Does an energy drink count as fasting?

December 1, 2025 •

4 min read

According to nutrition experts, any consumption of calories during a fast will technically break it. While most people understand that sugary energy drinks are forbidden, the rules around zero-calorie versions are less clear, leaving many to wonder: does an energy drink count as fasting?

Quick Summary

The consumption of most energy drinks, including zero-calorie versions with artificial sweeteners, can break a fast. Sugary drinks contain calories that disrupt the fasting state, while zero-calorie options can potentially trigger an insulin response, affecting metabolic benefits.

Key Points

Sugary energy drinks: Due to their high sugar and caloric content, regular energy drinks unequivocally break a fast.
Zero-calorie energy drinks: These can also disrupt a fast because artificial sweeteners may trigger an insulin response and increase cravings, even without calories.
Impact on insulin: A primary goal of fasting is lowering insulin; anything that causes a spike, including certain sweeteners, can hinder this benefit.
Fasting goals matter: For strict fasts (e.g., for autophagy), any non-water intake is avoided. For metabolic health, minimal calories or insulin response is the key consideration.
Best practice: The safest and most effective strategy is to consume only water, plain coffee, or unsweetened tea during your fasting window.

The Fundamental Rules of Fasting

At its core, fasting involves a period of voluntary abstinence from food and caloric beverages. The body, without a constant influx of energy from food, shifts its metabolic state to burn stored fat for fuel. However, the strictness of the fast depends on the individual's goals.

Fasting for Weight Loss vs. Autophagy

Weight Loss and Metabolic Health: For those primarily focused on losing weight or improving metabolic health, the goal is to keep insulin levels low. The consumption of carbohydrates and proteins can spike insulin, disrupting the fat-burning process. Some practitioners adhere to a looser rule, suggesting that fewer than 50 calories from certain sources may not significantly impact a fast.
Autophagy and Cellular Repair: Autophagy is the body's natural process of cleaning out damaged cells to generate new, healthier ones. This process is triggered by stricter fasting. For this benefit, any amount of calories, including the minimal ones in some low-calorie drinks, may interrupt the process.

The Impact of Regular Energy Drinks

Regular energy drinks contain substantial amounts of sugar and calories. For example, a 16 oz can of Monster Energy has 220 calories, while a Red Bull contains 160 calories.

Reasons a regular energy drink breaks a fast:

High Sugar Content: The high fructose corn syrup or sucrose in these drinks causes a rapid spike in blood sugar and a subsequent insulin response, immediately ending the fasted state.
Caloric Load: The sheer number of calories provides the body with instant fuel, halting the process of burning stored fat for energy.

The Problem with Zero-Calorie Energy Drinks

While zero-calorie energy drinks, such as Monster Ultra or Red Bull Sugarfree, seem like a safe bet, they can also interfere with a fast due to their artificial sweeteners and stimulants.

The Role of Artificial Sweeteners

Artificial sweeteners like aspartame, sucralose, and acesulfame potassium are commonly used in these products. While they contain no calories, they can potentially trick the body.

Insulin Response: Some studies suggest that the sweet taste of artificial sweeteners can trigger a cephalic-phase insulin response. Even if it's a small response, it can be enough to disrupt the benefits of a fast, especially for those with insulin resistance.
Increased Cravings: The sweet taste can also increase sugar cravings later, making it harder to stick to your fasting regimen and potentially leading to overeating during your eating window.

Other Ingredients and Effects

Stimulants: High doses of caffeine and other stimulants like taurine or guarana can raise cortisol levels, the body's primary stress hormone. Chronic elevation of cortisol can negatively impact blood sugar regulation and hinder weight loss efforts.
Acids: The citric acid in many energy drinks can be hard on an empty stomach, potentially causing GI upset, bloating, or heartburn.

Alternatives to Energy Drinks While Fasting

For those who need a morning or midday pick-me-up, safer alternatives exist that won't disrupt your fasting goals. Sticking to truly zero-calorie and un-sweetened beverages is the best approach.

Water: Plain still or sparkling water is the ultimate choice for hydration with zero calories and no effect on insulin.
Black Coffee: As long as it is consumed without milk, sugar, or cream, black coffee contains negligible calories and can even provide appetite-suppressing effects.
Unsweetened Tea: Unsweetened green, black, or herbal tea is a great option. Like coffee, it provides a minor caffeine boost without interfering with your metabolic state.
Electrolyte Water: Drinks with mineral salts can help with hydration, especially during longer fasts, without breaking it. However, always check the label for hidden sugars or fillers.

Regular vs. Zero-Calorie Energy Drinks While Fasting


Feature	Regular Energy Drink	Zero-Calorie Energy Drink
Calories	High (e.g., 220 in 16oz Monster)	Technically zero (under 5 calories per serving, as per FDA)
Sugar	High sugar content (e.g., 54g)	No sugar; uses artificial sweeteners
Fasting Impact	Immediately breaks a fast and spikes insulin due to high sugar.	Potential to break a fast by triggering an insulin response via artificial sweeteners.
Best for IF?	No, completely disrupts fasting benefits.	No, risks disrupting insulin and stimulating cravings.
Main Risks	Insulin spike, caloric intake, sugar cravings.	Potential insulin response, craving stimulation, gut health impact.

Conclusion

While the thought of a quick energy boost during a fast can be tempting, most energy drinks are incompatible with fasting. Sugary versions clearly break a fast due to their high caloric and sugar content, while zero-calorie versions contain artificial sweeteners that can cause a metabolic response and increase cravings. To ensure you maintain a truly fasted state and reap all the benefits, stick to simple, zero-calorie options like water, black coffee, or unsweetened tea. Your body will thank you for it, and you'll stay on track with your health goals.

Frequently Asked Questions

Yes, it can. While they contain no calories, the artificial sweeteners and additives in many zero-calorie energy drinks can still trigger an insulin response, which effectively breaks your fast for metabolic purposes.

In regular energy drinks, sugar and carbohydrates break a fast due to their caloric content. In zero-calorie versions, artificial sweeteners like sucralose or aspartame are the main culprits that can potentially cause an insulin response.

Technically, any amount of calories will break a fast. While some intermittent fasting practitioners adopt a 50-calorie rule for less strict methods, aiming for zero caloric intake is recommended for maximizing fasting benefits like fat burning and cellular repair.

Yes, black coffee and unsweetened tea are widely accepted during fasting because they contain negligible calories and generally do not cause an insulin spike. The caffeine may even help suppress appetite.

Fasting for weight loss focuses on staying in a low-insulin state to burn fat. Fasting for autophagy, a cellular repair process, requires a stricter approach, meaning any caloric intake is usually avoided, even minimal amounts.

The safest and most reliable drinks are plain water (still or sparkling), black coffee, and unsweetened teas. These options contain no calories and will not disrupt your body's metabolic state.

For most people, the amount of caffeine in black coffee or unsweetened tea does not significantly impact fasting benefits. In some individuals, high doses of caffeine might cause a small blood sugar increase, but this varies from person to person.