What Can I Drink While Fasting? The Complete Allowed-Drinks List

What Can I Drink While Fasting?

While fasting, you can drink anything with essentially zero calories that won't spike your insulin: plain water, sparkling water, black coffee, plain tea (green, black, herbal), and no-calorie electrolyte drinks. What you must avoid is anything with calories, sugar, or sweeteners — that includes juice, milk, soda, sweetened coffee, bone broth (during a strict fast), and anything that makes your body think food has arrived. Stick to the "zero-calorie and unsweetened" rule and you'll stay firmly in the fasted state.

Why This Matters

The whole point of fasting is to keep insulin low so your body burns stored fat and runs autophagy. A single sweetened or caloric drink can spike insulin and quietly break your fast, undoing hours of benefit — even if the scale barely notices. Knowing exactly what's safe to drink lets you stay comfortable and hydrated without accidentally sabotaging your fast.

Drinks That Do NOT Break Your Fast

Water. The gold standard. Still or sparkling, plain water is always allowed and keeps you hydrated. Aim for steady intake throughout your fasting window.

Sparkling / carbonated water (plain). Fine, as long as it's unsweetened and unflavored with no added sugar or sweeteners. Naturally flavored ones with zero calories are usually okay, but check the label.

Black coffee. Plain black coffee has almost no calories and does not break a fast. It can even help suppress hunger and boost fat burning. Just no sugar, milk, cream, or syrups.

Plain tea. Green, black, white, oolong, and herbal teas are all excellent fasting drinks — zero calories, and some may support metabolism and reduce appetite. Drink them plain, hot or iced.

Electrolytes (no calories). For fasts longer than 24 hours especially, sodium, potassium, and magnesium prevent headaches, cramps, and fatigue. Use a sugar-free electrolyte mix or add a pinch of quality salt to your water.

Apple cider vinegar (small amount in water). A tablespoon of ACV in water has negligible calories and won't meaningfully break a fast; some use it to curb appetite. This is optional.

Drinks That DO Break Your Fast

Juice and smoothies. Full of sugar and calories — these break a fast instantly.

Milk and dairy (including in coffee). Even a splash of milk contains sugar (lactose) and protein that trigger insulin. Plant milks with added sugar do too.

Soda (regular). Loaded with sugar. Off-limits.

Sweetened coffee or tea. The moment you add sugar, honey, or syrup, your fast is broken.

Bone broth. Contains calories and protein. It's a great tool for breaking a fast gently, but during a strict fast it counts as food.

Alcohol. Contains calories and disrupts fat metabolism. Save it for your eating window.

The Grey Areas

Diet soda and artificial sweeteners. Technically zero-calorie, so they won't spike insulin much through calories. But some sweeteners may trigger a small insulin response or cravings in certain people, and diet soda isn't doing your health any favors. For a "clean" fast, skip them; for a looser "dirty" fast, they're tolerated by many.

Coffee with a tiny splash of cream. This is the classic "dirty fasting" habit. A small amount won't ruin fat loss for most people, but it does technically break a strict, autophagy-focused fast. If your goal is maximum autophagy, keep coffee black.

Flavored sparkling water. Usually fine if it's genuinely zero-calorie and unsweetened, but read labels — some contain sugar or sweeteners.

A Simple Rule to Remember

If it has calories or a sweet taste, assume it breaks your fast. If it's plain water, plain coffee, plain tea, or no-calorie electrolytes, you're safe. When in doubt, choose water.

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Frequently Asked Questions

Does coffee break a fast?

Plain black coffee does not break a fast — it has almost no calories and can actually help suppress appetite and support fat burning. Adding milk, cream, sugar, or syrup does break your fast, so keep it black.

Do electrolytes break a fast?

No-calorie, unsweetened electrolytes do not break a fast. In fact, on longer fasts they're recommended to replace sodium, potassium, and magnesium and prevent headaches and fatigue. Avoid electrolyte products with added sugar.

Can I drink lemon water while fasting?

A small squeeze of lemon in water has negligible calories and won't meaningfully break a fast. Just don't add sweeteners or drink lemon-ade, which is loaded with sugar.

Does tea break a fast?

Plain, unsweetened tea — green, black, herbal, or otherwise — does not break a fast and is one of the best fasting drinks. It only breaks your fast if you add milk, sugar, or honey.