Intermittent fasting is the newest healthy eating craze. But the unique aspect of this diet is that you keep track of when you eat, not how much. In fact, it’s technically not a “diet,” since you can eat whatever you want when you’re not fasting. Yet, people that take part in this style of eating often lose weight (1). And studies suggest that intermittent fasting may help you live longer (2) and even prevent Alzheimer’s disease (3).
So, What Exactly Is Intermittent Fasting?
Intermittent fasting is a method of eating that involves abstaining from food for a set amount of time. The fasting periods can range from 12 hours to a full day. Because your body has a break from actively digesting food, your body can burn more fat during the fasting portion.
The dietary approach dates back centuries but became trendy recently. “Many religions fast for various reasons and have been doing so for years,” says registered dietitian Amanda Barnes. “Intermittent fasting gained popularity in 2012 with the book The Fast Diet by Michael Mosley. The book touted that fasting two non-consecutive days per week leads to weight loss and other benefits.”
3 Intermittent Fasting Methods to Try
According to Barnes, there are three different ways to approach intermittent fasting:
- Alternate day fasting or 5:2: You eat whatever you want five days per week, but don’t consume any calories two non-consecutive days per week.
- Modified fasting: Similar to the 5:2 method, you can eat whatever you want five days per week. On the other two days, you can take in 20 to 25 percent of your daily caloric needs (approximately 400 to 600 calories).
- Time-restricted fasting: You fast between 12 to 18 hours per day, but can eat whatever you want during your non-fasting time. Many people skip breakfast and then eat between the hours of 11 a.m. and 7 p.m. every day.
What Intermittent Fasting Enthusiasts Love About It
If people you know eat this way, you’ll know about it. Let’s just say people who practice intermittent fasting tend to become devoted to this method of eating. It’s like the CrossFit of nutrition plans. Here’s what intermittent fasting fans love about it:
- Weight loss: Studies consistently show that fasting leads to weight loss, although Barnes points out that most studies on intermittent fasting have been small (usually 100 participants or less). “If you’re skipping meals or eliminating a day of calories overall throughout the week, you’ll consume fewer calories, which will naturally lead to weight loss,” says Barnes.
- Lack of meal prep: Most methods of eating healthfully include some form of meal prep or planning. With the time-restricted method of intermittent fasting, you’re eating one less meal per day. That’s one less meal to think about, shop for or prepare.
- No forbidden foods: Unlike other popular diets, no foods are off-limits, and you don’t count calories. You can eat socially, drink cocktails and have dessert (as long as it’s during your eating window, of course).
How to Practice Intermittent Fasting
Before starting any new eating pattern, it’s important to talk to your doctor and make sure it’s safe for you. And certain people should avoid intermittent fasting entirely. “Fasting can affect blood sugar levels and leave certain populations more at risk. If you’re pregnant, have any health conditions, especially diabetes, heart conditions or are prone to low blood sugar, this diet is risky,” says Barnes. She also recommends that people who take medications (especially those that need to be consumed with food) consult with a doctor before attempting intermittent fasting. “And anyone with disordered eating should avoid following any strict diet, intermittent fasting included,” adds Barnes.
Once your health care provider gives you the go-ahead, here’s how to start:
- Pick the method that works best for you. Look at your current schedule and eating habits to decide which strategy fits into your life. Do you have some jam-packed work days where you barely have time to eat? Maybe you try the modified fasting method (where you eat limited calories two days per week). If you’re never in the mood for breakfast, you might want to try the time-restricted approach, and only eat in the afternoon and early evening. Start with the system you think will work best, but don’t worry, you can switch to another method if it’s not sustainable for you.
- Know the obsessive food thoughts will pass. Many newbies to this eating style admit that the first few days can be rough and fantasizing about food is common. But by a week into intermittent fasting, hunger pangs should subside, your energy levels should be consistent and you’ll have a better idea of whether this eating style is something you’ll want to stick with.
- Take it slow exercise-wise: Most people who practice intermittent fasting work out regularly. “You might feel hungry after a workout, so it might not be enjoyable to do it on a full fasting day. Walking, yoga and stretching might be better on fasting days to avoid any negative side effects,” says Barnes. If you do time-restricted fasting, it might be best to save your exercise session for right before you break your fast for the day.
- Don’t forget to drink up: It’s important to stay hydrated while fasting, so even though you’re not eating, keep your water bottle handy. And during fasting times, you’re allowed to have tea or black coffee. “Keep in mind that caffeine can have greater effects on an empty stomach, so you might be more prone to shaking or anxiety if you consume too much. Again, listen to your body and how it’s feeling with a new routine.”