Can I drink Sprite during fasting? A look at how sugar and sweeteners affect your fast

October 18, 2025 •

4 min read

Research from Johns Hopkins neuroscientist Mark Mattson notes that the body shifts from burning glucose to burning fat after a period without food. This metabolic switch is a cornerstone of fasting, leading many to question if a seemingly innocuous drink like Sprite, or its zero-calorie version, is compatible. So, Can I drink Sprite during fasting? The answer is more complex than a simple yes or no.

Quick Summary

Regular Sprite's high sugar content immediately breaks a fast. While Sprite Zero is calorie-free, its artificial sweeteners may trigger an insulin response, potentially negating fasting benefits.

Key Points

Regular Sprite is not fasting-friendly: With over 140 calories from sugar, it immediately breaks a fast and triggers an insulin spike, halting fat burning and autophagy.
Sprite Zero is debatable: Although calorie-free, its artificial sweeteners can potentially trigger an insulin response and increase cravings in some people, depending on individual metabolism and goals.
Artificial sweeteners have potential metabolic effects: Studies suggest that the sweet taste can confuse the body, potentially leading to insulin release and affecting gut health, even without calories.
Strict fasting avoids all sweeteners: For those fasting for maximum autophagy and metabolic benefits, the safest bet is to avoid all artificially sweetened beverages during the fasting window.
Water and other unsweetened beverages are the safest options: Plain or sparkling water, black coffee, and unsweetened teas are the best choices to maintain a fasted state and ensure full benefits.

The Basics of Fasting and Its Metabolic Goals

Fasting is an eating pattern that restricts food intake for set periods, triggering beneficial metabolic changes in the body. For most fasters, the primary goals include weight loss, improved insulin sensitivity, and inducing a process called autophagy, or cellular cleansing. The fundamental principle is to keep caloric intake low enough during the fasting window to maintain a fasted metabolic state. Most experts define this as consuming fewer than 50 calories.

During a fast, the body depletes its sugar (glucose) reserves and switches to burning stored fat for energy in a process known as ketosis. Consuming any significant amount of carbohydrates or sugar will cause an insulin spike, immediately halting this process and pulling the body out of its fat-burning state.

The Impact of Regular Sprite on a Fast

Regular Sprite is a carbonated soft drink that contains a high concentration of sugar, specifically high-fructose corn syrup. A typical 12-ounce can of Sprite contains over 140 calories, all derived from its sugar content. This makes it unambiguously incompatible with any form of fasting.

Here’s a breakdown of why regular Sprite breaks a fast:

High Caloric Load: With over 140 calories per can, regular Sprite provides a significant energy source that triggers a full metabolic response, shutting down the benefits of fasting.
Blood Sugar Spike: The sugar is rapidly absorbed into the bloodstream, causing a sharp rise in blood glucose levels. This, in turn, prompts the pancreas to release insulin.
Halts Ketosis and Autophagy: The release of insulin inhibits fat oxidation (fat burning) and also shuts down the cellular repair process of autophagy. These are two of the most sought-after benefits of fasting.

The Controversy: Can I Drink Sprite Zero During Fasting?

Sprite Zero, marketed as a zero-calorie, zero-sugar alternative, presents a more nuanced dilemma. It contains artificial sweeteners like aspartame and acesulfame potassium instead of sugar. From a strict caloric perspective, since Sprite Zero contains zero calories, it does not provide the energy that would typically break a fast. However, the debate hinges on the physiological and psychological effects of the artificial sweeteners.

Experts present several reasons why even diet sodas might be problematic during fasting:

Potential Insulin Response: Some studies and experts suggest that the sweet taste of artificial sweeteners can trick the body into releasing insulin in anticipation of sugar. While this effect varies among individuals, for someone whose primary goal is insulin regulation, this could be a concern.
Increased Cravings: For many, the taste of sweetness, even from non-caloric sources, can increase cravings for sugary foods, making it harder to stick to the fast. This can undermine the psychological benefits of controlling your palate.
Impact on Gut Microbiome: Research suggests that artificial sweeteners may negatively affect the gut microbiome, which can have downstream effects on metabolic health. A healthy gut is often a target for those practicing fasting for overall health.

A Comparison of Fasting Beverages

This table illustrates the different effects common beverages have during a fasting window, from the most disruptive to the most fasting-friendly.


Feature	Regular Sprite	Sprite Zero	Water (Still/Sparkling)
Calories	High (~140 per can)	Zero	Zero
Sugar	High	Zero	Zero
Fasting State	Immediately Breaks	Potentially Disrupts	Preserves
Insulin Response	Strong Spike	Possible, Varies by Person	None
Autophagy	Halts	Potential for Disruption	Promotes
Best for Fasting?	No	Debatable / Use Caution	Yes

Healthier Alternatives to Sprite While Fasting

For those seeking a refreshing, non-caloric beverage during their fast, there are numerous options that won't compromise your health goals. These alternatives provide hydration and, in some cases, additional benefits without the potential pitfalls of artificial sweeteners.

Plain Water: The gold standard for hydration. Drink still or sparkling water to stay hydrated and energized during your fast.
Black Coffee: An excellent tool for fasting, black coffee contains minimal calories and may help suppress appetite and boost fat oxidation due to its caffeine content.
Unsweetened Tea: Herbal teas like peppermint or chamomile, and traditional teas like green or black tea, are great options. They offer a variety of flavors and provide antioxidants without added calories or sugar.
Water with Lemon or Lime: Adding a squeeze of fresh lemon or lime to your water can provide a refreshing flavor boost with minimal calories (usually less than 5), which is generally acceptable for most fasting protocols.
Diluted Apple Cider Vinegar: Mixing 1-2 teaspoons of apple cider vinegar with water is thought to help with blood sugar regulation and curb cravings, making it a popular choice for some fasters.

Conclusion: Making the Right Choice for Your Fasting Goals

The question, Can I drink Sprite during fasting?, has a clear answer for its regular version and a more complex one for the zero-calorie alternative. Regular Sprite's high sugar content is an immediate deal-breaker, triggering a metabolic response that ends the fasted state and negates key health benefits. While Sprite Zero contains no calories, the artificial sweeteners can be problematic for some individuals by potentially causing an insulin response, increasing cravings, and disrupting the gut microbiome.

Ultimately, the best approach is to stick to the safest and most effective beverages for fasting: plain water, black coffee, or unsweetened tea. These options will provide hydration and potential health boosts without any risk of interfering with the metabolic goals of your fast. If you must have a fizzy drink, a plain sparkling water with a hint of lemon or lime essence is a far better choice. Your specific fasting goals—whether for weight loss, autophagy, or metabolic health—should guide your decision. Always consult a healthcare professional for personalized advice on your fasting regimen. For more information on the science of fasting, visit the Johns Hopkins website.

Frequently Asked Questions

While Sprite Zero is technically calorie-free and won't break a fast from a caloric standpoint, its artificial sweeteners can trigger an insulin response in some people, which could potentially disrupt your fast for other metabolic purposes like autophagy.

The sweet taste of artificial sweeteners can sometimes 'trick' your body into thinking sugar is coming, which may trigger an anticipatory insulin release. This insulin can inhibit the fat-burning process and interfere with other fasting benefits.

The best drinks for fasting are plain water (still or sparkling), black coffee, and unsweetened tea. These contain zero calories and no additives that would disrupt the fasted state.

While a few calories (e.g., under 50) might be acceptable for some fasters focused solely on calorie restriction, it technically ends a strict fast. For benefits like autophagy, zero caloric intake is ideal. The source of calories also matters.

Drinking a regular Sprite will break your fast due to its sugar and calorie content. You will experience a blood sugar spike, and your body will exit its fat-burning state. The best course of action is to resume your fasting protocol and be mindful in the future.

Yes, you can have carbonated drinks, but they should be plain or flavored with natural essences and contain no sugar, calories, or artificial sweeteners. Plain sparkling water is a great alternative to soda.

For many, the sweet taste of diet soda can increase cravings for other sugary foods, making the fasting period more difficult to manage psychologically. This can undermine your weight loss or health goals.