16:8 Fasting Schedule: Example Eating Windows That Fit

A 16:8 fasting schedule means you eat during an 8-hour window and don't eat for the other 16 hours. The 16 hours start when you finish your last bite of the day and end when you eat again, so a 12 pm to 8 pm eating window means your last food is around 8 pm and your next is around noon the next day.

You can slide that 8-hour window anywhere that suits your life. This guide gives example windows, shows how to count the hours, and lays out a one-week ramp so you don't jump straight from three meals and a late snack to a 16-hour gap. If you'd rather see your own window drawn out, the fasting schedule calculator does it from your wake-up and sleep times.

This is general information, not medical advice. Talk to a doctor before fasting if you have a medical condition (such as diabetes), take medication, are pregnant or breastfeeding, are under 18, or have ever had an eating disorder. Stop and get help if you feel unwell.

What 16:8 means (and what it doesn't)

The first number is your fasting hours. The second is your eating hours. Together they make 24. During the fasting hours you have water and other drinks without calories. During the eating hours you eat as you normally would, in one, two, three or more meals.

Researchers often call this pattern time-restricted eating, and some reserve "intermittent fasting" for plans with whole days of fasting. Harvard Health describes 16/8 as one of the more popular approaches, with an example of eating from noon to 8 p.m., and says the long-term benefits are not yet known. People online use the two terms interchangeably, and so does this guide.

Two things 16:8 does not do on its own. It does not tell you what to eat, and it does not guarantee any result. Research is mixed. A 12-week randomized trial of 16:8 in adults with overweight or obesity, published in JAMA Internal Medicine, found weight change that was not significantly different from the group that ate three structured meals a day. A review in the New England Journal of Medicine covers the wider research on fasting patterns and is a good read if you want the science rather than the hype. Some people find a window simply makes eating decisions easier. Others find it makes no difference, and that's a fine thing to learn.

When do the 16 hours start?

This is the question people ask most when they begin. People often wonder whether the clock starts at the last meal, at bedtime, or when they stop feeling full. The simple answer is the last meal.

The fast starts after your last food or caloric drink. If dinner ends at 7:30 pm, your 16 hours run until 11:30 am. Going to bed does not start the clock, and neither does your stomach feeling empty.

A few details that save arguments with yourself:

• A small late snack moves the start. If you finish dinner at 7:30 but have a handful of nuts at 9:30, your 16 hours now begin at 9:30 and end at 1:30 pm. Many people say their "16 hours" quietly turns into 13 or 14 for exactly this reason, and a few threads in r/intermittentfasting make the point that real 16-hour fasts are rarer than people claim.
• Count to the first bite, not to waking up. Sleep counts toward your fasting hours, but your fast ends when you eat, not when you open your eyes.
• Use a timer, not memory. Writing down the time of the last bite sounds fussy, but it removes the guessing. The When can I eat? timer takes the time your last meal ended and shows when your window opens.

Example 16:8 eating windows

Here are the windows people use most. None is better for everyone. Pick the one that matches when you are hungry and when you have to be around other people.

Eating window	Last food of the day	First food next day	Good fit if
12 pm to 8 pm	8 pm	12 pm	You skip breakfast anyway and eat dinner late
11 am to 7 pm	7 pm	11 am	You want an earlier lunch and a 7 pm dinner
10 am to 6 pm	6 pm	10 am	You like an early dinner and a late breakfast
9 am to 5 pm	5 pm	9 am	You want to be done eating well before bed
8 am to 4 pm	4 pm	8 am	You are up early and fine with a very early dinner

Is 12 to 8 or 10 to 6 better?

Neither is proven better. A 12 to 8 window suits people who dislike breakfast and want dinner with family. A 10 to 6 window suits people who get hungry in the morning and want a longer gap before bed. Some research looks at eating earlier in the day, but the evidence is not strong enough to say there is one correct window for everyone. The practical test is which window you can keep up for weeks, not which sounds best.

Example day on a 12 to 8 window

• Morning: Water, black coffee or plain tea.
• 12 pm: First meal.
• 3 pm: Snack if you want one.
• 6:30 pm: Dinner.
• 8 pm: Window closes. Water or herbal tea after this.

Example day on a 10 to 6 window

• 7 am: Water, plain coffee or tea.
• 10 am: First meal.
• 2 pm: Second meal.
• 5:30 pm: Dinner, finished by 6.
• Evening: Herbal tea or water.

A 7-day ramp from 12:12 to 14:10 to 16:8

Jumping straight to 16 hours is the most common reason people quit in week one. Hunger, a headache and a short temper are all common reports from people who start too hard. A slower ramp costs you a week and tends to go better.

1. Days 1 and 2: 12:12. Finish dinner at 8 pm, eat again at 8 am. For many people this is already close to what they do. The goal is to stop eating after dinner.
2. Days 3 and 4: 14:10. Finish at 8 pm, eat at 10 am. Notice which hour of the morning is hardest.
3. Days 5 to 7: 16:8. Finish at 8 pm, eat at noon, or shift the whole window earlier if evenings are hard.
4. Week 2 onward: Keep the window you can actually repeat. If 16:8 feels bad, stay at 14:10 for another week. There is no prize for speed.

Fastly has 12:12, 14:10 and 16:8 as built-in presets, so you can switch plans without doing any math.

What can I have during the fast?

Most guides agree on water. Plain tea and black coffee are common too, and the details are where people argue.

• Water, sparkling water: Fine.
• Black coffee and plain tea: Commonly allowed because they have almost no calories. Some people avoid them to protect sleep or because caffeine on an empty stomach makes them jittery.
• Milk, cream, sugar, syrups: These add calories, so most people treat them as breaking the fast. A splash of milk is a gray area people debate. If you want a clean 16 hours, skip it.
• Zero-calorie drinks and flavored water: People disagree on whether sweeteners make hunger worse. Try it and see how you feel.
• Supplements and vitamins: Many are fine, but some are best with food and can upset an empty stomach. Ask a pharmacist or doctor about yours.

"Does it break the fast?" has no single official answer. A fast in the strict sense means no calories, and anything beyond that depends on what you are fasting for. If you are doing this for convenience, a splash of milk in coffee probably does not matter much. If you want a firm rule, use calories as the line.

If you take medication, ask your doctor whether it needs food and when. Do not skip a medication to keep a fast going.

What if I ate at 9 pm and want to start at 11 am?

That is a 14-hour fast, and it is a perfectly good place to begin. If you want to hit 16 hours after a 9 pm meal, your first food would be 1 pm. You have three honest choices: eat at 11 and call it 14:10, push breakfast to 1 pm, or finish dinner earlier tomorrow. Choosing the first is not failing. It is what the ramp above is for.

How to handle a social dinner

People ask this all the time, and the answer is that the schedule serves your life, not the other way around. A few options:

• Move the window that day. If dinner is at 8:30, make the window 12:30 to 8:30 or 1 to 9. The hours still add up to 16 and 8.
• Eat earlier and keep dinner small. Have a bigger lunch and a lighter plate at dinner.
• Skip the fast for one night. One flexible day does not undo the rest of the week. You can start again the next morning.
• Pick a plan with slack. If your evenings are packed, 14:10 might fit better than 16:8.

When does it get easier?

Many people report that the first week or two is the hardest, with hunger around your usual meal times. That hunger tends to come in waves and often passes if you wait it out with water or tea. Others find it takes longer, and a few never settle in. If you feel dizzy, weak, shaky or unwell, stop and eat. That is not a test of willpower. The Mayo Clinic lists tiredness, dizziness, headaches and mood swings as possible effects, and says people with diabetes or other medical conditions should talk with their health care team before starting.

Things that often help:

• Eat real meals in your window, with protein and fiber, so you aren't constantly hungry at hour 14.
• Drink water through the morning.
• Keep your window consistent for a week before changing it.
• Go to bed at a regular time. Poor sleep makes hunger louder.

16:8 or 18:6?

Several r/intermittentfasting threads ask whether to move from 16:8 to 18:6. There's no rule that longer is better. A longer fast is harder to keep up and leaves less time to eat enough, and a pattern you drop after two weeks does nothing. A reasonable approach is to stay at 16:8 until it feels easy for a month or so, then decide if you want to try more. The OMAD vs 20:4 vs 18:6 guide compares the longer plans.

What if I miss the window one day?

Nothing happens that needs fixing. You ate at 10 am instead of noon, or had a late snack. Note it, and start your next fast after your next meal. Treating one slip as a reason to quit is what ends most attempts, more than the slip itself.

When 16:8 may not be for you

16:8 is not a good fit for everyone. Skip it, or get medical advice first, if any of these apply:

• You have diabetes or take medication that affects blood sugar.
• You are pregnant or breastfeeding.
• You are under 18.
• You have ever had an eating disorder, or counting hours and restricting food stresses you out.
• You are very active and struggle to fuel your training in an 8-hour window.

Fasting is a pattern you can drop at any time. If it makes you anxious, preoccupied with food or physically unwell, that is a good reason to stop.

If your schedule doesn't match the clock

Shift workers, parents of newborns and anyone with changing hours do better anchoring the window to their own day than to the clock. Pick the time you wake up, then place the 8-hour window where it fits. The fasting schedule calculator takes wake-up and sleep times and handles windows that wrap past midnight. The night shift guide goes through this in detail.

Using Fastly for your 16:8 schedule

This site is made by the makers of Fastly, a fasting timer for iPhone and Android. Here is what it does, and only that:

• One-tap timer. Tap Start Fast and a progress ring counts your time. If you forgot to start it when you finished dinner, you can edit the start time.
• A 16:8 preset. Plans include 12:12, 14:10, 16:8, 18:6, 20:4 and OMAD (23:1), plus a custom goal in hours.
• Notifications and a widget. A notification when your fast is complete, milestone alerts along the way, and a home screen widget.
• Streak and weekly activity. A streak card, weekly chart and fasting stats so you can see how consistent you have been.
• Weight and water logs. Log your weight against a goal and a daily water target, with charts. See the guide on when the scale won't move for how to read them.
• No account. Your data is stored on your phone, and the timer works offline.
• Fasting stages. A card shows the stage people commonly describe for each hour. It is educational and not a measure of your body.

What it doesn't do: it doesn't give medical advice, it doesn't tell you what to eat, and it doesn't promise weight loss or any health result. Fastly is free to download, and some features, such as your full fasting history and CSV export, need Fastly Pro. If you just want a timer and don't want an app, the When can I eat? timer works in your browser, and the best free fasting apps guide explains what to check before you install anything. You can also see all of it on the Fastly home page.

Questions

Does the 16 hours start at my last meal or at bedtime?

At your last meal or caloric drink. Bedtime doesn't start the clock. If your last bite is at 8 pm, 16 hours later is noon.

Can I have coffee in the morning?

Plain black coffee and unsweetened tea are commonly used during a fast because they have almost no calories. Milk, cream and sugar add calories, so most people count them as ending the fast. Caffeine on an empty stomach bothers some people, so notice how you feel.

Do most people's 16 hours really last 16 hours?

Often not. People say snacks and sips of calorie drinks near bedtime or first thing shorten the gap, so a "16-hour" fast is closer to 13 or 14. Writing down your last bite or using a timer shows you what you actually do.

I ate at 9 pm. Should I still start at 11 am?

You can, but that is a 14-hour fast. If you want a full 16, your first food would be at 1 pm. Either is fine, and 14:10 is a useful place to start.

How do I handle a dinner out on 16:8?

Move your window later that day, eat a bigger lunch and a lighter dinner, or take the night off and begin again tomorrow. One flexible day doesn't ruin the week.

Is 16:8 safe for everyone?

No. Talk to a doctor first if you have a medical condition such as diabetes, take medication, are pregnant or breastfeeding, are under 18, or have ever had an eating disorder. Stop and seek help if you feel unwell.

People often ask these same things on Reddit, for example in threads about 16:8 versus 18:6, whether most people's 16 hours is really 16, social dinners and when it gets easier.