Why Intermittent Fasting Works
Intermittent Fasting (IF) Many diets focus on what to eat, but intermittent fasting is all about when you eat.
With intermittent fasting, you only eat during a specific time. Research shows fasting for a certain number of hours each day or eating just one meal a couple days a week may have health benefits.
Johns Hopkins neuroscientist Mark Mattson has studied intermittent fasting for 25 years. He says our bodies have evolved to be able to go without food for many hours, or even several days or longer. In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive — and thrive — for long periods without eating. They had to: It took a lot of time and energy to hunt game and gather nuts and berries.
Experts note that even 50 years ago, it was easier to maintain a healthy weight in the United States. There were no computers, and TV shows turned off at 11 p.m.; people stopped eating because they went to bed. Portions were much smaller. More people worked and played outside and, in general, got more exercise.
With internet, TV and other entertainment available 24/7, many adults and children stay awake for longer hours to watch TV, scroll through social media, play games and chat online. That can mean sitting and snacking all day — and most of the night.
Intermittent Fasting can do more than slim just your waistline. Studies show that the benefits of fasting include helping stabilize blood sugar levels, reduce inflammation, and keep your heart and even your brain healthy. There are a variety of approaches to intermittent fasting, whether you prefer to fast for a good chunk of hours each day or skip meals for two days each week. Let's look below at how intermittent fasting can serve as one way to simultaneously improve your health and achieve your weight loss goals. Consider this your intermittent fasting beginner's guide.
What Is Intermittent Fasting? Intermittent fasting, also known as cyclic fasting, has risen in popularity in recent years as more research emerges showing that it's typically safe and effective. However, intermittent fasting is hardly a new concept. It's been used for centuries during times when food was scarce, and it even plays a central role in many major religions. In a 2016 Cell Metabolism study, the authors discuss how fasting allows humans to rely less on our glucose (sugar) stores for energy and instead on our ketone bodies and fat stores (keto intermittent fasting). As a result, “both intermittent and periodic fasting result in benefits ranging from prevention to the enhanced treatment of diseases.” It's difficult to define intermittent fasting, as there's not just one method for how to fast. In fact, there are many different variations that are used around the world. Each follows a different eating pattern that is often strictly adhered to in order to achieve physical or even spiritual results.
How Does Intermittent Fasting Work? The extensive research on the concept of intermittent fasting suggests it functions in two different ways to improve various facets of health: First, intermittent fasting results in lowered levels of oxidative stress to cells throughout the body. Second, fasting improves your body's ability to deal with stress at a cellular level. It activates cellular stress response pathways similar to very mild stressors, acting as a mild stimulant for your body's stress response. As this occurs consistently, your body is slowly reinforced against cellular stress and is then less susceptible to cellular aging and disease development.
Common Types of Intermittent Fasting:
- Alternate-Day Fasting: This entails eating every other day. On fasting days, some eat no food at all, and others eat a very small amount, typically around 500 calories. On non-fasting calorie days, eat normally (but healthfully).
- The Warrior Diet: This diet involves eating only fruits and vegetables during the day and then eating one large meal at night.
- 16:8 Fasting: (also often referred to as Time-Restricted Feeding) For this method, you fast for 16 hours every day and limit your eating to eight hours. Most often, a key component of 16/8 intermittent fasting is skipping breakfast. This approach involves not eating anything after dinner and skipping breakfast the next morning.
- Eat-Stop-Eat: Practice the “Eat Stop Eat” method by picking one or two days out of the week in which you fast for 24 hours, then eat nothing from dinner one day until dinner the next day. On the other days, you should have normal calorie days.
- 5:2 Diet: For five days of the week, you eat normally. For the remaining two fast days, you should restrict your caloric intake to between 500–600 calories every day.
- 42-hour: (and beyond) When you combine the 18:6 with a 36-hour fast, you get a 42-hour fasting period. For example, you would eat dinner at 6 pm on day 1. You skip all meals on day 2 and eat your regular ‘break fast’ meal at 12:00. This is a total of 42 hours.