What's the Deal with Intermittent Fasting?
By English Taylor
There’s nothing intermittent about how often we hear about intermittent fasting. According to Bloomberg, monthly Google searches for “intermittent fasting” have risen tenfold over the past three years—to as many as one million. (That’s about as many searches as “weight loss” receives,and even more than “diet.”) Fasting is defined by Britannica as, “abstinence from food or drink or both for health, ritualistic, religious, or ethical purposes. The abstention may be complete or partial, lengthy, of short duration, or intermittent.”
Fasting has been practiced by followers of religions and individuals or groups as a form of protest against violations of social, ethical, or political rights since ancient times. Today, celebrities and health enthusiasts also rely on intermittent fasting to maintain optimal wellness and feel their best. Given fasting’s deep historical roots, can its role as a dietary tool also stand the test of time? We turned to an expert to learn why intermittent fasting isn’t just another fad.
What is intermittent fasting?
Dr. Jason Fung founded the Intensive Dietary Management program (IDM), which relies on the use of intermittent and extended fasting to treat weight issues and metabolic conditions like type 2 diabetes and polycystic ovarian syndrome (PCOS). We first learned about Dr. Fung and fasting on Balanced Bites, one of our favorite wellness podcasts by certified nutrition consultants Diane SanFilippo and Liz Wolfe.
“Intermittent fasting is the ancient secret of health,” writes Dr. Fung in this “Intermittent Fasting for Beginners” guide. “It is ancient because it has been practiced throughout all of human history. It’s a secret because this powerful habit has been virtually forgotten. But now many people are re-discovering this dietary intervention. It can carry huge benefits if it is done right: weight loss, increased energy, reversal of type 2 diabetes, and many other things.”
Some people immediately equate fasting with starvation, which isn’t the case. Dr. Fung explains that intermittent fasting is the voluntary absence of food, which is how it differs from starvation. In other words, you choose not to eat. When you define fasting this way, you’re technically fasting anytime you decide not to eat, like between dinner and breakfast the next day. Dr. Fung adds that the word “breakfast” is actually rooted in the act of fasting. It’s the meal that “breaks” the “fast” that has lasted since dinner the previous evening. Cool, right?
How intermittent fasting works
“At its very core, fasting simply allows the body to burn off excess body fat,” says Dr. Fung. “Body fat is merely food energy that has been stored away. If you don’t eat, your body will simply ‘eat’ its own fat for energy.”
Here’s how this works: When we eat, the hormone insulin rises. Insulin helps our body store the excess energy (food) in the liver as glycogen and in other places in the body as fat.
Now, imagine this process in reverse. When we don’t have energy (food) entering the body, insulin levels drop. This signals our body to rely on and burn stored energy, since nothing is coming in through food. Thus, our body turns to the stored glycogen and body fat as energy. As Dr. Fung explains, “The body only really exists in two states—the fed, insulin-high state and the fasting, insulin-low state. Either way, we are storing food energy or we are burning it. If eating and fasting are balanced, then there is no net weight gain.”
Is it just us, or does anyone notice that they don’t stop eating from the minute they roll out of bed? It’s snack after snack after snack. Plus, we’re always reading about the benefits of eating six small meals a day. But when we’re always eating, we don’t allow our insulin levels to drop and our body to burn stored fat. “If you are constantly eating, as is often recommended, then your body will simply use the incoming food energy and never burn the body fat,” says Dr. Fung. “You’ll only store it. Your body will save it for a time when there is nothing to eat.” So, to restore balance or lose weight, we need to increase the amount of time we burn fat through fasting.
The benefits of intermittent fasting
Dr. Fung says that fasting’s most obvious benefit is weight loss. However, there are a myriad of benefits beyond this, like:
Improved mental clarity and concentration
Lowered blood insulin and sugar levels
Reversal of type 2 diabetes
Lowered blood cholesterol
Reduction of inflammation
How to try intermittent fasting
There are great resources for those new to intermittent fasting like Dr. Fung’s book The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting. The previously cited guide is full of helpful tips, too.
Since we’re all about balance, we’re planning to start out with a shorter fast that lasts less than 24 hours, like the 16:8 fast. “This involves daily fasting for 16 hours,” says Dr. Fung. “Sometimes this is also referred to as an eight-hour eating ‘window.’ You eat all of your meals within an eight-hour time period and fast for the remaining 16 hours. Generally, this is done daily or almost daily.” For example, you may eat all of your meals within the time period of 10am and 6pm, and fast from 6pm until 10am the next day.
We’re planning to begin by fasting a few days a week, just to see how we feel. From there, perhaps we’ll start fasting Monday through Friday. (We love our late-night pizza on the weekends. Everything in moderation, right?)
Hold up, not so fast (pun intended): Before you try fasting, we recommend checking in with a medical professional, especially if you’re a kid or teenager who’s still growing, pregnant, or breastfeeding. After all, everyone’s body and health needs are different. Regardless of whether you try intermittent fasting or not, it’s always fascinating to learn about the latest and greatest trends in the health world—even if the “trend” has been around for ages.