There’s no doubt that you’ve heard the term “intermittent fasting” being thrown around by now, whether you understand exactly what the term means or not. It’s been a hot topic in health and wellness circles for over a decade—meaning that it’s no fad and has secured its spot as one of the many lifestyle paths to choose from—with plenty of science and advocates to back it up.
What is Intermittent Fasting?
Intermittent Fasting (IF) is a popular approach to eating that restricts eating times to a predetermined window within the 24-hour clock. If you start out with what’s called a 12:12 fast, that means you’d eat from 8am to 8pm every day and then from 8pm to 8am, you would switch to fasting. Over time, the goal is to extend the fasting window and reduce the feeding window.
The beauty about IF is that you can gradually progress your fasting style by increasing the intensity as you adjust to fasting, and can try on different styles of fasting to see which one suits you best.
How Did IF Start?
Various approaches to fasting have been practiced around the world by many religions and cultures for centuries but it only truly re-emerged as a “new” approach to healthful eating around 2012 and has taken the health-world by storm. Today, there are more than a half dozen ways to fast from 16:8, 18:6, alternate-day fasting, 5:2 and the OMAD diet.
The Various Ways to IF
There are more than a dozen ways to fast and the style you choose will depend on your tolerance for fasting, your individual schedule and lifestyle. Here the 7 of the most popular IF protocols:
- Time-restricted eating (18:6, 16:8, 14:10 and 12:12)
- The 12-6 Plan: only eat between noon and 6pm
- Alternate-day fasting, where you fast one day and eat normally the next
- One meal a day (OMAD), fast for 23 hours a day and eat for just 1
- Eat Stop Eat, where you abstain from food up to two days in a week
- 5:2 where you eat normally for 5 days and then restrict your caloric intake to around 500 calories for two days
- The Warrior Diet where you eat one main meal, feasting in a four hour window at night, as well as fasting for 20 hours sustained with only small portions of foods such as raw fruits-and-veggies throughout the day
No matter what fasting style you choose, after several hours without eating, a process called metabolic switching kicks in. This is when your body depletes its sugar stores and starts to burn fat for energy, which is how IF works so well for weight loss.
How Much Weight Can You Lose?
The amount of weight you can expect to lose will depend on many individual factors such as age, gender, activity level and lifestyle, but research on IF for weight loss is promising.
In one study, weight loss participants lost an average of about 8.8 pounds after following time-restricted fasting for 12 weeks. In the study, participants fasted for 16 hours and ate for 8.
Another meta analysis of over 40 studies found that intermittent fasting for just 10 weeks led to weight loss averages of seven to 11 pounds.
How to Get Started Safely
Experts generally recommend starting with a 12:12 fast—12 hours fasting, 12-hour eating (e.g.: fast from 8PM to 8AM and eat between 8AM and 8PM). Eat three meals in this window and try to let about 4 hours pass between meals and avoid snacks, if possible.
The goal is to gradually increase your fasting window for a longer fasting period. After several days or a week, move to what’s called a “brunch fast” of 14:10 and then 16:8 intermittent fasting—arguably the most popular IF split. And after that, if you feel like you can still dial up the intensity, try 18:6 intermittent fasting.
Remember that what you eat during the window matters. Eat clean, real food and avoid fast food or junk food even if you think you can “afford it” given the caloric reduction for shortened periods of eating.
Check in with Yourself—and Modify As Needed
Not every day has to be the same on your IF plan. Some days, you’ll be hungrier and will need a longer eating window, while other days, you’ll be able to sustain super-long fasts and may only need a single meal, OMAD-style.
Some days you’ll need to eat something after 12 hours of fasting and other days you may effortlessly stretch to 18. The goal is to adapt your body to fast without going hungry or feeling deprived, but when your body is calling for food, answer the call. Tap into an intuitive way of eating.
Who Shouldn’t Try Intermittent Fasting?
Intermittent Fasting is considered safe for most people but there are some exceptions.
Avoid an intermittent fasting protocol if you:
- Have diabetes or blood sugar problems
- Are on blood pressure or heart-health medication
- Have a history of an eating disorder
- Are underweight or struggling with weight gain
And always check with your doctor before starting any type of fasting regimen.
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