16:8 intermittent fasting is an eating pattern where you fast for 16 hours and eat within an 8-hour window each day. It is the most popular intermittent fasting protocol because it fits naturally into most schedules and does not require radical changes to what you eat.
This guide covers how 16:8 works, how to start safely, common mistakes, and how to track your progress.
What is 16:8 intermittent fasting?
16:8 is a time-restricted eating pattern. You divide each 24-hour day into two windows:
- Fasting window: 16 hours. No food, only water, plain coffee, plain tea, or other zero-calorie drinks.
- Eating window: 8 hours. All your meals and calories happen here.
A common 16:8 schedule looks like this:
- Stop eating at 8:00 PM
- Sleep through most of the fast
- Skip breakfast
- Break the fast at 12:00 PM with lunch
- Eat normally until 8:00 PM
You can shift the window earlier or later depending on your lifestyle. Some people eat from 9:00 AM to 5:00 PM. Others prefer 1:00 PM to 9:00 PM. The 16-hour fast and 8-hour eating window are what define the protocol.
How does 16:8 work?
When you stop eating, your body shifts how it uses energy. In the first few hours after a meal, your body uses glucose from food. After roughly 8 to 12 hours without food, your liver glycogen depletes and your body increasingly relies on stored fat for energy.
The 16-hour fasting window pushes the body deeper into this fat-burning state on a daily basis. It also gives your digestive system extended rest and influences hormone levels related to insulin and growth hormone.
This is a simplified summary. The exact biological effects vary by person, and research is ongoing. Speak to a healthcare professional before starting any fasting protocol, especially if you have a medical condition or take medication.
Potential benefits of 16:8
People practice 16:8 for different reasons. Commonly cited benefits include:
- Easier calorie management. Compressing eating into 8 hours often reduces total calorie intake without active counting.
- Improved insulin sensitivity. Some studies suggest time-restricted eating may improve markers related to blood sugar control.
- Simplicity. No food groups are eliminated. The rule is when to eat, not what to eat.
- Cellular repair processes. Extended fasting periods are associated with autophagy, the body's process of clearing damaged cells.
- Mental clarity. Many practitioners report improved focus during the fasting window, though individual experience varies.
These benefits depend on overall diet quality, sleep, exercise, and individual physiology. Fasting alone does not override poor nutrition.
How to start 16:8
Going from a normal eating pattern to a 16-hour fast on day one is harder than it needs to be. A gradual approach works better for most people.
Week 1: 12-hour fast. Stop eating after dinner at 8:00 PM and wait until 8:00 AM to eat breakfast. This is barely different from a normal sleep schedule.
Week 2: 14-hour fast. Push breakfast to 10:00 AM. You will feel slightly hungrier in the morning, but it is manageable.
Week 3: 16-hour fast. Push your first meal to 12:00 PM. This is full 16:8.
By easing in, you let your body adjust gradually instead of forcing a sudden change.
What you can drink while fasting
During the fasting window, stick to zero-calorie drinks:
- Water (still or sparkling)
- Plain black coffee
- Plain tea (green, black, herbal)
- Electrolyte drinks with no sugar or calories
Avoid anything with calories, including milk in coffee, cream, sugar, juice, soda, alcohol, and bone broth. Even small amounts of calories can break your fast and reduce the protocol's intended effects.
What to eat in your 8-hour window
16:8 does not specify what to eat. But the protocol works better when your eating window contains nutrient-dense food rather than ultra-processed snacks.
A reasonable approach:
- Protein at every meal. Eggs, fish, chicken, beef, tofu, lentils, Greek yogurt.
- Plenty of vegetables. Aim for variety and color.
- Healthy fats. Olive oil, avocado, nuts, seeds.
- Complex carbs. Oats, rice, potatoes, whole grains in reasonable portions.
- Fruit. Especially berries and seasonal options.
Avoid using your eating window as a license to binge. Many people accidentally undo the calorie benefit of 16:8 by eating large portions of low-quality food in 8 hours.
Common 16:8 mistakes
Eating too much in the window. If you compensate by overeating, you cancel the calorie deficit.
Drinking flavored coffee or "skinny" lattes. Even small amounts of milk, syrup, or artificial sweeteners can break your fast.
Going too aggressive on day one. Jumping from 3 meals plus snacks to a 16-hour fast often leads to giving up. Ease in.
Ignoring sleep. Most of your fast happens while you sleep. Poor sleep undermines hunger regulation and makes fasting harder.
Skipping protein. Without enough protein during your eating window, you may lose muscle mass alongside fat.
Obsessing over the timer. A 15-minute deviation does not ruin the protocol. Consistency over weeks matters more than perfection on any single day.
How to track 16:8
Tracking helps with consistency. You do not need to track macros or calories to do 16:8, but knowing your fasting and eating windows is useful, especially when starting out.
A fasting tracker app handles this automatically. You set your protocol, tap start when you finish your last meal, and the app shows the timer and reminds you when your eating window opens. Easy Fast supports 16:8 as a default protocol along with 18:6, 20:4, OMAD, and 5:2.
The advantage of an app over a manual timer is consistency. You build a history, see patterns over weeks, and avoid forgetting when you ate.
When 16:8 might not work for you
16:8 is generally considered safe for healthy adults, but it is not appropriate for everyone. Avoid or consult a doctor first if you:
- Are pregnant or breastfeeding
- Have a history of disordered eating
- Have diabetes or take medication that affects blood sugar
- Are underweight
- Are under 18
If you experience persistent dizziness, fatigue, or other symptoms after a few weeks of 16:8, the protocol may not suit your physiology. Stop and consult a healthcare professional.
Frequently asked questions
Is 16:8 intermittent fasting effective for weight loss?
16:8 can support weight loss when combined with reasonable food choices. The protocol naturally reduces calorie intake for many people by compressing the eating window. Results vary based on overall diet, sleep, and activity level.
Can I drink coffee during a 16:8 fast?
Yes, but only plain black coffee. Adding milk, cream, sugar, or syrup introduces calories that break the fast.
How long does it take to see results with 16:8?
Most people notice changes in hunger patterns within 2 to 3 weeks. Visible weight or body composition changes typically take 4 to 8 weeks of consistent practice.
Is 16:8 better than 18:6 or OMAD?
16:8 is the most beginner-friendly protocol because it requires the least lifestyle adjustment. 18:6 and OMAD push the fasting window longer and may produce stronger effects but are harder to sustain.
Do I need an app to do 16:8?
No, but a tracker helps with consistency. Apps like Easy Fast time your fasts automatically, send reminders, and build a history without requiring you to count hours manually.
Easy Fast is a free intermittent fasting tracker for iPhone that supports 16:8 and other common protocols. Download Easy Fast on the App Store.
Ready to start tracking your fasts?
Easy Fast is free to download. Track 16:8, 18:6, 20:4, OMAD, and 5:2 with one tap.