Intermittent fasting 16:8 — an expert guide for success

Written by Trey Reck

Medically reviewed by Josie Porter, RD

Published on November 18, 2022 | Updated on June 10, 2024

If you’ve considered improving your eating habits, you’ve likely wondered about intermittent fasting. 

It’s a method that captures our attention because it’s so simple:

• Some of the time, you eat. 
• Some of the time, you fast (i.e., don’t consume calorie-containing foods or drinks). 

There are different ways this can shake out on a day-to-day basis. Today, we’ll walk you through intermittent fasting 16:8 — one of the most uncomplicated intermittent fasting methods.

It’s effective, too! Research shows intermittent fasting delivers a host of health benefits, from lowering your blood pressure to keeping your brain happy. 

If you want to cut the clutter around eating with some straightforward guidelines that make room for your needs, preferences, and goals, you’re in the right place. 

What is 16:8 intermittent fasting?

16:8 intermittent fasting is simple: 

• For 16 hours a day, you’re fasting. (This isn’t as scary as it sounds.)
• For the remaining eight hours, you eat and drink what you need to nourish your body, mind, and spirit.

We hear you — 16 hours sounds like a long time.  It conjures mental images of tedious, never-ending shifts at work, or that family dinner that felt like 16 hours because when you got cornered by Uncle Blake, time just seemed to … stop. 

A 16-hour fast isn’t like that. In fact, you’ll probably be asleep for roughly half of it. 

If you can make peace with eating an early dinner or a late breakfast, you can excel at 16:8 intermittent fasting. 

Huh. That doesn’t seem so hard.

How to plan your 16:8 fasting schedule

Start by asking yourself some questions. 

• Which meal is most important to me? 
• If I miss breakfast or dinner — or if it’s late or early — what’s that like?
• When am I most hungry during my day? 
• Are there times when food is more necessary or convenient due to work, family, exercise, or social events?

Gather some data on what you notice about your own patterns. 

Then, choose when you want your fast to begin and end. 

Say you shoot for a late breakfast and early dinner. Your fasting period might be from 7 PM to 11 AM. 

If, however, you cannot skip breakfast without turning into a Very Unreasonable Person due to lack of food, you might prefer 5 PM to 9 AM. 

Ultimately, you’re looking for a 16:8 fasting schedule you can live with because following a predetermined plan both feels better and makes it easier to stay consistent.

Simple’s top tips: 

1. Schedule your fasting period when you are generally less hungry. This works with your appetite and reduces the possibility of hunger pushing you to break your fast early or eat more than you need.
2. Include your sleeping hours in your fast. (We probably don’t need to tell you that if you don’t, you’ll need to master eating while you sleep, which is — as far as we know — pretty tricky.)
3. Let us help you get up and running by trying our Simple quiz. We’ve supported a lot of people trying intermittent fasting, so you’ll be in good hands. 

What should you eat on a 16:8 intermittent fasting schedule?

When it comes to what to eat during intermittent fasting 16:8, there’s good news: 

16:8 intermittent fasting works with any eating plan. 

• During your 16-hour fasting window, eat nothing and drink only calorie-free drinks, like water and unsweetened tea or coffee. (Fancy coffees may be OK if they fit your goals.) 
• Focus on the timing of your eating window to help your body adapt to eating all your meals within eight hours.
• Close your eating window eight hours after you break your fast. 

Done!

Now, being more mindful of your food choices will help you squeeze the most out of your 16:8 fasting benefits, especially for goals like weight loss or improving your metabolic health.To optimize your 16:8 intermittent fasting results, shoot for high-quality foods like colorful veggies, quality protein, and healthy fats in your meals.

Is a 16:8 fasting schedule incompatible with breakfast?

Not at all!

Whether you can’t face anything more than a slosh of water to rinse your toothpaste first thing or you’re a breakfast connoisseur, no worries. 

Tailor your fasting schedule to fit your life. 

Five tips for 16:8 beginners

The intermittent fasting 16:8 method is straightforward, yet it’ll likely feel clunky at first as you mesh it with your eating patterns. 

These steps will help you get into the groove.

• Make your fasting window work for you. If a healthy dinner with your partner is a deal-breaker, adjust breakfast time to accommodate. And so on. 
• You’re likely to feel hungry in the beginning. Don’t worry, your body will adjust. Have some options ready to roll to distract you, like: 
  • playing a game 
  • listening to music
  • moving your body
  • drinking calorie-free drinks
  • doing a short meditation
  • getting some fresh air
• Stay hydrated, and shoot for a balanced diet of complex carbs, lean proteins, and healthy fats.
• Listen to your body. If you feel lightheaded, ill, faint, or shaky, 16:8 fasting might not be for you. If so, don’t worry. Maybe try a shorter fast, like 12:12 or 14:10. There are always other options. 
• Don’t be scared to make mistakes. You won’t get this perfect the first time around. That’s OK. Here are a few common intermittent fasting mistakes to watch out for so that you’re ahead of the game. 

If you’re female, be aware that intermittent fasting and hormones are a thing, and you could have an adverse physiological response to fasting longer than 12–14 hours. To keep you safe, start with a 12-hour fast, slowly work your way up to 16 hours, and always listen to your body.

16:8 intermittent fasting and weight loss

Let’s look at the benefits of 16:8 fasting on weight loss. Are there any?

Heck yeah! 

Restrictive diets don’t work. Studies show they don’t generate lasting or significant results.[1]

But intermittent fasting isn’t a diet. 

There’s no calorie restriction, deprivation, or gimmicks like “you may only ingest raw cabbage that’s been grown in the soil of an ancient forest.” 

It’s a lifestyle transformation. 

That makes 16:8 fasting weight loss results more sustainable. It’s an approach you can stick with in the long term. 

16:8 intermittent fasting results

Strap yourself in — we’re going to lay down some kickass, real-life, and science-backed results on you. 

Could you achieve a lower body weight without counting every calorie [yawn] through intermittent fasting? Studies show you could.[2]

Curious to know whether intermittent fasting helps with burning fat? It does! In one study, people who fasted reduced their waist circumference and belly fat.[3]

An intermittent fasting schedule 16:8 can also help you maintain muscle mass. (In fact, intermittent fasting might even be more efficient at maintaining muscle than traditional diets.)[4]

If you’re hungry for evidence, check out these studies to see more intermittent fasting 16:8 weight loss success examples.[5]

Risks and benefits of 16:8 intermittent fasting

Everything has positives and negatives, intermittent fasting included. 

The benefits

16:8 intermittent fasting packs some profound health benefits. For instance, intermittent fasting can lead to:

• Improved insulin sensitivity

There’s a well-established link between insulin sensitivity and weight loss,[6] but recent research shows intermittent fasting improves insulin sensitivity even without weight loss.[7] 

Research also indicates intermittent fasting has the potential to improve type 2 diabetes. Intermittent fasting helped patients improve their insulin resistance, maintain healthy blood sugars, and wean off their glucose-regulating medications.[8] 

Important note: If you’re taking diabetes medications, talk with your doctor to get the all clear before starting intermittent fasting.

• Lower blood pressure

In 2016, approximately 100 million Americans had high blood pressure (also known as hypertension; this is when your blood pressure is 140/90 or higher),[9] which is a risk factor for many diseases, including cardiovascular disease, stroke, and kidney disease. Here’s the good news: current research shows intermittent fasting has the potential to lower high blood pressure.[10]

• Improved cardiovascular health. 

Your heart health depends on multiple factors, including your weight, blood pressure, cholesterol levels, and blood sugar levels, all of which intermittent fasting can improve. A 2020 review showed that intermittent fasting improves cardiovascular health through oxidative stress reduction, circadian rhythm normalization, and ketogenesis.[11]

• Lower risk of metabolic disorders.

Intermittent fasting can help with your weight loss goals via the metabolic pathways activated by fasting, like ketogenesis, which in turn can help lower your risk of metabolic disorders like type 2 diabetes.[12] 

• Improved brain health. 

Multiple studies show intermittent fasting may support brain health by inducing ketosis (increasing neuroprotective protein production),[13] increasing neuroplasticity (helping your brain make more connections),[14] and more generally by helping us reach our health goals, which are often deeply significant both mentally and emotionally. 

Intermittent fasting may also help keep your spirits up.[15] If you want a brain that thinks good and feels good, maybe this benefit of 16:8 fasting will encourage you to get started!Intermittent fasting might also reduce the likelihood of some cancers and even help you live longer,[16] but more research is needed.

The risks 

Though the benefits are plenty, there are some possible risks.

It’s best to avoid intermittent fasting if you:

• have medical conditions that impact the pancreas, liver, thyroid, or gallbladder;
• are prescribed medication; 
• are pregnant, breastfeeding, or trying to conceive; 
• have a history of or are currently diagnosed with disordered eating; 
• are extremely active;
• have a BMI of less than 18.5; 
• are under 18 or 80 years old or older.

Important note: If you have type 1 diabetes or a history of disordered eating, intermittent fasting can be possible, but please, if you try it, make sure you are fully supported by a healthcare professional. Don’t go at it alone.

You may also experience:

• Weight gain. 

Hold up … doesn’t intermittent fasting help with weight loss? Yes. However, if you end up feeling overly hungry during your fast, it can be easy to eat more than you need. 

• Hunger. 

Initially, you may feel ravenous, but you can overcome this with time, practice, and thoughtfully scheduling your fasting and eating times. 

As you go through this natural hunger stage, try some ways to hack hunger while fasting, like drinking plenty of fluids, finding ways to distract yourself, and reassuring yourself that you won’t feel this way forever. 

• Feeling cold. 

Fasting can make you feel chilly, but it’s less likely on the 16:8 schedule than on more restrictive schedules like 5:2. If you feel cold, again, know that it’s temporary. Throw on an extra sweater and trust that this effect will disappear as you adapt.

• Mild dehydration. 

Because food provides some of your fluid intake, you can get dehydrated during your fast. So, drink plenty. What can you drink while fasting? Focus on calorie-free drinks like tea with no sugar or coffee with no milk. And remember to drink enough water.

Pros and cons of intermittent fasting 16:8

Let’s sum this up in a nice, quick, scannable list. 

The pros of intermittent fasting 16:8:

• It’s simple, easy, and flexible.
• It can be helpful in reducing unwanted snacking (no more late-night bargaining with the cookie jar!).
• It can improve blood sugar control, lower blood pressure and cholesterol levels, and increase brain health. 
• It can support achieving a lower body weight in the long term.

The cons of intermittent fasting 16:8:

• It can increase hunger and the possibility of eating more than you need and making less health-promoting food choices.
• It could make it harder for you to eat enough nutrients.
• It can clash with your social, family, or work commitments.
• It may initially leave you feeling hungry, brain-foggy, and low on energy.

This leads us to our million-dollar question …

Is the intermittent fasting 16:8 method right for you?

Now that you’ve gotten a grasp on how a 16:8 intermittent fasting schedule works, how do you feel about trying it?

Yes, simple, I’m in! 

If your brain is making “Huh! This sounds kinda … cool!” noises at the thought of a 16:8 intermittent fasting schedule that:

• is the same every day, Monday through Sunday
• lets you eat the food you want for eight hours a day
• allows you to spend most of your fasting hours asleep
• gives you the flexibility to choose your own eating window
• means you don’t have to count calories 

then give 16:8 fasting a whirl. Choose the 8-hour window that feels right for you as a starting point, decide which day you’ll begin, and go for it! Or, to keep things even more simple, use the Simple app, and we’ll walk you through the process.

I’m not sure, Simple … help me figure it out.

If intermittent fasting has caught your imagination, but you’re wondering if another schedule would suit you better, we’ve got you. Let’s look at some other options. 

Intermittent fasting 16:8 vs. 18:6 (and other time-restricted eating windows).

Perhaps a shorter or longer fast sounds more like you. If so, why not try one of these options:

• 12:12
• 14:10
• 15:9
• 18:6

Which would fit your lifestyle best? 

It’s also worth flagging that we generally don’t recommend fasting for 18+ hours without approval (and supervision) from your healthcare provider. So, if you’re thinking of trying an 18:6 schedule, make sure to run it by them first.

Intermittent fasting 16:8 vs 5:2 fasting

5:2 fasting means eating as you typically would five days a week and practicing a modified fast — where you reduce your intake to 500–600 calories — on the other two days. 

5:2 arguably requires less effort than 16:8 fasting as you’re not fasting every day, and the 5:2 structure may work better with your family, social, and work life. 

However, the fasting periods are longer, and hunger could be a bigger issue. You also need to count calories on your fast days, which adds complexity. 

At Simple, we don’t recommend a restrictive fasting schedule like this one where you eat either nothing or a limited amount of calories for 18+ hours — they involve more potential risks and safety concerns. Plus, while there’s some research that suggests this type of fasting may be more beneficial for lowering cholesterol, there isn’t really evidence to suggest it’s more effective in terms of other results (like weight loss, reduced blood pressure, and better glycemic control) than time-restricted eating (our most recommended approach).[17] But, if you think it might suit you well, talk it over with your doctor.

Intermittent fasting 16:8 vs. alternate-day fasting (ADF).

With ADF, you fast every other day and eat as you typically would on the days between. Again, you’re not fasting every day, which might fit your lifestyle better. Then again, the fasting periods are longer, and hunger can be a real challenge — and as we mentioned above, we don’t recommend more restrictive fasts without a doctor’s seal of approval.

Intermittent fasting 16:8 vs. one meal a day (OMAD).

OMAD requires you to fast for 23 hours and eat all your nutrients in a one-hour window. You can schedule your eating window any time that works for you, but it’s very restrictive overall, and we really wouldn’t recommend it unless you have the approval and support of your healthcare team. Otherwise you’re putting yourself at much higher risk for side effects like nutrient deficiencies, fatigue, tummy troubles, and Hangry Hunger Hulk tendencies. 

Intermittent fasting 16:8 vs. water fasting. 

A water fast — where you only consume water for 24 to 72 hours — is a short-term option. Apart from safety concerns around its high levels of restriction, it might also only yield short-term results.[18] However, if you think it may suit your goals, consult your healthcare team and ensure you have safety protocols in place.

It’s your call whether the 16:8 intermittent fasting schedule is right for you.

If, after all that, you’re still side-eyeing the screen in a, “I might like this, but I’m not sure” way, no worries. Our suggestion:

Just try it for a couple of days. 

There are no binding decisions here. Simply dip a toe in the water and see if you like it.

Written by Trey Reck

Medically reviewed by Josie Porter, RD

Published on | Updated on June 10, 2024