18:6 Intermittent Fasting: Schedule, What to Eat & How to Start
18:6 intermittent fasting means you fast for 18 hours and eat all of your food within a 6-hour window each day, for example from 12pm to 6pm. During the fast you drink only water, black coffee, or plain tea. During the window you usually eat two balanced meals, sometimes with a small snack. It is one step longer than the popular 16:8 schedule and is usually easier to start after a few weeks of 16:8.
This page gives you sample 18:6 schedules, what to eat and drink, how 18:6 compares with 16:8, what the research does and does not show, and how to start without constant hunger or headaches.
18:6 at a Glance
- Sample schedule: eat from 12pm to 6pm, fast from 6pm until 12pm the next day. Most of the fast happens overnight while you sleep.
- During the 18-hour fast: water (still or sparkling), black coffee, plain unsweetened tea, and a pinch of salt or electrolytes in water if needed.
- During the 6-hour window: two meals built around protein (eggs, fish, poultry, tofu, beans, yogurt), vegetables, fiber-rich carbohydrates (whole grains, potatoes, legumes, fruit), and some healthy fat (olive oil, nuts, avocado).
- How to start: practice 16:8 first, then move to 17:7 for about a week, then 18:6.
- Who should not try it without medical advice: people who are pregnant or breastfeeding, under 18, underweight, have a history of eating disorders, or take insulin or other blood sugar-lowering medication.
Table of Contents
- What Is 18:6 Fasting
- How It Differs from 16:8
- Potential Benefits and What the Evidence Says
- Who It Suits (and Who Should Avoid It)
- Daily Schedule Examples
- What to Eat: Meal Planning and a Sample Day
- How to Start: Adaptation Tips
- Common Challenges and Solutions
- Exercise and 18:6 Fasting
- Making 18:6 Sustainable
What Is 18:6 Fasting
18:6 is a form of time-restricted eating: you eat within the same 6-hour window each day and fast for the remaining 18 hours. It does not dictate which foods you eat, although food quality still matters. It sits between 16:8 (an 8-hour eating window) and more demanding schedules such as 20:4 or one meal a day (OMAD).
Understanding the Numbers
Breaking Down 18:6
- 18 hours: the fasting period, when you have only zero-calorie drinks (water, black coffee, plain tea)
- 6 hours: the eating window, when you eat all of the day's meals
- Daily cycle: the pattern repeats every 24 hours
- Flexibility: keeping roughly the same window each day makes it easier, but you can shift it on days when your schedule changes
Common 18:6 Eating Windows
12pm - 6pm Window
Fast from 6pm to 12pm the next day. The most common choice: you skip breakfast, eat lunch and an early dinner, and finish eating well before bed. Good for people who are not hungry in the morning.
1pm - 7pm Window
Fast from 7pm to 1pm the next day. The same idea shifted an hour later, which suits a later lunch and a more typical dinner time.
2pm - 8pm Window
Fast from 8pm to 2pm the next day. Works for people who eat dinner late or often have evening social meals. The trade-off is eating closer to bedtime.
11am - 5pm Window
Fast from 5pm to 11am the next day. An earlier window that ends in the late afternoon. Some research on earlier eating windows is promising, but this timing can be hard to fit around family or social dinners.
What You Can Have During Each Period
18-Hour Fasting Window
Generally fine:
- Water (still or sparkling)
- Black coffee (no milk, cream, or sugar)
- Plain unsweetened tea (green, black, or herbal)
- Salt or an unsweetened electrolyte mix in water, if needed
Best avoided:
- Anything with meaningful calories, including milk or cream in coffee
- Bone broth (it contains protein and calories; some people use it as a compromise, but it technically breaks a strict fast)
- Diet sodas and sweetened drinks (their effect on a fast is debated; see diet soda and sweeteners while fasting)
- Gum and mints, which often contain sugar or sweeteners
6-Hour Eating Window
This is when you eat all of your food for the day:
- Two substantial meals (most common)
- Two meals plus a small snack, or three smaller meals if you prefer
- Mostly minimally processed foods
- Enough protein, vegetables, fiber, and healthy fats
- Water throughout
Why People Choose 18:6
- A simple structure: two meals in a fixed window means fewer decisions about food
- A realistic eating window: 6 hours is enough for two unhurried meals
- A step beyond 16:8: some people who find 16:8 easy want to try a slightly longer daily fast
- More social room than OMAD: the window can include both lunch and dinner
Longer is not automatically better. There is little direct evidence that 18:6 produces better health outcomes than 16:8, so the best choice is the schedule you can follow comfortably while eating well.
How 18:6 Differs from 16:8
Both are daily time-restricted eating schedules. The difference is two more hours of fasting and two fewer hours of eating. For a side-by-side look that also includes OMAD, see 16:8 vs 18:6 vs OMAD.
What Changes Physiologically
After the last meal, the body gradually shifts from using recently eaten carbohydrate toward stored glycogen and fat. Ketone levels tend to rise slowly the longer a fast lasts, and insulin stays low while you are not eating. Two extra hours of fasting may extend these changes somewhat, but the size of the difference between 16 and 18 hours has not been well studied in humans and varies with what you ate, how active you are, and your metabolic health.
Autophagy (the cell's process for breaking down and recycling its own components) is often mentioned in connection with 18:6. It is well documented in animal and cell studies, but there is no reliable way to measure it in everyday human fasting, and no established timeline for when it "starts" or "peaks" in people. Treat claims about 18:6 "maximizing autophagy" with caution. See autophagy and fasting for more detail.
Daily Experience Compared
16:8 vs 18:6
| Aspect | 16:8 | 18:6 |
|---|---|---|
| Eating Window | 8 hours | 6 hours |
| Typical Meals | 2-3 meals, possibly snacks | 2 meals, possibly a small snack |
| Difficulty | Common starting point for beginners | Harder; usually easier after 16:8 |
| Social Flexibility | High | Moderate; needs more planning |
| Hunger | Usually manageable after a couple of weeks | Often noticeable in the last hours at first |
| Getting Enough Nutrition | Easier | Needs more deliberate meals, especially for protein |
Consider Moving from 16:8 to 18:6 If You
- Have followed 16:8 comfortably for at least 4-6 weeks
- Rarely feel strong hunger during your current fast
- Can easily eat enough in two meals
- Have a schedule that allows a consistent 6-hour window most days
- Simply prefer eating two larger meals
Consider Staying with 16:8 If You
- Are new to intermittent fasting
- Still struggle with hunger during 16-hour fasts
- Have a variable schedule or frequent social meals
- Are already meeting your goals with 16:8
- Find it hard to eat enough protein and vegetables in a shorter window
- Notice worse sleep, mood, or energy when you eat less often
Some people find it helps to alternate, following 18:6 on regular weekdays and 16:8 on weekends or busy days. Neither schedule is "better" for everyone.
Potential Benefits and What the Evidence Says
Most research on time-restricted eating has studied 16:8 or similar windows (roughly 6-10 hours), usually over weeks to months and in relatively small groups. Very few studies have tested 18:6 specifically. What follows is what the broader research suggests, with its limits.
Weight and Body Composition
Weight Loss
A shorter eating window often leads people to eat less without counting calories, and many studies of time-restricted eating report modest weight loss. However, when trials compare time-restricted eating with ordinary calorie restriction at the same calorie level, results are usually similar. In other words, the main driver appears to be eating less overall, and 18:6 is one way some people find that easier.
Blood Sugar and Insulin
Some studies have observed improvements in fasting insulin, insulin sensitivity, or blood sugar with time-restricted eating, especially with earlier eating windows and in people with prediabetes or overweight. Results are mixed and often tied to weight loss. Anyone taking medication for diabetes should speak with their healthcare provider before fasting, because fasting can cause low blood sugar with some medications.
Muscle
Fasting itself does not build muscle. Studies combining time-restricted eating with resistance training suggest muscle can be maintained if protein intake is adequate. With only two meals, getting enough protein takes some planning.
Everyday and Practical Benefits
Simpler Routine
Many people like having clear times for eating and not eating. Fewer meals can mean less planning, cooking, and snacking.
Less Late-Night Eating
A window that closes in the early evening removes late-night snacking, which is often a source of extra calories.
Energy and Focus
Some people report feeling alert during fasted mornings; others feel tired, irritable, or distracted. These are individual experiences rather than established effects, and they often change during the first few weeks.
What Is Still Uncertain
Claims that 18:6 "boosts growth hormone," "maximizes autophagy," "heals the gut," or slows aging are not supported by good human evidence for this schedule. Long-term effects on heart disease, diabetes risk, and lifespan have not been established. For a broader overview, see the benefits of intermittent fasting and our summary of fasting research.
Individual Responses Vary
How you respond to 18:6 depends on your starting health, what you eat in your window, sleep, stress, activity, and how consistently you follow it. Some people do well on 18:6; others feel better on 16:8, 14:10, or regular meal timing.
Who 18:6 Suits (and Who Should Avoid It)
People Who Often Do Well with 18:6
Experienced 16:8 Fasters
People who have followed 16:8 for several weeks and feel comfortable during the fast are the most natural candidates.
People Who Prefer Fewer, Larger Meals
If you naturally prefer two satisfying meals over several small ones, 18:6 fits that preference.
People with Busy, Predictable Days
A regular routine makes it easier to keep the same 6-hour window each day.
Who Should Avoid 18:6 or Get Medical Advice First
Important Safety Cautions
- Pregnant or breastfeeding: nutritional needs are higher; fasting is not recommended
- Children and teenagers: still growing and need regular meals (see fasting and teenagers)
- History of eating disorders: a strict eating window can trigger restrictive or binge patterns
- Underweight or struggling to eat enough: a short window makes adequate intake harder
- Diabetes, especially on insulin or sulfonylureas: risk of low blood sugar; medication changes need medical supervision (see diabetes and fasting)
- Medications that must be taken with food at set times: check with your doctor or pharmacist (see fasting and medications)
- Other medical conditions: including low blood pressure, kidney disease, or a history of fainting
When a Shorter Window May Be a Better Fit
- You are new to fasting: start with 12:12, 14:10, or 16:8
- You have high energy needs: very active people and athletes may struggle to eat enough in 6 hours
- You have a physically demanding job or train hard most days
- You tend to overeat after long gaps: a longer window may feel less restrictive
- You value social flexibility: an 8-hour window accommodates more shared meals
Special Considerations
Women
Some women notice changes in their menstrual cycle, sleep, or mood with longer daily fasts. Starting with a shorter window and adjusting based on how you feel is a sensible approach. Stop and speak with a healthcare provider if your cycle becomes irregular. See intermittent fasting for women.
Adults Over 50
Maintaining muscle becomes more important with age, so protein at both meals matters. See fasting after 50.
Active People and Athletes
Place your eating window around your training so you can eat before and/or after hard sessions. See the exercise section below.
Quick Readiness Checklist
- Have I followed 16:8 or a similar schedule comfortably for at least 4-6 weeks?
- Can I eat enough protein, vegetables, and total food in two meals?
- Can I keep a consistent 6-hour window most days?
- Am I free of the medical situations listed above, or have I discussed fasting with my healthcare provider?
- Do I have a healthy relationship with food?
If you answer "no" to several of these, a shorter window is likely a better starting point.
Daily Schedule Examples
These are example schedules to adapt, not rules. Pick a window that fits your work, sleep, and family meals.
Schedule 1: 12pm-6pm (Most Common)
Previous Evening: Window Closes
Finish dinner by 6pm. Water or herbal tea in the evening if you like.
Morning: Fasting Hours
Wake up, drink water, and have black coffee or tea if you usually do. Most of the 18 hours have already passed overnight.
First Meal
A balanced, filling meal. Example: grilled chicken or chickpea salad with greens, vegetables, olive oil dressing, and a slice of whole-grain bread.
Optional Snack
Only if hungry: Greek yogurt with fruit, a handful of nuts, or hummus with vegetables.
Second Meal (Dinner)
Example: salmon or tofu with roasted vegetables and rice or potatoes. Finish by 6pm and the next fast begins.
Schedule 2: 2pm-8pm (Later Window)
Suits: people who are not hungry until the afternoon or who often eat dinner with others later in the evening.
- 8:00 PM (previous day): last food; the fast begins
- Morning to 2:00 PM: water, black coffee, or tea
- 2:00 PM: first meal (late lunch)
- 5:00 PM (optional): small snack
- 7:30 PM: dinner
- 8:00 PM: window closes
Consider: eating close to bedtime disturbs sleep or causes reflux for some people. Try to finish eating 2-3 hours before bed.
Schedule 3: 11am-5pm (Earlier Window)
Suits: early risers and people who prefer not to eat in the evening.
- 5:00 PM (previous day): last food
- Morning to 11:00 AM: water, black coffee, or tea
- 11:00 AM: first meal (brunch-style)
- 2:00 PM (optional): small snack
- 4:30 PM: early dinner
- 5:00 PM: window closes
Consider: some studies suggest earlier eating windows may be kinder to blood sugar, but evidence is still limited, and this schedule can clash with family or social dinners.
Schedule 4: Flexible Week
Suits: people whose days vary.
- Monday-Thursday: 12pm-6pm (work days)
- Friday: 1pm-7pm (dinner out)
- Saturday: 11am-5pm or a relaxed 16:8
- Sunday: 12pm-6pm (family meal)
Shifting the window by an hour or two occasionally is fine. Consistency makes the routine easier, but it does not need to be perfect.
How to Choose Your Window
- Sleep: aim to finish eating 2-3 hours before bed
- Work: place your first meal where a lunch break naturally falls
- Exercise: if you train hard, try to eat soon after your workout
- Family and social life: include the meals that matter most to you
- Hunger: notice when you are genuinely hungry and work with it
Tip: the free fasting timer on our homepage can help you track when your fast started and when your eating window opens.
What to Eat: Meal Planning and a Sample Day
18:6 does not require a special diet, but with only two main meals, each one needs to count. A simple template: protein + vegetables + a fiber-rich carbohydrate + some healthy fat at each meal.
Meal Structure Within the 6-Hour Window
Two Meals (Most Common)
Two balanced meals about 4-5 hours apart. Simple to plan and filling enough to carry you through the fast.
Two Meals Plus a Snack
Helpful if you find it hard to eat enough in two sittings, or if you get very hungry before dinner.
Three Smaller Meals
Works for people who dislike large portions, for example at 12pm, 3pm, and 5:30pm.
Breaking Your Fast
Good First-Meal Principles
- Include protein: it helps with fullness
- Add vegetables and fiber: for nutrients and steady digestion
- Choose mostly whole-food carbohydrates: such as whole grains, beans, potatoes, or fruit, rather than sweets or refined snacks
- Include some fat: olive oil, nuts, seeds, avocado
- Eat at a normal pace: a very large meal eaten quickly can cause discomfort
More ideas: how to break a fast.
First Meal Ideas
- Protein salad: chicken, salmon, eggs, or beans over mixed greens with avocado, nuts, and olive oil dressing
- Vegetable omelet: eggs with vegetables and cheese, whole-grain toast, and berries
- Grain bowl: quinoa or brown rice with roasted vegetables, chickpeas or chicken, and tahini sauce
- Soup and salad: chicken and bean or lentil soup with a side salad
- Yogurt bowl: Greek yogurt with fruit, oats, and nuts (a lighter option)
Second Meal Ideas
- Stir-fry: chicken, tofu, or shrimp with mixed vegetables over rice
- Fish tacos: grilled fish in corn tortillas with cabbage slaw and avocado
- Mediterranean plate: grilled chicken or falafel, hummus, salad, olives, and whole-grain pita
- Stew or chili: beef, chicken, or bean chili with plenty of vegetables
- Salmon and potatoes: baked salmon with roasted broccoli and sweet potato
Nutrition Targets to Keep in Mind
Meeting Daily Needs in 6 Hours
- Protein: the general adult minimum is about 0.8 g per kg of body weight per day; many active people and older adults aim higher (often around 1.2-1.6 g/kg). Splitting it roughly evenly across two meals is practical.
- Fiber: commonly recommended amounts are about 25-38 g per day for adults, from vegetables, fruit, legumes, and whole grains
- Healthy fats: fish, nuts, seeds, olive oil, avocado
- Vitamins and minerals: a variety of colorful vegetables and fruit
- Fluids: drink water through both the fast and the eating window
Your needs depend on your size, age, activity, and health. A registered dietitian can help you set personal targets.
Sample Day of Eating (about 2,000 calories)
This is an example only. Adjust portions to your own needs.
First Meal (about 850-900 calories)
Large Mediterranean salad:
- Mixed greens and spinach
- About 5-6 oz (150-170 g) grilled chicken breast
- Half an avocado, a few olives, cherry tomatoes, cucumber
- A quarter cup of chickpeas
- Olive oil and lemon dressing
- A slice of whole-grain bread
Optional Snack (about 200 calories)
- A small handful of almonds (about 1 oz)
- An apple
Second Meal (about 850-900 calories)
Salmon and vegetables:
- About 5-6 oz (150-170 g) baked salmon
- Roasted broccoli and cauliflower
- A medium sweet potato with a little butter or olive oil
- Side salad with olive oil dressing
For more complete menus, see intermittent fasting meal plans.
Meal Prep Tips
Make Two-Meal Days Easy
- Batch-cook protein: chicken, lentils, hard-boiled eggs, or tofu for quick meals
- Pre-chop vegetables: ready for salads and stir-fries
- Cook soups and stews in bulk: they reheat well
- Keep frozen vegetables and canned beans on hand: quick, inexpensive, and nutritious
- Keep it simple: protein + vegetables + carbohydrate + fat is enough
Common Meal Planning Mistakes
Not Eating Enough Protein
Include a clear protein source at both meals. Tracking for a few days can help you learn portion sizes.
Overeating at the First Meal
Start with a normal portion. Another meal is coming in a few hours.
Too Few Vegetables
Try filling about half your plate with vegetables at each meal.
Eating Too Little Overall
Consistently undereating can lead to fatigue, irritability, and poor recovery. 18:6 is a timing pattern, not a reason to eat as little as possible.
How to Start: Adaptation Tips
Most people find 18:6 easier if they build up to it gradually rather than jumping straight in.
A Gradual Progression
Start with 16:8 (or Shorter)
If you are not already fasting, begin with 12:12 or 14:10 and work up to 16:8. See our 16:8 guide.
Move to 17:7
Add one hour by starting your first meal 30 minutes later and finishing dinner 30 minutes earlier.
Reach 18:6
Add the final hour. If this feels too hard, stay at 17:7 for another week or two.
Settle In
Keep a consistent window. Many people find that hunger in the last hours of the fast becomes easier over the first few weeks, though experiences vary.
Getting Through the First Weeks
Drink Enough Fluids
Drink water regularly during the fast. Mild dehydration can feel like hunger, fatigue, or a headache.
Consider Electrolytes
Some people get headaches or feel lightheaded when they start fasting. Salting food normally and including potassium-rich foods can help. A pinch of salt in water during the fast works for some. People on salt-restricted diets or with blood pressure, heart, or kidney conditions should check with their healthcare provider first. See electrolytes and fasting.
Use Caffeine Sensibly
Black coffee or tea can make mornings easier for some people, but too much can cause jitters, stomach upset, or poor sleep. Avoid caffeine late in the day.
Go Easier on Hard Training at First
For the first couple of weeks, keep workouts at a comfortable intensity until you know how you respond.
Common Early Problems
Strong Hunger in the Last Hours
- Drink water or herbal tea; a hunger wave often passes after a while
- Keep busy during the hardest hours
- Make sure your last meal includes protein, fiber, and some fat
- If it stays overwhelming, go back to 17:7 or 16:8 for longer
Afternoon Tiredness
- Avoid a very large first meal
- Take a short walk after eating
- Check that you are sleeping enough (7-9 hours is recommended for most adults)
Difficulty Eating Enough
- Add a snack between meals
- Include energy-dense whole foods such as nuts, seeds, olive oil, avocado, and dairy
- Consider a smoothie with yogurt or milk as part of one meal
- If you still cannot eat enough, a longer window is a better fit
When to Stop or Adjust
Return to a longer eating window, or stop fasting and speak with a healthcare provider, if you experience:
- Dizziness, fainting, heart palpitations, or confusion
- Ongoing fatigue that does not improve after the first couple of weeks
- Mood changes or irritability that affect daily life
- Worse sleep
- Binge eating or feeling out of control around food
- Missed or irregular periods
- Unintended or excessive weight loss
See fasting side effects and fasting safety for more.
Signs It Is Working for You
- The fast feels manageable without constant willpower
- Energy is steady for most of the day
- Two meals leave you comfortably satisfied
- Sleep is unchanged or better
- You are moving toward your goals without feeling deprived
Common Challenges and Solutions
Social Meals and Eating Out
- Shift the window: for a planned dinner, move that day's window later (for example 2pm-8pm)
- Decide in advance: choose which occasions are worth adjusting for
- Keep it short: "I usually eat between noon and six" is enough explanation; you can join with tea or coffee
- Allow exceptions: following 18:6 most days, not every day, is still a reasonable routine
Weight Loss Stalls
- Check intake: it is easy to eat more than you realize in a short window; log food for a few days
- Look beyond the scale: waist measurements and how clothes fit can change even when weight does not
- Review sleep, stress, and activity: all affect appetite and weight
- Focus on food quality: the window does not cancel out large amounts of highly processed food
- Be patient: day-to-day weight fluctuations are normal; look at trends over several weeks
More ideas: breaking a fasting plateau.
Weekends and Holidays
- Switch to 16:8 or 14:10 on busy social days
- Shift the window to include the important meal
- Return to your usual schedule the next day without trying to "make up" for it with a longer fast
Digestive Discomfort
- Start the first meal with a normal portion and eat slowly
- Increase fiber gradually if you are adding more vegetables and legumes than usual
- Drink enough water during the eating window
- Notice which foods bother you after a fast and adjust
Family Meals
- Choose a window that includes the main family meal
- Cook one meal that works for everyone rather than separate meals
- Do not pressure family members, especially children, to fast
Cravings During the Fast
- Drink water or tea first
- Notice whether the craving is habit, boredom, or stress rather than hunger
- If you crave a particular food, plan to include it in your eating window
- Frequent strong cravings can be a sign that you are not eating enough during your window
If Problems Keep Coming Back
Ask yourself whether you are combining too much at once (a large calorie deficit, a long fast, and intense training), and whether 16:8 or a regular eating pattern would suit you better right now. The goal is better health and well-being, not strict adherence to a schedule. Our common fasting mistakes page covers more pitfalls.
Exercise and 18:6 Fasting
You can exercise on an 18:6 schedule. The main decision is whether to train during the fast or during your eating window.
Training Fasted
Light to moderate exercise such as walking, easy cycling, or yoga is comfortable for many people before the first meal. Some people prefer it; others feel weak or lightheaded. Research does not show that fasted training produces more fat loss over time than fed training when total intake is similar. See fasted cardio.
Training Fed
Strength training, high-intensity intervals, and long endurance sessions usually feel better with food beforehand, and eating protein after training supports recovery.
Example Training Schedules (12pm-6pm Window)
Late-Morning Session, Then Eat
Train at 10-11am, then have your first meal at noon. Suits moderate cardio or lighter workouts.
Train After the First Meal
Eat at noon, train around 2-3pm, and have dinner at 5:30pm. Suits strength and high-intensity training.
Train Before Dinner
Eat at noon, train at 4-5pm, and eat dinner right after. Suits people who prefer evening workouts.
Nutrition Around Training
- Include a good protein source in the meal after training
- Include carbohydrates if you do intense or long sessions
- Drink water before and during exercise; for long or sweaty sessions, electrolytes may help
- If you train hard on most days and cannot eat enough in 6 hours, widen the window
Signs to Adjust
- Performance keeps declining after the first few weeks
- You cannot finish your usual sessions
- Recovery is poor, or you feel dizzy during exercise
- Sleep or mood gets worse
If you notice these, try training after a meal, widening your eating window, or eating more. See exercise and fasting for more.
Making 18:6 Sustainable
Keep the Basics Consistent
- Keep a similar window most days: routine makes hunger more predictable
- Prioritize food quality: protein, vegetables, fiber, and healthy fats at each meal
- Protect your sleep: finish eating a few hours before bed and keep a regular bedtime
- Stay active: regular movement and strength training support health whatever your eating schedule
Track What Matters
How You Feel
- Energy and focus
- Sleep quality
- Hunger and cravings
- Mood
- Exercise performance
Measurements
- Weekly average body weight rather than daily readings
- Waist measurement
- Blood pressure, if you monitor it
- Routine blood tests with your healthcare provider
See tracking your fasting progress for ideas.
Flexible Variations
- 18:6 on weekdays, 16:8 on weekends: a common compromise for social flexibility
- 18:6 with a particular eating style: such as Mediterranean or lower-carbohydrate eating, if that suits you (see fasting and the Mediterranean diet and keto and fasting)
- Stepping back to 16:8 during demanding periods: illness, travel, heavy training, or high stress
Longer or more frequent fasts are not required to get value from 18:6, and extended fasts carry more risks. Get medical advice before trying fasts longer than 24 hours.
Long-Term Habits
- Build in flexibility: most days on schedule, with exceptions when life calls for them
- Reassess every few months: is the schedule still helping?
- Listen to your body: change course if problems persist
- Look beyond weight: energy, sleep, and enjoyment of food matter too
The Bottom Line
18:6 intermittent fasting means eating within a 6-hour window, such as 12pm to 6pm, and fasting for the other 18 hours. It is a step up from 16:8 and suits people who are already comfortable with shorter fasts and like eating two larger meals.
Evidence for time-restricted eating in general points to modest benefits, mainly because it helps some people eat less. There is little evidence that 18:6 is better than 16:8, and it is harder to get enough nutrition in a shorter window. Build up gradually, eat balanced meals with enough protein, stay flexible, and choose a shorter window, or no fasting at all, if 18:6 does not suit you. If you have a medical condition or take medication, talk to your healthcare provider first.
Ready to Try 18:6?
Use our free fasting timer to track your 18-hour fasts, or compare other fasting schedules.