If you're thinking of losing weight, you've probably heard of intermittent fasting, which has been gaining in both popularity and general acceptance from health professionals. For those of you who don't know, intermittent fasting is a diet method that cycles between periods of eating and fasting as a means of restricting overall calorie intake. With intermittent fasting, it's not so much about what you eat, but when you eat. Hardcore believers maintain that intermittent fasting has benefits beyond weight loss, including everything from minimizing the risk of diabetes to more grandiose claims like enabling you to live a longer life.
But is it worth the potential downsides? And will you ever stop feeling "hangry"? Here's everything you need to know before deciding whether the intermittent fasting diet is for you.
Different types of intermittent fasting
This is the easiest method of intermittent fasting, and a great option for beginners who want to ease in to a more rigorous fast. The 12/12 method means you only eat within a 12-hour period (say 8 am to 8 pm), and avoid eating the remaining 12 hours of the day. The great part about this plan is that you will likely be sleeping for most of those 12 hours, and if your weakness is snacking late at night, the 12/12 method is a simple change you can make to cut unnecessary calories without necessarily having to track your overall calorie consumption. There are different iterations of this method that you can work up to. Once you've mastered the 12/12 method, you may want to consider the 16/8 method (fast for 16 hours, eat within an 8-hour period), and, once you're a pro, the 20/4 method (fast for 20 hours, eat within a 4-hour period).
This is a diet that has been gaining traction, thanks to books like The Fast Diet. For the 5:2 diet you restrict your calorie intake to only 25% of your normal intake for part of the week. So, if you normally consume 2,000 calories a day, for two days a week you would restrict your intake to just 500 calories, which would amount to a few (very) small snacks or one large meal for the entire day. The other five days you would eat as you normally would. The idea behind this diet is that overall, you will consume fewer calories over the course of a week than you would on other diets. The diet also claims that it is in fact healthier for your body to abstain from food temporarily, as it gives your cells time to repair. The most important idea underlying this diet, though, is that it will change your relationship to hunger and release life-long dieters from calorie counting and the anxiety around the ever-persistent question, "what should I eat?"
Another version of this diet, Eat-Stop-Eat, involves a complete 24-hour fast 1-2 days a week. This is a more extreme version of intermittent fasting that is probably best approached gradually, once you are confident that you can go long stretches of time without eating.
Benefits of intermittent fasting
Unless you're binging on non-fasting days, intermittent fasting will necessarily lead to a reduction in calorie consumption. Compared to other popular diets, like the Whole 30, some studies have found that intermittent fasting has an advantage when it comes to weight loss and minimizing weight gain after an extended period of time.
A second benefit is that intermittent fasting could significantly change your relationship to food, which is especially meaningful if your relationship, like many dieters', is fraught. With intermittent fasting, you need to be comfortable with being hungry, and realize that you will be OKAY if you don't eat three square meals a day. Some have claimed that intermittent fasting can even help restore unhealthy relationships with food, including obsessive calorie counting that often leads to a complete disconnection between eating and actual hunger.
There are also many who claim that intermittent fasting can reduce the risk of diabetes, since restrictive eating has been shown to lower insulin levels, and some forms of cancer. Another potential benefit to consider is greater mental acuity; a study by the NIH has found that restricted eating may improve the function of nerve cells.
Downsides of intermittent fasting
You will be hungry, and hunger can be very unpleasant. For some, hunger can be a serious distraction that could get in the way of daily life. Still, hunger is something you'll probably be able to overcome; and there are still other, more serious downsides to consider.
The first is that this may not be the diet for you if you have a history of disordered eating, even though the diet can restore an unhealthy relationship with food. It is far too easy to go to extremes with intermittent fasting. The second issue is that while intermittent fasting is generally very effective for those who stick to their plan, there is a very high drop-out rate—38% to be exact. For some, dramatic restrictions on calorie intake are just not reasonable, especially for those who exercise intensely or 4 or more days a week or who already have insulin issues.
So, should I try it?
Intermittent fasting can be a very effective way to lose weight, and perhaps even change your relationship to food and how you experience hunger in the long run, even if you don't end up sticking to the diet in a strict sense for an extended period of time.
If you do decide to try intermittent fasting, be sure to approach the diet gradually. For example, start with the 12/12 or 16/8 method before going on to the 20/4 method, or begin by simply restricting calories on the 5:2 diet before going for the 24-hour fast. This will help you achieve greater success, and will lessen the likelihood that you'll drop out. Also consider the days you choose to fast; pick days on which you are busy (boredom and hunger do go hand-in-hand) but do not have social events to make your fast a little more bearable.
Of course, as with any other major change to your physical health, you should consult your general practitioner before getting started, to be sure that intermittent fasting is a safe and viable option for you.