Which Is Best for You?

3. Overnight Fasting

This intermittent fasting approach is the simplest of the bunch. It involves fasting for a 12-hour period every day. For example: Choose to stop eating after dinner by 7 p.m., and then resume eating at 7 a.m. with breakfast the next morning. Autophagy does still happen at the 12-hour mark, though you’ll get more mild cellular benefits, Shemek says. This is the minimum number of fasting hours she recommends.

A benefit of this intermittent fasting method is that it’s easy to implement. Also, you don’t have to skip meals; if anything, all you’re doing is eliminating a bedtime snack (if you ate one to begin with). But this method doesn’t maximize the advantages of fasting. If you’re using intermittent fasting for weight loss, a smaller fasting window means more time to eat, and it may not help you decrease the number of calories you take in.

4. Eat Stop Eat

This intermittent fasting approach was developed by author Brad Pilon in his book Eat Stop Eat: The Shocking Truth That Makes Weight Loss Simple Again. His approach differs from other ones in that he stresses flexibility. Simply put, he emphasizes the idea that fasting is just taking a break from food for a time. You complete one or two 24-hour fasts per week and commit to a resistance training program. “When your fast is over, I want you to pretend that it never happened and eat responsibly. That’s it. Nothing else,” he says on his website.

Eating responsibly refers to going back to a normal way of eating, where you don’t binge because you just fasted, but you also don’t restrict yourself with an extreme diet or eat less than you need. Occasional fasting combined with regular weight training is best for fat loss, Pilon says. By going on one or two 24-hour fasts during the week, you allow yourself to eat a slightly higher number of calories on the other five or six nonfasting days. That, he says, makes it easier and more enjoyable to end the week with a calorie deficit but without feeling as if you had to be on an extreme diet.

With this approach to intermittent fasting, it’s important to remember that not eating for an entire day comes with risks like not meeting important nutrient needs or experiencing symptoms like lightheadedness or lethargy.

5. Whole-Day Fasting

In this intermittent fasting approach, you eat once a day. Some people choose to eat dinner and then not eat again until the next day’s dinner, Shemek explains. With whole-day fasting, the fasting periods are essentially 24 hours (dinner to dinner or lunch to lunch), whereas with 5:2 the fasting period is actually 36 hours. (For example, you eat dinner on Sunday, then “fast” on Monday by eating 500 or 600 calories, and break it with breakfast on Tuesday.)

The advantage of whole-day fasting, if done for weight loss, is that it’s really tough (though not impossible) to eat an entire day’s worth of calories in one sitting. The disadvantage of this approach is that it’s hard to get all the nutrients your body needs to function optimally with just one meal. Not to mention, this approach is tough to stick to. You might get really hungry by the time dinner rolls around, and that can lead you to consume not-so-great, calorie-dense choices. Think about it: When you’re ravenous, you’re not exactly craving broccoli. Many people also drink coffee in excess to get through their hunger, Shemek says, which can have negative effects on your ability to sleep. You may also notice brain fog throughout the day if you’re not eating.

6. Alternate-Day Fasting

7. Choose-Your-Day Fasting

This is more of a choose-your-own-adventure approach to intermittent fasting. You might do the time-restricted fasting (fast for 16 hours, eat for 8, for instance) every other day or once or twice a week, Shemek says. What that means is that Sunday might be a normal day of eating, where you stop eating by 8 p.m.; then you’d resume eating again on Monday at noon. Essentially, it’s like skipping breakfast a few days a week.

This approach may be easily adaptable to your lifestyle and is more “go with the flow,” meaning you can make it work even with a schedule that changes from week to week. But a looser approach may mean milder benefits.