Want To Try Intermittent Fasting? This Method Is Science-Backed & Super Approachable (2024)

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December 28, 2022

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Aja Gyimah, R.D.

Registered dietitian

Aja Gyimah is a registered dietitian with a passion for teaching people how to use food to live healthier lives

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The takeaway

December 28, 2022

Intermittent fasting is an eating schedule on which you go without food for a certain amount of time. And depending on your goals (think weight management) and lifestyle habits, it may not be a questionof 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.

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

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," explainsJason Fung, M.D., fasting expert and author of the bookThe 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 healthier1 or weigh less2.

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.

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," saysVincent Pedre, M.D., a functional medicine physician and gut health expert who often recommends IF to his patients."Leave alternate-day and 20-hour faststo 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 state3 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. It’s typically recommended by RDs to eat a small number of carbohydrates before exercise so you don’t burn out too quickly.

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.

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 to whole foods," 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 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

Midday eating window meal plan

  • Morning: black coffee or tea (no cream or sugar)
  • 11 a.m.: banana peanut butter smoothie
  • 2 p.m.: avocado toast with pistachios
  • 4 p.m.: dark-chocolate-covered almonds
  • 6 p.m.: turkey meatballs and tomato sauce over whole wheat (or zucchini noodle) pasta

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.: bananaand peanut butter or yogurt
  • 9 p.m.: grilled salmon, vegetables, and quinoa

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 breastfeeding, 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.

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 or dietitian to determine the right plan for you.

RELATED STORY: Does Intermittent Fasting Help With Healthy Weight Loss?

Want To Try Intermittent Fasting? This Method Is Science-Backed & Super Approachable (2024)

FAQs

Is there any real science behind intermittent fasting? ›

Studies discovered that intermittent fasting boosts working memory in animals and verbal memory in adult humans. Heart health. Intermittent fasting improved blood pressure and resting heart rates as well as other heart-related measurements.

What is the most effective intermittent fasting method? ›

Depending on your lifestyle and when you can manage to stop eating, the best hours for intermittent fasting include the 16/8 or 14/10 fasting periods. Intermittent fasting is hailed by many as the new mantra of weight loss, disease prevention, and reversal of aging.

What are the negatives of intermittent fasting? ›

As much as IF is filled with benefits, there are mild side effects that can happen during fasting, which do not generally require medical or surgical treatment. Possible side effects can include dizziness, nausea, insomnia, headache, weakness, etc.

What is the trick to intermittent fasting? ›

The easiest way to do the 12-hour fast is to include the period of sleep in the fasting window. For example, a person could choose to fast between 7 p.m. and 7 a.m. They would need to finish their dinner before 7 p.m. and wait until 7 a.m. to eat breakfast but would be asleep for much of the time in between.

Do doctors recommend intermittent fasting? ›

Intermittent fasting is safe for many people, but it's not for everyone. Skipping meals may not be the best way to manage your weight if you're pregnant or breast-feeding. If you have kidney stones, gastroesophageal reflux, diabetes or other medical problems, talk with your doctor before starting intermittent fasting.

What happens after 1 month of intermittent fasting? ›

The 20/4 fasting method is linked with cardiovascular improvements, such as reduced blood pressure and cholesterol levels. These changes directly contribute to a lower risk of developing heart disease, strokes, and other cardiovascular conditions, underscoring the heart health benefits of this fasting regimen.

How much weight can you lose in a month with intermittent fasting? ›

If you consistently stay active while following intermittent fasting, you can lose as much as 6-8 pounds per month. This estimation is shockingly high when you consider that all you have to do is not eat for select hours throughout the day.

What is the best intermittent fasting window to lose belly fat? ›

A 2023 review of research found that the 16/8 method and 16/8 combined with restricting calories were effective strategies for weight control in adults with overweight or obesity. An eating window starting before noon led to greater weight loss than one that began after noon.

Why am I gaining weight with intermittent fasting? ›

Intermittent fasting itself doesn't directly cause weight gain. Gaining weight while fasting usually comes from overeating, low protein intake, and/or too much caffeine. Eating nutrient-rich food, drinking water, and being active can help us avoid gaining weight with intermittent fasting.

Can intermittent fasting reduce belly fat? ›

Belly fat, also known as visceral fat, is not only unsightly, but also leads to many health risks, such as diabetes, heart disease or obesity. Many people choose intermittent fasting to reduce their excess belly fat.

Is it bad to intermittent fast everyday? ›

Intermittent fasting can be dangerous if taken too far. A technique called dry fasting restricts food and fluid intake, resulting in severe dehydration and posing serious health concerns. Malnutrition can occur if the caloric restriction is too severe, such as averaging fewer than 1,200 calories a day long term.

Why is 16 hours the magic number for fasting? ›

While both 12-hour and 16-hour fasting can promote fat burning, it's possible that a 16-hour fast may be more effective. This is because the longer fasting period may lead to a greater depletion of glycogen stores, which can trigger higher levels of fat burning.

Does lemon water break a fast? ›

Flavor without Breaking Fast: One of the challenges of fasting is the boredom of consuming plain water only. Adding True Lemon adds a refreshing twist without adding calories, which means it won't break your fast.

Why am I not losing weight on 16:8 fasting? ›

If you've tried intermittent fasting but aren't losing weight, possible reasons why include overeating during your eating window and poor food choices. To help, you can try eating fewer calories, work on balancing your meals, or create a smaller or larger eating window.

Does coffee break a fast? ›

Technically speaking, eating or drinking any calories breaks a fast. That means it's generally considered OK to drink black, unsweetened coffee or tea, as well as water.

What is the science behind intermittent fasting and weight loss? ›

One of the key mechanisms of intermittent fasting is that it can alter the hormones that control hunger and fat storage. During fasting periods, insulin levels drop and allow the body to access stored fat for energy. This shift in metabolism promotes fat-burning and contributes to weight loss over time.

Is it better to fast 12 or 16 hours? ›

A good rule of thumb for those wanting to fast to improve their metabolic and overall health is to leave at least 12 hours between meals – ideally more – on a regular basis, according to Dr Adam Collins, Principal Teaching Fellow in Nutrition at the University of Surrey.

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