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16:8 Is The Science-Backed & Super-Approachable Way To Intermittent Fast

Allison Young
Author: Expert reviewer:
Updated on June 10, 2022
Allison Young
By Allison Young
mbg Contributor
Allison Young is a freelance writer based out of Phoenix. She writes about health, fitness, travel and relationships.
Molly Knudsen, M.S., RDN
Expert review by
Molly Knudsen, M.S., RDN
Registered Dietitian Nutritionist
Molly Knudsen, M.S., RDN is a Registered Dietician Nutritionist with a bachelor’s degree in nutrition from Texas Christian University and a master’s in nutrition interventions, communication, and behavior change from Tufts University. She lives in Newport Beach, California, and enjoys connecting people to the food they eat and how it influences health and wellbeing.

Intermittent fasting is an eating schedule on which you go without food for a certain amount of time. And given the slew of benefits (think weight loss, blood sugar control, and even longevity), it may not be a question of whether you should try intermittent fasting but rather which type of intermittent fasting to try.

There's the 5:2 model (eat normal calories five days a week and only 500 calories the other two days); alternate-day fasting (one day you eat normally, the next you eat very little); OMAD (as in "one meal a day"); and then there's 16:8 fasting, which limits food to an eight-hour eating window each day.

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If you are new to fasting, you probably want to start with 16:8, proponents plug its built-in flexibility and ease to follow.

What is 16:8 intermittent fasting?

The 16:8 fasting plan is an eating schedule in which you fast for 16 hours each day and eat during an eight-hour window.

This eating schedule comes with all the benefits of other fasting schedules (plus, recent research finds that it may lower blood pressure). Perhaps even better, you pick the eating window.

So what should that eating window be? "There's actually infinite variability. It can be any time. Any time that you don't eat—that's fasting," explains Jason Fung, M.D., fasting expert and author of the book The Complete Guide to Fasting.

If you can't live without breakfast, slot your food earlier in the day (8 a.m. to 4 p.m.).

If you prefer an early dinner, eat in the middle of the day (11 a.m. to 6 p.m.).

If you're someone who regularly goes out with friends for late dinners, schedule your eating hours later in the day (1 p.m. to 9 p.m.).

Contrary to popular opinion, there are no rules around how many meals you have to squeeze in or whether or not you have to include breakfast. In fact, no data actually proves breakfast makes you healthier or weigh less.

Summary

The 16:8 fasting plan is an eating schedule in which you fast for 16 hours each day and eat during an eight-hour window.
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How to get started

Once you decide on a general eating window and talk to a professional to make sure IF is right for you, it's time to jump in—but not necessarily all in.

“I suggest starting with a 12-hour daily fast and easing into a 16-hour fast," says Vincent Pedre, M.D., a functional medicine physician and gut health expert who often recommends IF to his patients. "Leave alternate-day and 20-hour fasts to people who've done it for a while.”

Some experts suggest starting just a couple of days a week and working your way up, while others recommend gradually increasing your fasting window from 12 to 14 to 16 hours. "It's important to listen to your body," Pedre adds.

Even though food is off-limits during fasting hours, non-caloric drinks and exercise are not. Research says they could even stave off hunger.

For liquids, that includes water, black coffee, and unsweetened tea (just skip the cream and sugar).

What's more, exercising in a fasted state can supercharge your body's fat-burning potential—but again, listen to your body. "If you feel too weak to work out from fasting, then you should take care of your nutrition and work out later,” Pedre cautions.

Summary

Experts recommend easing into a 16-hour fast. Start with just a couple of days a week and work your way up. Non-caloric drinks like water, black coffee, and unsweetened tea may help stave off hunger.
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Meal plans

Now for the food. Yes, 16:8 fasting gives you the freedom to consume what you want during the eating window, but it's not an excuse to go pancake-pizza-Pringles wild.

"During your periods of eating, you need to stick with a clean, whole foods diet," says functional medicine expert Will Cole, D.C., IFMCP, "Since some of the benefits of fasting include reduced inflammation, loading up on junk food during your eating window can perpetuate this inflammation. And with inflammation being the underlying contributing factor in almost all modern-day health problems, this is something you definitely want to keep under control."

That means yes to clean proteins, healthy fats, and carbohydrates from whole food sources.

Skip the ultraprocessed foods and drive-thru; just don't skip the focus on delicious. With less time spent on food prep and planning, it may even make you more creative in the kitchen.

Here's an idea of what to eat (and when to eat it) on a 16:8 fasting diet, depending on which eating window you choose:

Early eating window meal plan

  • 8 a.m.: egg and veggie scramble, side of whole-grain toast
  • 10 a.m.: yogurt and granola
  • 12 p.m.: chicken and veggie stir fry
  • Evening decaf tea
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Midday eating window meal plan

Late eating window meal plan

  • Morning black coffee or tea (no cream or sugar)
  • 1 p.m.: blackberry chia pudding
  • 4 p.m.: black bean quesadilla (cheese of your choice, black beans, bell pepper, and taco seasoning)
  • 6 p.m.: banana 
  • 9 p.m.: grilled salmon, vegetables, and quinoa

Summary

Stick to clean proteins, healthy fats, and carbohydrates from whole food sources. Avoid ultraprocessed and fast food.
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Safety and side effects

Intermittent fasting has been associated with a variety of promising science-baked perks, however, like most diets and regimens, it isn't for everyone.

Experts recommend you ease into fasting and as always, speak with your doctor to determine the right plan for you.

If you are pregnant or breast feeding, avoid fasting altogether as fasting promotes fat burning and fat is essential for pregnant women. It can also lead to reduced milk supply and inadequate nutrient intake for both mom and baby.

Additionally, if you have a history of an eating disorder, you should also avoid fasting as it can be triggering for anyone with a history of eating disorders.

According to board-certified internist Vincent M. Pedre, if you have gut issues, food sensitivities, sleep disturbances, anxiety, or chronic stress, fasting can sometimes trigger your fight-or-flight response, which may exacerbate these issues.

Summary

Ease into fasting to avoid any potential side effects. If you are pregnant or beast feeding, or have a history of an eating disorder, avoid fasting all together.

The takeaway

If you've decided to give intermittent fasting a try, the 16:8 fasting plan is a great beginner-friendly option.

To ensure it's right for you, start with just a couple of days a week and work your way up. Be sure to listen to your body, though. If you feel lightheaded or weak, or you feel like fasting is impairing your day-to-day activities, always eat something.

As always, consult your doctor to determine the right plan for you.

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Allison Young
Allison Young

Allison Young is a freelance writer based out of Phoenix. She writes about health, fitness, travel and relationships for leading women's and lifestyle brands like Women's Health, Good Housekeeping, Prevention, and more.