--- title: "What Can You Drink While Intermittent Fasting?" description: "Water, black coffee, and plain tea are fasting-safe. Milk, juice, and sweetened drinks break your fast. Here's the complete guide to drinks during a fast." source: https://easyfasting.net/blog/what-can-you-drink-while-fasting canonical: https://easyfasting.net/blog/what-can-you-drink-while-fasting published: 2026-06-16 updated: 2026-08-20 language: en publisher: EasyFasting (https://easyfasting.net) tags: intermittent-fasting, fasting-basics, what-breaks-a-fast, coffee-while-fasting citation: EasyFasting. "What Can You Drink While Intermittent Fasting?". https://easyfasting.net/blog/what-can-you-drink-while-fasting --- # What Can You Drink While Intermittent Fasting? ## Quick answer Safe: water, sparkling water, black coffee, and plain black, green or herbal tea, plus calorie-free electrolytes. Not safe: milk, juice, soft drinks, sweetened coffee, smoothies, alcohol and bone broth. Diet drinks are a grey area — no calories, but the sweet taste may trigger an insulin response in some people. One of the first questions people ask when starting intermittent fasting is: what can I actually drink during my fasting window? The answer matters — the wrong drink at the wrong time can break your fast; the right one makes the fasting hours significantly easier. The short version: **water, black coffee, and plain tea are all safe**. Almost everything else needs evaluation. This guide covers every common drink category, explains the science behind which ones break a fast and which don't, and gives you a quick-reference table you can use before reaching for anything during your fasting window. ## Why Some Drinks Break a Fast and Others Don't A fast is broken when you consume something that triggers an insulin response or delivers significant calories. Understanding [what fasting actually is](https://easyfasting.net/blog/what-is-fasting) — specifically the metabolic states your body cycles through — helps explain why some drinks are safe and others aren't. The two main mechanisms that break a fast: **1. Insulin response.** When insulin rises, fat oxidation stops. Your body switches back to glucose as its primary fuel. Anything that raises blood glucose (carbohydrates, some amino acids) or triggers insulin through other pathways (some artificial sweeteners via cephalic phase response) can pull you out of the fasted metabolic state. **2. Caloric intake.** The general threshold is around 50 calories, though the type of calories matters — carbohydrate and protein calories raise insulin more than fat calories. Keeping drinks under 5 calories per serving is the safest approach during a strict fast. For a comprehensive breakdown of what breaks a fast beyond drinks — including foods, supplements, and medications — see our [complete guide on what breaks a fast](https://easyfasting.net/blog/what-breaks-a-fast). ## What You Can Drink While Fasting: Quick Reference | Drink | Fasting-Safe? | Notes | |---|---|---| | Water (still) | ✅ Yes | Zero calories, zero insulin impact | | Sparkling water (plain) | ✅ Yes | Safe if zero calories and no sweeteners | | Black coffee | ✅ Yes | 2–5 kcal, no insulin spike | | Decaf coffee (black) | ✅ Yes | Same as regular — no insulin impact | | Green tea (plain) | ✅ Yes | Trace calories, may enhance fat oxidation | | Black tea (plain) | ✅ Yes | Trace calories, safe during fast | | Herbal tea (unsweetened) | ✅ Yes | Most varieties are fasting-safe | | Electrolyte supplements (zero-cal) | ✅ Yes | Sodium, potassium, magnesium — check for sugar | | Apple cider vinegar (diluted) | ✅ Generally | Trace calories, may improve insulin sensitivity | | Coffee with cream | ⚠️ Gray zone | ~50 cal/tbsp — may end autophagy for some | | Bulletproof coffee | ⚠️ Gray zone | Fat doesn't spike insulin but ends autophagy | | Diet soda | ⚠️ Gray zone | Artificial sweeteners may trigger cephalic insulin response | | Milk (any type) | ❌ No | Protein + carbs = insulin spike | | Oat milk | ❌ No | High in carbs | | Juice (fruit or vegetable) | ❌ No | Concentrated sugar | | Sports drinks | ❌ No | Sugar + carbs | | Sweetened coffee or tea | ❌ No | Sugar spikes insulin | | Protein shakes | ❌ No | Protein raises insulin significantly | | Alcohol | ❌ No | Calories + metabolic disruption | --- ## Water Water is the gold standard of fasting drinks. It has zero calories, zero insulin impact, and actively supports the fasting process in several ways: - **Reduces perceived hunger.** Mild dehydration is often misinterpreted as hunger. Drinking water when you feel a hunger pang during your fast frequently eliminates the sensation within 10–15 minutes. - **Supports kidney function** during fat metabolism — your kidneys process the byproducts of fat oxidation and need adequate water to function efficiently. - **Maintains electrolyte balance.** During a fast, kidneys excrete more sodium (lower insulin = less sodium retention). Drinking enough water — ideally with added electrolytes — prevents the "fasting headache" that many beginners experience. **How much:** aim for 2–3 liters (8–12 cups) of water per day during fasting. More if you exercise. ## Sparkling Water Plain sparkling water — carbonated water with no added flavors, sweeteners, or sugars — is completely fasting-safe. The carbonation has no effect on blood glucose or insulin. **Check the label carefully.** Many products sold as "sparkling water" or "sparkling mineral water" contain: - Added fruit juice (breaks fast) - Natural flavors that include sugars (may break fast) - Sweeteners like sucralose or stevia (gray zone — see below) Safe options: plain sparkling water (Perrier, San Pellegrino, unflavored LaCroix), or any product showing 0 calories and 0g carbohydrates on the nutrition label. ## Black Coffee Black coffee is the most widely used drink during intermittent fasting — for good reason. It's essentially calorie-free, doesn't trigger insulin, and actively supports fasting through multiple mechanisms. **What black coffee does during a fast:** - Enhances fat oxidation — caffeine increases fat mobilization from adipose tissue - Suppresses appetite — reduces ghrelin and blunts hunger signals - Improves cognitive function — helpful when energy dips during the early part of a fast - May support autophagy — coffee's polyphenols activate AMPK, the same pathway that drives cellular cleanup during fasting For the full science on black coffee and fasting — including the cortisol timing question and exactly what additives break your fast — see [Black Coffee While Fasting: Does It Break Your Fast?](https://easyfasting.net/blog/black-coffee-fasting). And for the comprehensive hub on all coffee + fasting questions, see [Can You Drink Coffee While Fasting? Here's the Truth](https://easyfasting.net/blog/coffee-while-fasting). **Timing tip:** wait 60–90 minutes after waking before your first cup. This lets the natural morning cortisol spike (cortisol awakening response) peak and begin declining before caffeine adds to it. ## Tea Plain tea — green, black, white, oolong, or herbal — is fasting-safe. The trace calories (2–5 kcal per cup) have no meaningful effect on insulin or fat metabolism. **Green tea** deserves special mention for fasting: - Contains **EGCG** (epigallocatechin gallate), a catechin that has been shown to enhance fat oxidation and modestly boost metabolic rate - Contains **L-theanine**, an amino acid that promotes calm focus and reduces the jitteriness that caffeine can cause — helpful during fasting hours when stress response may already be slightly elevated - Multiple studies have found that green tea catechins enhance the fat-burning effects of fasting **Herbal teas** (peppermint, chamomile, ginger, rooibos): all fasting-safe. Make sure they're unsweetened — most pre-packaged herbal teas contain no added sugar, but always check. **What to avoid with tea:** adding milk, cream, or sugar immediately breaks the fast (protein + carbs in milk, instant insulin spike from sugar). ## Electrolyte Drinks Electrolyte supplementation during fasting is often necessary, not just optional. Here's why: When insulin is low (as it is during fasting), your kidneys excrete more sodium. Sodium loss pulls magnesium and potassium with it. This depletion is responsible for most of the negative symptoms beginners associate with fasting: headaches, muscle cramps, fatigue, irritability, and brain fog. **What to look for in a fasting-safe electrolyte drink:** - Sodium: 300–500 mg per serving - Potassium: 100–300 mg per serving - Magnesium: 50–100 mg per serving - Sugar/carbohydrates: **0g** - Calories: **0 kcal** **What to avoid:** - Sports drinks (Gatorade, Powerade, Lucozade): contain 25–35g of sugar per serving — completely off-limits during a fast - "Healthy" electrolyte drinks with added coconut water or fruit juice: contain carbohydrates that break your fast - Electrolyte products sweetened with honey or cane sugar Safe options include LMNT (unflavored), Ultima Replenisher, Key Nutrients, or simply adding a pinch of sea salt to water. ## Apple Cider Vinegar A tablespoon of apple cider vinegar (ACV) diluted in water is generally considered fasting-safe. ACV contains: - Roughly 3–4 calories per tablespoon - Zero sugar, zero protein - Acetic acid, which research has shown to improve insulin sensitivity and slow gastric emptying Some intermittent fasting practitioners use ACV specifically to blunt post-fast insulin spikes by drinking it 15–30 minutes before their first meal. The evidence here is modest but directionally positive. **One caution:** undiluted ACV can damage tooth enamel and irritate the esophagus. Always dilute in at least 250ml of water. ## The Gray Zone: Artificial Sweeteners Diet soda and artificially sweetened drinks occupy the most contested territory in fasting science. The calorie count is effectively zero — but that doesn't mean they have zero metabolic effect. Some research suggests that artificial sweeteners (aspartame, sucralose, saccharin) can trigger a **cephalic phase insulin response** — essentially, your body releases a small amount of insulin in anticipation of calories, based on the taste of sweetness alone. This response varies by individual and by sweetener. The practical guidance: - **If your primary goal is weight loss**, diet sodas are unlikely to significantly impair your results - **If your goal is autophagy or strict insulin minimization**, avoid artificial sweeteners during your fasting window - **Stevia** has the least evidence of cephalic insulin response and is the safest sweetener choice for strict fasting ## What Definitely Breaks Your Fast To be clear about the other end of the spectrum: - **Milk, cream, oat milk, almond milk (with protein):** Protein triggers insulin; carbs in most plant milks raise blood glucose - **Juice (any kind):** Concentrated sugar, immediate blood glucose and insulin spike - **Smoothies:** Even "healthy" smoothies with fruit and yogurt contain significant protein and carbs - **Protein shakes:** Protein is the most potent insulin trigger after carbohydrates - **Sports drinks and energy drinks:** Sugar + carbs - **Alcohol:** Significant calories, and your liver prioritizes metabolizing alcohol over fat — it pulls you immediately out of fat-burning mode ## Building Your Fasting Drink Routine Here's a practical daily drink routine for someone doing 16:8 fasting (eating window: noon–8 PM): **7:00 AM (wake):** Water immediately — 500ml with a pinch of sea salt **8:00–8:30 AM:** First cup of black coffee or green tea (after cortisol peak begins declining) **10:00 AM:** Second cup of black coffee or herbal tea if needed **11:30 AM:** Zero-calorie electrolyte drink before breaking the fast at noon **12:00 PM:** Break the fast — now all drinks including milk, juice, etc. are permitted This routine covers hydration, electrolytes, caffeine, and hunger management across the entire fasting window without breaking the fast. --- Drinks are one of the most practical levers in intermittent fasting — the right choices make the fasting window easier; the wrong ones undo the work of the hours you've already put in. Keep it simple: water, black coffee, and plain tea during the fast, and hydrate aggressively to prevent the dehydration that most beginners mistake for hunger or fatigue. *EasyFasting is an iOS fasting timer that tracks your fasting phase in real time, shows which metabolic state you're in, and logs your streaks automatically. [Download it free on the App Store](https://apps.apple.com/app/id6764533304?pt=6764533304&ct=web_blog_cta&mt=8).* ## Frequently asked questions ### What can I drink while intermittent fasting? Water, sparkling water, black coffee, plain tea (green, black, herbal), and electrolyte drinks with zero calories are all safe during a fast. These drinks have negligible calories and don't trigger a meaningful insulin response, so they won't interrupt fat oxidation, ketone production, or autophagy. ### Does water break a fast? No. Water has zero calories and zero insulin impact. Drinking water freely during your fasting window is not only safe — it's recommended. Staying hydrated supports kidney function, reduces hunger signals, and helps maintain energy during the fast. ### Can I drink sparkling water while fasting? Yes. Plain sparkling water (no added flavors, sweeteners, or calories) is fasting-safe. The carbonation has no effect on blood glucose or insulin. Flavored sparkling water is fine as long as it contains zero calories and zero sweeteners. Check the label — many 'sparkling water' products contain added sugar or juice. ### Can I drink tea while intermittent fasting? Yes. Plain tea — green, black, white, oolong, or herbal — is fasting-safe. Tea has trace calories (2–5 kcal per cup) and no meaningful insulin response. Avoid adding milk, cream, or sugar during your fasting window. Many people find green tea particularly helpful during fasting because it contains L-theanine, which promotes calm focus without jitteriness. ### Do electrolyte drinks break a fast? It depends on the product. Zero-calorie electrolyte supplements (sodium, potassium, magnesium — no sugars or carbs) are fasting-safe. Sports drinks like Gatorade or Powerade contain significant sugar and will break your fast. Always check the label: if it has calories or carbohydrates, it breaks your fast. ### Can I drink diet soda while fasting? Technically no calories, but diet soda is a gray zone. Artificial sweeteners like aspartame and sucralose may trigger a cephalic phase insulin response (the anticipatory insulin release from the taste of sweetness) in some people. The evidence is mixed, but if your goal is strict insulin minimization, it's safer to stick to water, black coffee, or plain tea. --- About this document: this is the Markdown rendering of https://easyfasting.net/blog/what-can-you-drink-while-fasting, published by EasyFasting. Free to read and cite with attribution to EasyFasting (https://easyfasting.net).