinks. You want to avoid sugar as much as possible to lose body fat. It’s best to track your food and calories, which is where the Fastic app comes in. It can help you keep tabs on what you eat and make adjustments as you progress in your intermittent fasting diet. 

Drink Diet Soda But With Caution

A diet soda won’t break a fast for most people. However, it may lead to increased feelings of hunger, especially for sugary stuff. It’s best to consume Diet Coke or other soda in moderation during fasting, and even better to drink it in your feeding window. 

Disclaimer: It’s advised to speak with a health professional before beginning intermittent fasting or a diet program. There may be side effects for people with certain medical conditions. 

With Fastic, millions of people have achieved their desired weight, overcome disease and regained their quality of life.

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