Intermittent Fasting: Does it live up to the hype?

Yes. Intermittent fasting provides many health benefits that can prevent and may reverse several chronic illnesses including type II diabetes, obesity, other inflammation and insulin related diseases, and can help with weight loss. Many of these benefits are completely independent of and in addition to any other health benefits brought on by diet, exercise, and other lifestyle changes.

Beginning intermittent fasting and experiencing the many benefits is easy and can work for just about anyone.

It is always a good idea, particularly if you have any underlying medical conditions to consult your MD before beginning. Some doctors are not up on the current science on fasting (because it is a hot area of research right now and there are currently over 100 clinical trials underway) so, if you need help navigating and initiating this conversation with your doctor, we can help.

It should go without saying, but just to be safe: please know that all information presented in this article is for informational purposes, not for medical diagnosis or treatment.

Would you prefer to watch Intermittent Fasting 101 than read it?

Here are the answers to the 5 most common questions people have when new to Intermittent Fasting:

This is Intermittent Fasting 101, so let’s start with the basics: What is Intermittent Fasting?

Simply put, Intermittent Fasting (often abbreviated IF) is consciously choosing to spend part of your day eating and part of your day resting without food. This is a voluntary cycle that you can follow to lose weight, lower blood pressure, increase mental clarity, and so much more.

There are many different types of fasting schedules, also known as “fasting protocols.” And while theoretically you could intermittent fast for any period of time (even say 1 hour), but typically the most foundational fast is a 12 hour fast.

This means for 12 hours of the day you can consume food and drink as you wish, then for the remaining 12 hours in the day you do not eat anything (drinking water is always allowed). A 12 hour fast is a great fast when you are starting, because it’s shockingly not hard! Most people who are brand new to fasting are pleasantly surprised by how easy it is, give it a try for yourself. I’m quite sure you will be pleased with how much easier it is than you were expecting!

The reason a 12 hour fast is typically easier than most people expect is because you can count your sleeping hours as part of your fast. So, if you sleep for 8 hours a night, you’re really only talking about having to fast for 4 waking hours. Not too bad, huh?

You may wonder, does a 12 hour fast really do anything. The answer is: YES!

Fasting 12 hours has wonderfully positive benefits for your circadian rhythm and gives your digestive system a nice rest. If starting a small, shorter fast is so easy and beneficial, why would you ever fast longer?

The reason is there are many additional benefits that you receive only when you fast for longer periods. These include cellular healing and repairing, stem cell activation, and extending lifespan. Plus, for some (and depending on the quality of your diet) 12 hours is not a long enough fast to begin experiencing weight loss. It may require other protocols to get you the results you are seeking.

 Is Intermittent Fasting a trend that will continue or just a fad (like Beanie Babies)?

Intermittent or otherwise, fasting is definitely not a fad. Humans have evolved to withstand prolonged periods without food. Our prehistoric ancestors did not have drive-thru restaurants or spend hours snacking on chips. Humans have experienced routine periods of famine throughout our 300,000+ year history. While they were unlikely choosing these periods of digestive rest, having the metabolic flexibility to do so was key to survive and sustain themselves on body fat when food was scarce.

Humans throughout history have chosen to fast routinely. Every major world religion (including Buddhism, Christianity, Hinduism, Islam, and Judaism) all have a fasting tradition. The reasons for fasting in each faith varies slightly, but all encourage their followers to fast as part of enhancing their spiritual practice. It is often used as a way to show devotion, achieve religious breakthroughs / spiritual awakenings, and seek redemption.

Suffice it to say, fasting and Intermittent Fasting is not a new trendy diet, but rather an ancient human practice.

In modern days, processed foods – particularly sugar and refined oils – have been linked to the rise of chronic diseases like obesity, type 2 diabetes, and other metabolic diseases. Regular consumption of these foods often eventually lead to both acute and chronic diseases that modern medicine is ill-equipped to reverse. It is no secret that the treatment for chronic illness are failing millions where treatments are focused on symptom mitigation and rarely reverses the underlying root cause.

It is because of this lack of adequate treatment of chronic disease that The Fasting Flamingo exists. Katherine Olaksen, the founder, worked in kidney dialysis and was disturbed by how the leading cause of kidney failure, type 2 diabetes, was reversible through fasting and lifestyle changes. However, since this is not widely understood by medical professionals today and a prevailing belief that patients would be unwilling to make such lifestyle changes, patients are often not educated on this choice. Instead, in many patients type 2 diabetes progresses and the consequences are severe. 20-30% of these patients will develop kidney disease and many will go on to end up in full-blown kidney failure. This leads to a significantly diminished quality of life and on average a significantly shorter lifespan.

But, what if I get Hangry?

Many fasters are surprised to learn that their so-called “hanger” actually stems from habitual behavior, sugar or processed food cravings, emotional triggers and external cues (like seeing their favorite bakery or what their partner is eating) that makes them feel like they must have food, but after they began fasting they started to realize that they were actually rarely “hungry”. Far more often it is craving, addiction, or habit that drives them to the fridge.

You too will likely be stunned when you realize how often you eat not due to actual hormone-driven hunger, but due to one of the many other eating triggers.

If you want to free yourself from this kind of mindless eating. A good place to start is in the moment you feel your “hanger” or a craving coming on, notice what triggered it. And, then ask yourself:

Would I happily eat plain boiled broccoli right now?

If the answer is “no,” but you are still “hungry” for a tastier treat… here’s what is likely going on:

• Emotional hunger:  A desire to change a state through food (ice cream after a break-up anyone?) and is typically caused by stress, boredom, pain, or feeling overwhelmed or overloaded.
• Social: There is subtle pressure, whether you’ve ever noticed it or not, to eat at certain times of the day (breakfast at 9 am, lunch at noon, etc.). We center social engagement around food (how often do your friends or family get together and it doesn’t involve food?) We have certain foods at certain places such as popcorn at the movies, and snacks on the plane. Even as a child, you needed to be part of the “clean plate club” and to have at least a bite of any dish a friend offers (especially if they made it themselves specifically for you).
• Environmental Triggers: Think Cinnabon smell at airports and malls (that’s no accident), restaurant and grocery store layouts are designed to entice you to eat and buy more. Even just a co-worker walking by with a delicious looking plate of food, or a juicy looking advertisement on TV…  can causes your mouth to salivate and your desire for food to increase. Or even coming home at the end of a long day can be the cue to get your stomach gurgling.

Being aware of these common factors and then watching your own behavior over the next 24 hours, will help you to begin to understand the difference between true hunger and all those other times you eat.

We also like to say, “eating begets eating,” and you may start to notice this too. If you aren’t eating you’re not that hungry but after you take that first bite, suddenly your hunger rises to meet the occasion.

This can become an issue if you eat when you aren’t hungry. Overtime, you can slowly start to lose track of whether you are actually hungry or you are just craving a particular feeling. Routinely and consistently confusing these cues can lead to weight gain, insulin resistance, inflammation, and many health issues that thankfully can be reversed through intermittent fasting.

What Are the Different Intermittent Fasting Schedules?

Short duration Intermittent Fasting working up to 12/12:

Fasting allows for a wide range of protocols that can be flexible to your schedule and needs. While the definitions are a little murky, Intermittent Fasting is typically fasting for less than 24 hours (though sometimes you will see it as 48 hours or less). As previously mentioned, 12-hour fasts are for beginners and allow for a lot of flexibility because it depends on your sleep schedule. It is great when you can piggy-back on your sleep and get those free bonus hours!

Starting with your sleep makes it easy to build upon and can allow for great flexibility depending on your habits and routines. For example, if you love to eat breakfast with your morning cup of coffee, begin you fast after dinner from the previous day. Starting your fast that night allows for you to incorporate your typical 8 hours of sleep and complete anywhere from a 9-12 hour fast.

If you are brand new to fasting, we recommend growing your fasting window gradually by 30 minutes at a time over the course of a week or two, until you are able to comfortably do a 12/12 fasting schedule. A 12/12 (also written as 12:12) means you spend twelve hours of a 24-hour period not consuming any food or caloric/sweetened drink and 12 hours during which you have your meals and drinks. For most it will be easier than you think to work yourself up to 12 hours of fasting each day and you will receive considerable benefits for doing so!

16/8 or 16:8 Intermittent Fasting Protocol

Once you have mastered a 12 hour fast and feel ready for more, the next big step is typically a 16 hour fast with an 8-hour eating window (16/8). Once again, this eating window is not a binge free for all, but a time where you allow yourself to have a few normal and well-balanced meals. This fast can be accomplished by building upon the 12 hour fast. Again building on your existing fasting window by adding 30 minutes at a time over the course of a few weeks.

An example of how a 16/8 fasting protocol might work:

You finished dinner at 7 PM last night and had nothing except water before bed. You then fast until 11 AM today and break your fast with a delicious brunch. After brunch you may have another meal or two, completing your eating by 7 PM again tonight. Not to bad, huh?

Repeating this schedule daily, will make it is easier to incorporate than you might think. Your body will get used to the rhythm. And you can feel great knowing that you are just creating a schedule that allows for periods of significant digestive rest.

18/6 or 18:6 Intermittent Fasting Protocol

Similar to a 16/8, an 18/6 fast just extends the fasting window by two hours. Instead of completing dinner by 7 PM, you finish your fast at 5 PM or you have your brunch two hours later. Or some other combination that totals 18 hours in a fasted state and six hours for your eating window.

How a 18/6 intermittent fast could work:

You finished dinner at 6 PM last night,  you then break your fast today at noon (for that delicious brunch) and continue your eating window for 6 hours. By 6 PM, you wrap up eating and begin your next fast. If this is too “early bird special” for your lifestyle, you could have your fast end at 1:30 PM and give yourself until 7:30 PM to eat. That’s the beautiful thing, it is flexible! Though there is some evidence to say that eating earlier in the day is better for our circadian rhythm.

No matter how you choose to approach it, please make sure you build gently and are listening to your body. Aggressively jumping into fasting is similar to over-exerting yourself at the gym and then pulling a muscle. It is definitely better to build slowly and gain fasting confidence.

There are lots of Intermittent Fasting protocols to choose from!

But we’re guessing that you’re getting the pattern. Just to be sure, here are a few other common ones:

• 17/7: You guessed it, 17 hours fasting and 7 hours for an eating window. While less common than both the 16/8 and 18/6, some people love and get great results from this variation.

• 20/4: Same pattern, 20 hours fasting and 4 hours to get your meals in.

• 23/1: Also called OMAD is the one we’ll talk about next. 

One Meal a Day Fasting (OMAD):

OMAD fasting is stricter than the other fasts listed above. The strictest definition is one meal in a one hour eating window each day paired with 23 hours of fasting. But the definition of OMAD can vary depending on who you’re talking to and how long they like to drag out their one meal. Some will say they have one meal a day in a 1-4 hour time-frame and thus it still qualifies as “one meal”.

While the exact definition of OMAD may be disputed, it is definitely a stricter form of fasting than 18/6. And, if the OMAD is more of a four hour eating window it can also be described as a 20/4 fast.  OMAD may be extreme for many because of the stricter eating time. If you are prone to binge eating or anything like that, OMAD may be too strict of a fast for you to use. Make sure listen to your body and that you are ALWAYS fasting in a way that supports a healthy lifestyle.

A similar fast to OMAD, is a 24 hour fast and may be easier to plan, because there is no restricted eating window once you resume eating (you can choose whatever works best for you).

Here’s how a 24 hour fast works:

If you begin your fast after lunch today at 1 pm, you will not eat until 1 pm tomorrow. But once you break your fast at 1 pm, you do not have to adhere to a strict schedule. You can switch between 24 hour fasts and smaller intermittent fasts such as 12 hour, 16/8, and 18/6 if you’d like. Or some people like to start their week off with one 24 hour fast and then eat however they choose for the remainder of the week. And, the nice thing about the 24 hour fast is, it isn’t as hard as it sounds at first, because you do get to eat at least one meal each day if you plan your timing!

Alternate Day Fasting (ADF):

Alternate day fasting builds upon a 24 hour fast and is more of a weekly intermittent fasting schedule rather than a daily one. A typical schedule includes fasting for even days of the week and eating on odd days (or vice versa). With ADF you typically fast for 36-44 hours and then have a 12 to 8 hour eating window during one day.

When beginning ADF and longer fasts, make sure to break your fast gently with a food such as broth, milk (if you’re not sensitive to dairy, this was a very popular way to break a fast around the turn of the century), a handful of nuts, or something similarly gentle on your stomach to gently reawaken your digestive system.

Once you get good at the alternate day fasting, consider yourself an intermediate faster! Maintaining this level of intermittent fasting will begin to steadily show results of mental clarity, reversing insulin resistance, and can be a great way to drop weight. It also gives you the skills you need to explore extended fasting (should you choose to).

Extended Fasting:

Completing an extended day fast (48+ hours of fasting) is not for everyone and you may need additional clarification from your doctor if this fast is right for you and your body. However, there are some good reasons to consider it. Completing an extended fast can have additional benefits beyond those experienced during shorter duration intermittent fasting.

These benefits include increasing the human growth hormone (HGH) to stimulate muscle growth, cell regeneration and reproduction, increased mental clarity, helping reverse insulin resistance, stem cell growth, autophagy, healing of the digestive system, and reduction of asthma symptoms. It has also been shown that many of your organs (except for brain and reproductive organs) shrink during extended fasting, but they return to their original size when you resume eating. While this may sound strange, it appears that this may actually improve their function and be a similar concept to ringing the dirty water out a sponge.

Unless you have an extreme condition that requires immediate intervention and you are being medically supervised, it is best not to jump right into extended fasting, but to work up gradually through completing other shorter duration fasts first. Extended fasts are considered advanced fasts and meant for people with previous fasting experience. Be kind to your body and work your way up to this level gradually!

It is especially important, when completing an advanced fast remember to gently reintroduce food to reduce stomach pains. Breaking a fast with a light broth and waiting 30 minutes to eat heavier food will allow for your body to process food much more efficiently and avoid a rare, but dangerous condition called Refeeding Syndrome.

The Health Benefits of Fasting

Why is fasting so effective in reversing Metabolic Syndrome?

First, what is Metabolic Syndrome?

Metabolic syndrome is a cluster of conditions that increase your risk of heart disease, stroke, and type 2 diabetes. These conditions include increased blood pressure, high blood sugar, excess body fat around the waist, high LDL cholesterol, and abnormal triglyceride levels.

Metabolic Syndrome is not new, and has become increasingly more prevalent. At the time of this writing, 1 in 3 older adults have this condition. However, fasting can play a key role in reversing many of these symptoms. Research consistently demonstrates that intermittent fasting is one of the best methods for reducing excess body fat and many of the conditions that go along with it.

In fact, type 2 diabetes, can be reversed with long term intermittent fasting. Type 2 diabetes in the last 10 years is being re-understood thanks to the work of Dr. Jason Fung and others. It is essentially a disease of chronically high insulin that progresses very gradually, typically for many years patients won’t know that they have high insulin, then the begin to get symptoms of insulin resistance, then prediabetes and eventually (often decades later), full blown type 2 diabetes.

What makes fasting so effective in fighting this progression?

Fasting allows for periods of time where blood sugar can decrease naturally, this allows insulin levels to fall too and over time insulin sensitivity can be restored naturally.

Does intermittent fasting prevent or reverse cancer?

Does intermittent fasting help with inflammation related diseases?

Consistent intermittent fasting reduces inflammation throughout the body and can be used as a remedy for many inflammatory related diseases including asthma, rheumatoid arthritis, chronic pain, Alzheimer’s, Crohn’s disease, and other similar conditions.

While the health benefits of intermittent fasting may seem almost to good to be true – this is evidence-based. Every benefit we cite in this article has strong peer-reviewed scientific evidence supporting these claims. A 2009 New England Journal of Medicine states,

“Many of the health benefits of intermittent fasting are not simply the result of reduced free-radical production and elicits evolutionary conserved adapted cellular responses that are integrated between and within organs.”

In addition to the health benefits mentioned above, intermittent fasting does a few more beneficial things:

• Fat for fuel: Intermittent fasting allows for our bodies to use up a different energy system than just glucose and fat, but ketones. Ketones seem to be a great fuel source for our brains and contribute to the mental clarity and positive effects so many people find fasting has on their brains.
• Extends lifespan: Intermittent fasting in mice and rats has been shown to significantly extend life span and it is likely true for humans too. It’s just it takes a long time to show humans are living materially longer. 🙂
• Healthy Cells: Intermittent fasting increases cell growth and plasticity as functional and structural tissues remodel.
• Makes you smarter: Intermittent fasting increases BDNF = Brain Derived Neurotrophic Factor, a protein that increases neuron growth. Yes, you’re reading this correctly, it helps us to create new brain cells and makes us “smarter.”
• Prevents neuroligical diseases: Intermittent fasting in some of the amazing work by Dr. Mark Mattson at John’s Hopkins University has been shown to increase brain stem cells and to reduce the symptoms of or prevent neurological diseases including Parkinson’s, Huntington’s, and Multiple Sclerosis.

We could go on, but we think you get the idea… Intermittent Fasting is POWERFUL for our bodies and minds.

Intermittent fasting sounds amazing, what’s the catch?

Fasting provides many benefits, but there are a few negative side effects that may come up particularly when you are new to fasting, such as:

• Headaches
• Hunger and cravings
• Lack of social acceptance
• Lethargy or feeling unwell

Headaches

To prevent headaches, make sure to be drinking an adequate amount of water and make sure you are getting plenty of sleep. For most people, having water w/some salt will help reduce the frequency and duration of headaches and the really good news is they do go away the more you fast. Be sure you are not putting yourself through excessive pain or stress. If you need to break a fast early, that’s an option. You can always try again another day! Make sure to listen to your body and do what is best for you.

Hunger/Cravings

Overcoming hunger and cravings can is more of a mental challenge than a physical one. We like to say,

Fasting is 90% mental and 10% JUST DON’T EAT.

If you experience minor hunger and cravings push through them to complete your fast. It will make it easier for the next time. And, will make you proud of your accomplishment.

Set yourself up for success as much as possible by not having tempting foods or snacks near you during a fast. Cleaning up your environment always makes the experience much easier.

Social

Explaining intermittent fasting to family members and friends may be difficult as there is a lot of misinformation about fasting. Often when people are first getting into intermittent fasting, they follow the “First Rule of Fasting” and do not talk about fasting. Only tell those who need to know and who will be supportive about what they are doing.

If you are the only one fasting in your home, it may help to plan your eating window during typical dinner time for your household.

Make sure you take advantage of the flexibility of fasting! Dinner invites may feel awkward if they don’t fall within your eating window, but the really nice thing about this lifestyle is you can move your schedule when you want to work around an engagement – moving your fasting window up or back a few hours as needed to accommodate real life.

Feel unwell or fatigued

If you feel ill or like something is materially wrong in your body. Absolutely listen to that! That’s a great reason to break a fast. It is particularly important to break your fast if you have underlying health conditions that you take medications for. Fasting in many cases will start healing you so quickly that you actually run the risk of over-medicating yourself (which can be quite dangerous) if your MD is not frequently checking your lab values and lowering your doses as you heal naturally through intermittent fasting.

But, if it is not actually a sickness — just a temptation siren calling to you – do your best not to give in. The more you practice this the easier it gets – we promise!

Want to know even more about Intermittent Fasting? Here’s the FAQ:

How does Intermittent Fasting effect blood pressure and blood sugar?

Intermittent Fasting has several effects on your blood including, lowering blood sugar (hyperglycemia), blood pressure, and cholesterol. These are common health problems encountered by over half of adults in the United States and they have all been shown to be improved with consistent intermittent fasting. It’s pretty amazing! Fasting allows your body to essentially reboot itself if not back to original factory settings at least into a healthier state.

How does Intermittent Fasting impact type 2 diabetes?

Type 2 diabetes can be reversed as shown through the work of Dr. Jason Fung and Megan Ramos amongst others. This benefit is just beginning to make it’s way through the medical community and has not even begun to be harnessed to its full potential. A metabolic shift with fasting allows for your body to begin lowering insulin levels naturally allowing you to access fat stores and fuel the body through stored fat. Overtime both insulin and blood sugar naturally decrease and with regular fasting over typically several months insulin sensitivity can be fully restored. Type 2 diabetes is a disease of insulin resistance, so restoring this sensitivity reverses the condition. It is very important though, that during this process you are monitored by a supportive doctor and this is doubly important if you are taking any medications.

Can intermittent fasting really help me to lose weight?

So many people get into intermittent fasting for the weight loss, and it definitely does do that! Just check out Angus Barberri if you need a little proof! But so many of us STAY fasting long after the weight has come off because of all the other amazing benefits.

Weight loss via fasting is very different than traditional Calories In Calories Out (CICO) counting, because of the hormone INSULIN.  Insulin tells our fat and muscle cells to take up the glucose in the blood. Or, when there is not enough glucose present, the absence of insulin signals our fat cells to release fat from the cell to be used for fuel. It is an incredible process that helped our ancestors to survive intense periods of famine. The only problem of course is, that we now have the opposite problem. A tsunami of sugary, processed, calorically dense food.

Traditional CICO diets do not account for the fact that insulin, leptin, and ghrelin (amongst other hormones) regulate our fat storage. While CICO works in lab rats where there food is controlled. We’re at an all-you-can-eat-buffet from an evolutionary point of view and frequently eating a high-sugar or processed food diet exacerbates this hormonal problem.

What is this “a-word” I keep hearing people rave about?

Autophagy is the body cleaning and removing unnecessary micro-cellular components and keeps your body healthy. This “self-eating” process won the Nobel Prize in Medicine in 2016 and is often compared to a housekeeping process we have within each of our cells. When we consume food frequently (particularly protein), we keep a switch in our body set to “growth-mode” and we are unable to access the state of autophagy. However, when we fast or exercise very intensely, we can flip this switch and allow our cells to heal and repair themselves. This is a time when mitochondria (the engines of our cells) can break down and repair, DNA repair can also occur, and there is evidence to suggest that this can help to prevent certain types of cancer from developing.

While this healing process, autopahgy, goes back as far in our evolutionary history as yeast, and was initially discovered in the 1940s we are only beginning to uncover just how powerful it is and how to harness it for optimal health. At the time of this writing, there is no biomarker for autophagy, so you can’t find out how many of your cells (if any) are experiencing this state. Hopefully soon we will know much more about this amazing healing process.

Does Intermittent Fasting interfere with my hormones?

IF triggers and balances many hormones like insulin, as well as some you may not be expecting like Ghrelin, Leptin, and Human Growth Hormone (HGH) and sex hormones.

HGH naturally and significantly increases while fasting. HGH does so many amazing things in your body from increasing muscle mass and bone density to increasing exercise capacity as well as maintains tissues and organs throughout your life.

What else does Intermittent Fasting do?

Fasting can provide benefits for your circadian rhythm, increase mental clarity, improve mental health, and can even spur digestive stem cells regeneration. Fasting allows for your body to gain additional benefits and feel better in your own skin (literally!). After following intermittent fasting, many report feeling less bloated and overall bettered emotions.

Is it safe for women to Intermittent Fast?

Early in the Intermittent Fasting revolution there were a few folks that said concerning statements along the lines of “Women need to be careful when fasting” or “Women shouldn’t intermittent fast.”

There is little scientific evidence supporting these claims. And, in fact for some women’s health issues fasting has proven to be a great treatment.

Over 10% of women suffer from Polycystic Ovarian Syndrome (PCOS) and this can often lead to infertility issues. Women’s hormones can be out of line and fasting can help restore these hormone levels and increase ovarian functions.

“The bottom line, then, is that three defining features of PCOS-hyperandrogenism causing masculine features, polycystic ovaries, and anovulatory cycles – all reflect the same pathophysiology: too much testosterone, ultimately caused by too much insulin. Simply put, too much insulin causes PCOS.”

– The PCOS Plan

Sound familiar? Insulin plays a big role in Obesity and Type II diabetes too. It seems that PCOS is just another symptom of the same root cause that fasting addresses.

Additionally, fasting can reduce menstruation effects of bloating and cramps and over a longer course of time (6 months or more). Intermittent fasting is safe for women on their period. Do not go extended days without eating, and always listen to your body. Short fasts pose no significant health risks for women on their period and are still beneficial and allows for that euphoric feeling that may slightly diminish when menstruating.

Since weight loss is one of the many perks of fasting, fasting for women over 40 can be extremely beneficial. Due to the hormonal changes experienced and during menopause, fasting can be beneficial. Many common issues experienced during this time include weight gain, sleep inconsistencies, and mood changes. If done right, Intermittent Fasting can help reduce these symptoms because fasting can play a role in helping to balance and regulate hormones.

Key Sources:

• The Intermittent Fasting Revolution – Mark Mattson, PhD
• The Obesity Code – Dr. Jason Fung
• The Diabetes Code – Dr. Jason Fung
• The Complete Guide to Fasting – Dr. Jason Fung & Jimmy Moore
• The Fasting Cure – Upton Sinclair
• Eat, Fast, Feast – Dr. Jay Richards
• 2019 New England Journal of Medicine – Intermittent Fasting Article