Yes, drinking plain water during a 16:8 fasting window is allowed and recommended for safe hydration.
During a 16:8 plan, your fasting window lasts sixteen hours with all meals packed into the remaining eight. Liquids with no calories, like water, fit the rules. The goal is a clean fast: fluids that don’t add energy or sweeteners, so your body stays in a fasting state while you stay refreshed and alert.
Drinking Water On A 16:8 Schedule: What Counts And What Doesn’t
Not every beverage is equal during a fasting stretch. Use the table below to see which drinks keep the fast, which ones are borderline, and which ones break it.
| Drink | Calories/Serving | Fasting-Friendly? |
|---|---|---|
| Plain water (still or sparkling) | 0 | Yes—ideal during the fasting window |
| Mineral water (unsweetened) | 0 | Yes—minerals don’t add energy |
| Black coffee | ~2 | Yes—skip milk, cream, sugar |
| Plain tea (green, black, herbal) | 0–2 | Yes—no honey or sweeteners |
| Electrolyte water (no sugar) | 0 | Often fine—choose unsweetened |
| Flavored seltzer (unsweetened) | 0 | Usually fine—watch for additives |
| Apple cider vinegar in water | ~0–3 | Borderline—tiny energy; keep minimal |
| Lemon slice in water | ~1 | Borderline—small effect; use sparingly |
| Diet soda | 0 | Technically zero energy; sweet taste may trigger hunger |
| Milk, creamers, or protein shakes | 50–200+ | No—breaks the fast |
| Juice or regular soda | 80–150+ | No—adds energy and sugar |
| Alcohol | 70–200+ | No—energy and dehydration risk |
Why Water Fits A Fasting Window
Plain water doesn’t supply energy, so it won’t end the fast. It aids daily functions like thinking, moving, and temperature control, and it helps curb snack urges that show up when thirst mimics hunger. Many people find that steady sipping makes a long stretch between meals feel steady.
Zero-energy tea and black coffee also help during the fasting block. Keep them plain to avoid sneaking energy into the window. If caffeine causes jitters or poor sleep, lean on water or decaf tea.
Hydration Targets During A 16:8 Routine
Your needs vary with body size, climate, and activity. A well-cited baseline comes from the U.S. National Academies: women average about 2.7 liters per day from drinks and foods, and men about 3.7 liters. That’s a daily total across the whole day. Meet much of it with water during the fast, then add water-rich foods and drinks with meals. For background on time-restricted patterns and allowed drinks, see Johns Hopkins overview and the National Academies water intake.
Practical Ways To Hit Your Fluids
- Start the morning with a tall glass before coffee.
- Keep a bottle nearby; sip every 30–45 minutes during the fast.
- Add a pinch of salt to one glass on sweaty days if your diet is low in sodium.
- Use plain sparkling water for variety if bubbles sit well with your stomach.
- Plan one bottle for each major task: commute, gym, or study.
Does Lemon Water Or Vinegar Break A Fast?
A splash of lemon or a teaspoon of apple cider vinegar adds trace energy. For most people, such tiny amounts don’t derail goals tied to time-restricted eating. If your plan is very strict, stick to plain water and plain tea. If sweet tastes nudge cravings, skip flavored options during the fasting block and keep flavors for the meal window.
Black Coffee, Tea, And Sweeteners
Black coffee and plain tea fit a clean fast. Non-nutritive sweeteners don’t add energy, yet they can nudge appetite in some people. If a packet of stevia or sucralose leads to snack urges, drop it. If it keeps you on track without cravings, an occasional packet is a personal call. Keep milk, cream, collagen, and medium-chain triglyceride oils for the eating block.
Electrolytes: When Plain Water Isn’t Enough
Hot days, long workouts, or GI illness can raise losses. In those cases, a no-sugar electrolyte tablet or mineral water can help during the fasting window. Read the label. If the product lists sugar or maltodextrin, save it for the eating block. When in doubt, plain water with a light pinch of salt and a squeeze of mineral-rich citrus during meals covers most daily needs.
Signs You Need Another Glass
Light yellow urine, steady energy, and moist lips point to good hydration. Darker urine, a dry mouth, or a dull headache suggest you’re behind. Sip water, then reassess in 15–20 minutes daily. Set timer cues if headaches tend to show up.
When Too Much Water Becomes A Problem
Chugging liters in a short span can dilute blood sodium. Early signs can be nausea, a throbbing headache, or confusion. Severe cases can bring vomiting or seizure. Spread intake across the day and match fluids to sweat and activity. If symptoms follow heavy intake, seek medical care.
Who Should Skip A Long Fasting Window
Some groups need tailored care. People with diabetes using insulin or sulfonylureas, a history of eating disorders, pregnancy or breastfeeding, or meds tied to meals need medical guidance first.
How To Pair Hydration With Meals
Use the eating block to rebuild electrolytes and fluids with water-rich foods and simple drinks. Think soups, yogurt, fruit, vegetables, and plain water at the table. That way the next fast begins from a better baseline. Salty meals pull in more water, so adjust your bottle plan.
A Simple Day Plan For 16:8
Here’s a sample layout many people find helpful. Shift the times to fit your schedule. The aim is steady fluids during the fasting block, then regular drinks with meals.
| Time Block | What To Drink | Notes |
|---|---|---|
| 06:30–09:00 (fasting) | Water; black coffee or plain tea if desired | One tall glass on waking; sip through the morning |
| 09:00–12:00 (fasting) | Water or unsweetened seltzer | Light, steady sipping; add a short walk if hunger spikes |
| 12:00–12:30 (first meal) | Water with food | Include fruit or soup for fluids |
| 13:00–16:00 (eating window) | Water; plain tea; no-sugar electrolyte tab if training | Split a bottle across this block |
| 16:00–20:00 (last meal ends) | Water with dinner; then taper | Aim to finish most fluids two hours before bed |
| 20:00–06:30 (fasting, sleep) | Sips only if thirsty | Nighttime bathroom trips drop with an early taper |
Common Questions On Water And A 16:8 Plan
Does Sparkling Water Count?
Yes, plain seltzer counts. Flavored seltzers with no sweeteners are generally fine, though some people notice bloating. If bubbles bother you, alternate with still water.
Will A Pinch Of Salt Break The Fast?
No. Sodium has no energy. A small pinch in one glass can help on hot days or after sweaty sessions.
What About Electrolyte Packets?
Pick products with no sugar for the fasting block. Save sweetened drinks or gels for long training inside the eating window.
Can I Drink During Workouts If The Workout Falls In The Fasting Window?
Yes. Water or no-sugar electrolytes are fair game. If a session is long or intense and you need energy, schedule it inside the eating window or plan a small pre-workout snack when your plan allows.
Hunger, Cravings, And What Water Can Do
Thirst often masquerades as hunger. Before you reach for a snack during the fasting block, drink a full glass and wait ten minutes. Often the urge fades. Cold water can give a brief alert bump, while warm water feels soothing during late afternoon lulls. If you feel lightheaded, sit, sip, and wait a few minutes. If symptoms keep coming back, shorten the fasting window and speak with a clinician who knows your history.
Smart Add-Ons During Meals
Think about the eight-hour block as your chance to set up the next fast. Add greens with a light dressing, a bowl of broth-based soup, fruit, yogurt, or a small baked potato with salt. These foods carry water and minerals that help you feel steady overnight and the next morning. Keep sweet drinks for treats inside the meal block, not during the fast.
Travel Days And Social Plans
Life won’t always match your ideal schedule. When travel or a late dinner throws things off, aim for two wins: keep fluids steady and avoid energy-bearing drinks during the fast. On flights, alternate plain water with plain tea. At a late event, sip seltzer with lime until the meal, then enjoy dinner and shift the next day’s window forward by an hour or two.
Morning Vs. Evening Fasts
Some people place the eight-hour block earlier, others later. Both setups can work. If late eating disturbs sleep or adds nighttime reflux, test an earlier window and move the last drink back by two hours. If training happens after work, a later window may feel easier since you can refuel soon after a session.
Method And Sources, In Brief
This guide draws on medical centers and nutrition authorities. For background on time-restricted patterns and allowed drinks, see guidance from Johns Hopkins Medicine and Cleveland Clinic. For daily fluid targets used across U.S. practice, see the National Academies Adequate Intake values. For overhydration risks, refer to a clinical overview on water intoxication from Cleveland Clinic.
Takeaway You Can Use Today
Yes to plain water during the fasting block. Keep coffee and tea plain, use unsweetened seltzer for variety, and space intake across the day. Use the meal window to refill with water-rich foods, simple drinks, and salt as needed. If you have a medical condition or use meds tied to meals, get personalized guidance before you start.