You can safely drink a handful of simple, low- or zero‑calorie beverages during intermittent fasting, as long as they don’t meaningfully provide energy (calories) or spike insulin.

Quick Scoop

1. Totally Safe Staples (Won’t Break Your Fast)

These are the go‑to drinks for most people who fast:

  • Plain water (still or sparkling): Naturally zero calories, keeps you hydrated and can help blunt hunger. You can add lemon slices or cucumber for light flavor as long as you’re not squeezing in lots of juice.
  • Unsweetened sparkling water : Same as water, just bubbly. Make sure the label has no sugar, no calories, and no sweeteners.
  • Black coffee : Coffee on its own has almost no calories and doesn’t significantly affect blood sugar or insulin for most people, so it’s widely considered fasting‑friendly.
  • Plain tea (hot or iced) : Black, green, oolong, herbal, and white teas, as long as you don’t add sugar, honey, milk, or cream. They provide antioxidants and can be calming or mildly energizing.

Think of the rule like this: if the drink has no calories (or truly negligible amounts), it almost never “breaks” a fast for fat‑loss and metabolic benefits.

2. “Okay in Moderation” Options

These can still fit into many fasting styles if you’re not ultra‑strict:

  • Very small splash of milk or cream in coffee/tea : A tablespoon of milk or cream adds a few calories. Some fasting approaches allow this because the overall calorie load is tiny, but stricter protocols avoid it.
  • Zero‑calorie sweeteners (stevia, some diet drinks) : Stevia drops in coffee or tea generally don’t add calories and often don’t affect blood sugar. Some people notice more cravings with sweeteners, and there’s debate about insulin responses, so if fat loss stalls, try cutting them.
  • Electrolyte drinks with no sugar : Sugar‑free electrolyte powders or tablets (sodium, potassium, magnesium) can help with headaches, fatigue, and muscle cramps while fasting—just make sure they are truly zero‑calorie.

3. Functional Drinks People Ask About

These drinks are popular in fasting discussions; whether they’re “allowed” depends on how strict you are and your goals.

  • Apple cider vinegar in water
    • ACV mixed with water (1–2 teaspoons in a glass) is low in calories and is often used for appetite control and blood sugar support.
* Most moderate fasting approaches consider this fine, but if you’re following a “water‑only” fast, you’d skip it. Always dilute to protect your teeth and stomach.
  • Infused and lemon water
    • Water infused with herbs, cucumber, or lemon slices usually doesn’t extract enough calories to matter, especially if you’re not eating the fruit.
* Squeezing half a lemon into water adds a few calories and a bit of vitamin C; for nearly everyone doing IF for weight and health, this will not meaningfully interfere with fasting benefits.
  • Bone broth
    • Bone broth contains protein, fat, and some calories, so technically it breaks a “pure” fast.
* Some people intentionally use it during longer fasts to get electrolytes and protein while still keeping calories much lower than a normal meal. It’s more like a “modified fast” tool.

4. Drinks That Usually Break a Fast

If your goal is fat loss, metabolic health, or autophagy, these are best saved for your eating window:

  • Any drink with sugar : Juice, soda (even “fresh” or “natural”), sweetened tea/coffee, energy drinks with sugar, sports drinks with carbs.
  • Milk, creamers, and flavored lattes : Regular milk, oat milk, almond milk lattes, flavored creamers, and “skinny” flavored drinks almost always carry enough calories to break a fast.
  • Protein shakes and collagen drinks : Protein and amino acids signal the body that “food has arrived,” so they end a fast.
  • Alcohol : Provides calories, affects blood sugar, and stresses the liver—definitely not fasting‑friendly.

5. How Strict Do You Need to Be?

There’s a lot of forum and social media debate around “what truly breaks a fast,” especially as intermittent fasting has become a big trend again over 2024–2026. Most people fall into one of three camps:

  1. Strict “water‑only” fasters
    • Only water (still or sparkling).
    • No coffee, tea, sweeteners, or functional drinks.
    • Often used for religious, medical, or deep autophagy‑focused fasts.
  1. Classic intermittent fasters (most common)
    • Water, black coffee, unsweetened tea as the default.
    • Many will allow zero‑calorie sweeteners, ACV in water, electrolytes, and lemon water.
 * Focus is on keeping calories essentially at zero during the fasting window.
  1. Flexible or “modified” fasters
    • Same as classic, plus occasional bone broth or small amounts of milk/cream for comfort or appetite control.
 * They accept that these technically break the fast but still see benefits because total daily calories and eating window are controlled.

If you’re using intermittent fasting mainly for weight loss and general metabolic health, what matters most is that your fasting drinks don’t meaningfully add calories or trigger big blood sugar/insulin spikes across the day.

Mini Checklist: Is This Drink OK?

Ask yourself:

  1. Does it have calories (check the label)?
  2. Does it contain sugar, honey, syrup, or juice?
  3. Is there protein or fat (milk, cream, collagen, MCT oil)?

If the answers are “zero or almost zero calories,” “no sugars,” and “no obvious protein or fat,” it’s usually compatible with intermittent fasting for most people.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.