Intermittent Fasting 16:8: Schedule, Rules, Results and Mistakes

With 16:8 fasting you eat only within an 8 hour window. It helps many people eat fewer calories, but research shows it is no better than other diets.

What is 16:8 intermittent fasting?

Intermittent fasting is not a diet that tells you what to eat. It is an eating pattern that tells you when to eat. In the 16:8 method, also called time restricted eating, you fast for 16 hours each day and eat all your meals inside an 8 hour window. For example, you might eat between 12 noon and 8 pm, then fast from 8 pm until noon the next day. Since you sleep for part of that time, many people find it easier than it sounds. In practice it often means skipping breakfast or eating dinner earlier.

Other fasting patterns

12:12 or 14:10. A gentler start, with a 10 to 12 hour eating window.
18:6 and 20:4. Shorter windows for people who are experienced and comfortable.
5:2. You eat normally for five days and reduce calories to about 500 to 600 on two non consecutive days.
Alternate day fasting. You alternate between normal days and very low calorie days.
One meal a day (OMAD). A single large meal, which is hard to sustain and makes it difficult to reach protein needs.

For most beginners, 14:10 or 16:8 is the most practical choice.

How might intermittent fasting help?

During a fast, insulin levels fall, and your body starts to draw more on stored fat for energy. The effects you notice most are probably simple ones:

Fewer calories. A shorter eating window usually means fewer meals and snacks, and less late night eating.
Simplicity. Some people prefer a rule about timing to counting every calorie.
A break from grazing. Fasting can separate you from constant snacking.
Possible metabolic benefits. Small studies suggest improvements in insulin sensitivity and blood pressure, but these often depend on weight loss itself.

What does the research say about weight loss?

This is where honesty matters, because the marketing is louder than the science.

A 12 week randomised trial published in JAMA Internal Medicine by Lowe and colleagues compared 16:8 eating with normal meal timing. The 16:8 group did not lose significantly more weight than the control group, and they also lost some lean mass.
A 12 month trial published in the New England Journal of Medicine by Liu and colleagues compared calorie restriction alone with calorie restriction plus an 8 hour eating window in adults with obesity. Time restricted eating did not add extra weight loss.
Other small studies, such as work by Cienfuegos and colleagues on 4 and 6 hour windows, found weight losses of around 3 percent over eight weeks, mainly because people ate less.

The practical conclusion is that intermittent fasting works for weight loss in the same way other diets do, by helping you consume fewer calories than you burn. It is not a metabolic shortcut. If you enjoy it and can stick with it, it is a valid tool. If it makes you miserable, you do not need it.

For more on the evidence, read intermittent fasting: an honest look.

How to start 16:8 step by step

Choose your window. Pick one that matches your life. Many people eat from 12 noon to 8 pm. Others prefer 10 am to 6 pm.
Ease in. Start with a 12 hour fast, move to 14 hours after a week, and then to 16 hours.
Plan your first meal. Break your fast with protein and fibre, not sweets.
Stay hydrated. Drink water, plain tea or black coffee during the fast.
Plan two or three meals inside the window rather than constant snacking.
Be consistent for at least two to three weeks before judging results.

What can you drink while fasting?

Water, still or sparkling.
Black coffee and plain tea, without sugar, honey, milk or syrup.
Unsweetened herbal tea.

Anything with calories technically breaks the fast. A splash of milk is a small break and many people accept it, but a latte is not fasting.

A sample 16:8 day

12:00 first meal: eggs, vegetables, wholegrain bread or oats with yogurt, about 30 to 40 grams of protein.
3:30 pm snack or second meal: yogurt with fruit and nuts, or a protein shake.
7:00 pm last meal: chicken or fish with rice or potatoes and a big salad.
8:00 pm to 12:00 pm: fast, with water, tea and black coffee.

Two good first meals from the Sports Kitchen are baked egg with potato and zucchini, a light dish with about 40 grams of protein, and Cobb salad with grilled chicken and egg, which has about 69 grams of protein.

What about muscle?

If you train, protect your muscle. The risk with a short eating window is that you under eat protein. Aim for 1.6 to 2.2 grams of protein per kilogram of body weight, divided between at least two or three meals of 25 to 40 grams each. Keep lifting weights. A combination of resistance training and enough protein is what keeps muscle during weight loss. Read intermittent fasting and muscle building and fasted training pros and cons.

What are the common side effects?

During the first week or two, you may feel hungry at your usual meal times, tired, irritable or headachy. These usually ease as your body adapts. Staying hydrated, getting enough sleep and not starting on a stressful week helps. If you feel dizzy or unwell, eat and rethink.

Who should not do intermittent fasting?

Talk to a doctor first, or avoid it, if you:

Are pregnant or breastfeeding.
Have a history of an eating disorder.
Have type 1 diabetes, or take insulin or other diabetes medicine, because fasting can cause low blood sugar.
Are underweight or have unintentional weight loss.
Are under 18.
Take medicines that must be taken with food.
Have a medical condition affecting digestion or blood sugar.

Common mistakes

Overeating in the window. An 8 hour window is not permission to eat everything. Calories still decide weight change. See how many calories should I eat to lose weight.
Too little protein. This causes hunger and muscle loss.
Choosing ultra processed food because you are very hungry. Plan meals ahead.
Skipping water. Thirst often feels like hunger.
Forcing it on poor sleep days. Sleep affects hunger hormones. Read how sleep affects weight loss and muscle growth.
Ignoring your social life. If family dinners matter, move your window rather than skip them.
Expecting speed. If the scale stalls, read weight loss plateau: why the scale stopped moving.

Intermittent fasting and Ramadan

Fasting in Ramadan is different from 16:8. In Ramadan you avoid both food and water from dawn to sunset, and the fasting hours depend on the season and your location. Many people then overeat at iftar. Our guide to nutrition considerations during Ramadan fasting for athletes offers practical advice. If you want to use time restricted eating outside Ramadan, treat it as a separate plan.

How many meals should you eat?

Meal frequency matters less than total calories and protein. Some people thrive on two big meals and a snack, others on three. Our guide to how many meals a day you should eat explains this in detail.

Is intermittent fasting right for you?

Choose it if it suits your routine and makes it easier to hit your calorie target. Do not choose it just because it is popular. A simple test: after two weeks, are you more consistent, less hungry and happier with your energy? If yes, keep going. If you feel worse, change your approach. A standard plan with three balanced meals, enough protein and a sensible deficit will work just as well.

Frequently asked questions

Does breakfast really matter? Not by itself. What matters is your total daily intake and quality of food. Some people feel better with a morning meal and some without.

Will intermittent fasting slow my metabolism? Short daily fasts do not slow metabolism in a meaningful way. Severe, long term calorie restriction can.

Can I exercise while fasting? Yes, for light and moderate exercise. Many people prefer to train near their eating window for harder sessions.

Can I take supplements while fasting? Water soluble vitamins and electrolytes without calories are generally fine. Protein powder and BCAAs contain calories and break the fast.

How long until I see results? Most people notice changes after three to four weeks when combined with a calorie deficit.

This article is general information and not medical advice. If you have a medical condition or take medication, speak with your doctor or a registered dietitian before fasting.

How FiTPLATE supports your eating schedule

An eating window works best when your meals are planned.

Meal reminders. Set reminder times for the start and end of your window, so you never miss a meal.
A daily log with live totals. Log meals by search, barcode or quick add and see your calories and protein fill up inside your window.
A protein target that fits two or three meals. FiTPLATE calculates your daily protein so you can divide it between fewer, larger meals.
Meals built for your window. Take a photo of your fridge and ask FiTPLATE for a high protein meal, or browse the Sports Kitchen.
A weekly plan and shopping list so your first meal is always ready.

Start your free trial and plan your eating window

References

Lowe DA et al. Effects of time restricted eating on weight loss and other metabolic parameters in women and men with overweight and obesity: the TREAT randomized clinical trial. JAMA Internal Medicine, 2020.
Liu D et al. Calorie restriction with or without time restricted eating in weight loss. New England Journal of Medicine, 2022.
Cienfuegos S et al. Effects of 4 and 6 h time restricted feeding on weight and cardiometabolic health: a randomized controlled trial in adults with obesity. Cell Metabolism, 2020.