Your Definitive Guide To Fasting

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In 2017, we started hearing more and more chatter about fasting, intermittent fasting, the fasting-mimicking diet, and all of the wonderful health benefits of each. And in mbg's "2018 Wellness Trends to Watch," we predicted that fasting would gain a lot of traction this year as a legitimate intervention for way more than just weight loss—but to fight real diseases that affect the quality of life of millions of people around the world.

There are a lot of people talking about the health benefits of fasting, and that means an internet search is going to yield a LOT of results. This can be overwhelming, especially if you consider yourself a newbie. If you're interested in fasting, you may not know where to start or even if it's the right choice for you, and since it's a blossoming area of study, it's likely that you'll encounter some conflicting advice.

At mbg, we work with leading experts in the field of integrative and functional medicine, and many of them are big fans of fasting. Some of them do it themselves, suggest it to their patients, and others have written books on the topic or developed their own fasting protocols. In other words: We have access to a lot of fasting knowledge. And that's why we wanted to put all that expert knowledge in one place, to answer your most burning fasting questions.

What does it really mean to fast?

Quite literally, fasting means going a period of time without food. According to Jason Fung, M.D., fasting expert and author of the book The Complete Guide to Fasting, when it comes to fasting "there's actually infinite variability. It can be any time. Any time that you don't eat—that's fasting. It's the flip side, the B side of eating. It's really that simple." But it can start to feel complicated the more you think about the logistics: Is fasting the same thing as intermittent fasting? Am I allowed to drink water or other zero-calorie beverages? Is fasting actually safe for humans? If you've asked some of these questions and had a hard time finding answers, don't worry—and read on!

Is fasting just a wellness fad?

At mbg revitalize this year, Dr. Steven Gundry, a renowned cardiologist and author of The Plant Paradox, explained that "Our ancestors didn’t crawl out of their cave and say 'What’s for breakfast?' There wasn’t any refrigerator or even any storage system." In many ways, following fasting protocol re-connects us with the way our ancestors lived before there was food at every single checkout counter.

Have you ever noticed that the first thing you do when you get sick is you stop eating? According to Dr. Fung, this is a totally normal response from the body. "You have a surge in hormones and you lower blood glucose to fight infection. This [fasting] isn't a passing fad: It's a 5,000-year-old fad. All of the mechanisms of fasting are deeply, intrinsically human." If you think fasting is a totally alternative practice, Dr. Carrie Diulus—a surgeon and expert in all things health and nutrition—fasting is something she's used to talking about. "As a surgeon, we fast every single patient before surgery. For people with type 2 diabetes or any kind of insulin resistance, different types of fasting can be helpful in reversing those." In other words: Fasting isn't very "woo-woo" at all.

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Is fasting all about weight loss?

When we think about going periods of time without food, it's easy to assume that weight loss is the primary goal. And it's true, one of the most common goals is to make your metabolism more flexible. This means that your body gets used to switching from burning glucose for fuel to burning fat to provide your body with energy, something it loses practice at when we're eating every three or four hours.

We're finding more and more evidence that we can actually train our bodies to burn more fat, which helps many people break through stubborn weight loss plateaus. Fasting before a workout can even help you improve athletic performance, and many experts suggest ending your fast with a workout. It might surprise you, but you'll likely find that you have more energy for your workout when you've been fasting beforehand. But weight loss and even weight management are just the beginning of the health benefits of fasting.

What are the health benefits of fasting?

If you've read up on fasting, you've likely encountered health benefits that range from killing sugar cravings to improving symptoms of Alzheimer's to helping with autoimmune disease. Here is a list of just some of the suggested benefits:

Fasting is thought to help with the following conditions and many more:

The list goes on and on. But how can one practice possibly do all this? Well, according to leading researchers, this all comes down to a cellular process called autophagy. Autophagy is what happens in the body when cells clean house and the weak ones die off. This makes room for the regeneration of new, healthier cells and tissues, which affects longevity and helps reverse diseases of all kinds. In other words: Fasting gives your body a break from digesting and allows it to focus on other things. According to Dr. Gundry, this is especially important when it comes to the brain. "The brain needs huge amounts of blood flow. Digestion is incredibly energy-expensive and we divert all of our blood flow to our digestive system" he explained at revitalize 2017.

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What are the different types of fasting?

There are a lot of different types of fasting, so we need to get specific about the terminology we use. So let's break it down:

Intermittent fasting:

Intermittent fasting is a term used to describe a lot of different protocols. One of them is something called time-restricted feeding, which means you restrict the time you spend eating each day to a specific number of hours. This could simply mean maintaining a 12-hour window between dinner and breakfast, which, according to experts, is something we should all be doing. There's also the 16-hour fast, which means you might eat dinner at 8 p.m. and not eat again until noon. A more advanced plan would be to restrict your daily "eating window" even more. For example, Dr. Steven Gundry only eats between 6 and 8 p.m. from January until June. (Keep in mind that this is extreme and shouldn't be done if you're a beginner, and you should always talk to your doctor before making any drastic changes to your diet or lifestyle.)

Also under the umbrella of intermittent fasting is alternate-day fasting and the 5:2 plan. Alternate-day fasting is just how it sounds: You only eat every other day. And the 5:2 plan means you keep your daily calorie intake low (under 600) two days a week.

Prolonged fasting:

Prolonged fasting and fasting mimicking diets are pretty different from intermittent fasting. According to Dr. Valter Longo, "Prolonged fasting and fasting-mimicking diets instead are very different since they last two or more days (usually four or more) and they are not intermittent—meaning that they can be done when needed and not at particular intervals." This includes the ProLon 5-Day Fasting Mimicking Diet, which was developed by Dr. Longo at the USC Longevity Institute. The point of this program is to "allow the body to enter a full ketogenic mode, meaning it will break down and kill damaged cells and cellular components, activate stem cells, and preferentially decrease visceral and abdominal fat." Essentially, their fasts are about longevity and cellular repair.

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I want to start fasting, so where do I begin?

If you want to start fasting but aren't sure where to start, first ask yourself what your goals are. If you're looking to kick sugar cravings and have more energy, you might start with one of the simpler intermittent fasting plans (like a 16-hour fast a few days a week). If you're looking for something a little more extreme and your goal is to promote longevity, then you might sign up for the fasting mimicking diet or talk to your doctor about experimenting with a prolonged fast. Keep in mind that prolonged fasts will require your full attention and are more difficult to incorporate into a normal daily routine, so you'll need to plan ahead. Intermittent fasting is easier to accomplish while sticking to your normal schedule.

Are there any risks associated with fasting?

According to your experts, there are some people who should avoid fasting altogether. First on that list? Pregnant and breastfeeding women. Second is anyone with a history of an eating disorder. The goal of fasting is improved well-being, but it can be triggering for anyone with a history of eating disorders, so it's best to steer clear. According to Vincent Pedre, a functional medicine physician and author of the book Happy Gut, you should also exercise some caution if you have gut issues, food sensitivities, a sleep problem, and anxiety or chronic stress. Going without food can sometimes trigger your fight-or-flight response, and it's important to stay in tune with your body at all times. And as mentioned before, always talk to your doctor about starting a fasting plan, especially if you have any kind of chronic health condition.

How do I take my fast to the next level?

According to our experts, water and black coffee or tea are fine to consume during a fast, and you'll still receive the health benefits. Just don't start throwing back espresso shots to suppress your appetite; this will not do good things for your nervous system. Some experts suggest taking l-glutamine during a fast to stave off sugar cravings and help heal the gut. Another option is to add some MCT oil to your coffee or tea—or sip on some full-blown Bulletproof coffee—during your fast, this will help your body switch more easily into ketosis.

And one last thing: While fasting is great, keep in mind that the way you break your fast is just as important. It's completely counterproductive—and even dangerous for insulin and blood sugar balance—to fast and then immediately binge on unhealthy foods. In other words, don't break your fast by going through the drive-thru or eating a bunch of white bread or sugar. Try a meal with plenty of protein, fiber, vegetables, and healthy fats to break your fast. Your body will thank you!

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