Source: The Beginner’s Guide to Intermittent Fasting, By: James Clear
What is Intermittent Fasting and Why Would You Do It?
Intermittent fasting is not a diet, it’s a pattern of eating. It’s a way of scheduling your meals so that you get the most out of them. Intermittent fasting doesn’t change what you eat, it changes when you eat.
Why is it worthwhile to change when you’re eating?
Well, most notably, it’s a great way to get lean without going on a crazy diet or cutting your calories down to nothing. In fact, most of the time you’ll try to keep your calories the same when you start intermittent fasting. (Most people eat bigger meals during a shorter time frame.) Additionally, intermittent fasting is a good way to keep muscle mass on while getting lean.
With all that said, the main reason people try intermittent fasting is to lose fat. We’ll talk about how intermittent fasting leads to fat loss in a moment.
Perhaps most importantly, intermittent fasting is one of the simplest strategies we have for taking bad weight off while keeping good weight on because it requires very little behavior change. This is a very good thing because it means intermittent fasting falls into the category of “simple enough that you’ll actually do it, but meaningful enough that it will actually make a difference.”
How Does Intermittent Fasting Work?
To understand how intermittent fasting leads to fat loss we first need to understand the difference between the fed state and the fasted state.
Your body is in the fed state when it is digesting and absorbing food. Typically, the fed state starts when you begin eating and lasts for three to five hours as your body digests and absorbs the food you just ate. When you are in the fed state, it’s very hard for your body to burn fat because your insulin levels are high.
After that timespan, your body goes into what is known as the post–absorptive state, which is just a fancy way of saying that your body isn’t processing a meal. The post–absorptive state lasts until 8 to 12 hours after your last meal, which is when you enter the fasted state. It is much easier for you body to burn fat in the fasted state because your insulin levels are low.
When you’re in the fasted state your body can burn fat that has been inaccessible during the fed state.
Because we don’t enter the fasted state until 12 hours after our last meal, it’s rare that our bodies are in this fat burning state. This is one of the reasons why many people who start intermittent fasting will lose fat without changing what they eat, how much they eat, or how often they exercise. Fasting puts your body in a fat burning state that you rarely make it to during a normal eating schedule.
The Benefits of Intermittent Fasting
Fat loss is great, but it isn’t the only reason to try intermittent fasting.
1. Intermittent fasting makes your day simpler.
I’m big on behavior change, simplicity, and reducing stress. Intermittent fasting provides additional simplicity to my life that I really enjoy. When I wake up, I don’t worry about breakfast. I just grab a glass of water and start my day.
I enjoy eating and I don’t mind cooking, so eating three meals a day was never a hassle for me. However, intermittent fasting allows me to eat one less meal, which also means planning one less meal, cooking one less meal, and stressing about one less meal. It makes life a bit simpler and I like that.
2. Intermittent fasting helps you live longer.
Scientists have long known that restricting calories is a way of lengthening life. From a logical standpoint, this makes sense. When you’re starving, your body finds ways to extend your life.
There’s just one problem: who wants to starve themselves in the name of living longer?
I don’t know about you, but I’m interested in enjoying a long life. Starving myself doesn’t sound that appetizing.
The good news is that intermittent fasting activates many of the same mechanisms for extending life as calorie restriction. In other words, you get the benefits of a longer life without the hassle of starving.
Way back in 1945 it was discovered that intermittent fasting extended life in mice. (Here’s the study.) More recently, this study found that alternate day intermittent fasting led to longer lifespans.
3. Intermittent fasting may reduce the risk of cancer.
This one is up for debate because there hasn’t been a lot of research and experimentation done on the relationship between cancer and fasting. Early reports, however, look positive.
This study of 10 cancer patients suggests that the side effects of chemotherapy may be diminished by fasting before treatment. This finding is also supported by another study which used alternate day fasting with cancer patients and concluded that fasting before chemotherapy would result in better cure rates and fewer deaths.
Finally, this comprehensive analysis of many studies on fasting and disease has concluded that fasting appears to not only reduce the risk of cancer, but also cardiovascular disease.
4. Intermittent fasting is much easier than dieting.
The reason most diets fail isn’t because we switch to the wrong foods, it’s because we don’t actually follow the diet over the long term. It’s not a nutrition problem, it’s a behavior change problem.
This is where intermittent fasting shines because it’s remarkably easy to implement once you get over the idea that you need to eat all the time. For example, this study found that intermittent fasting was an effective strategy for weight loss in obese adults and concluded that “subjects quickly adapt” to an intermittent fasting routine.
I like the quote below from Dr. Michael Eades, who has tried intermittent fasting himself, on the difference between trying a diet and trying intermittent fasting.
Diets are easy in the contemplation, difficult in the execution. Intermittent fasting is just the opposite — it’s difficult in the contemplation but easy in the execution.
Most of us have contemplated going on a diet. When we find a diet that appeals to us, it seems as if it will be a breeze to do. But when we get into the nitty gritty of it, it becomes tough. For example, I stay on a low–carb diet almost all the time. But if I think about going on a low–fat diet, it looks easy. I think about bagels, whole wheat bread and jelly, mashed potatoes, corn, bananas by the dozen, etc. — all of which sound appealing. But were I to embark on such a low–fat diet I would soon tire of it and wish I could have meat and eggs. So a diet is easy in contemplation, but not so easy in the long–term execution.
Intermittent fasting is hard in the contemplation, of that there is no doubt. “You go without food for 24 hours?” people would ask, incredulously when we explained what we were doing. “I could never do that.” But once started, it’s a snap. No worries about what and where to eat for one or two out of the three meals per day. It’s a great liberation. Your food expenditures plummet. And you’re not particularly hungry. … Although it’s tough to overcome the idea of going without food, once you begin the regimen, nothing could be easier.
— Dr. Michael Eades
In my opinion, the ease of intermittent fasting is best reason to give it a try. It provides a wide range of health benefits without requiring a massive lifestyle change.