Intermittent fasting, the new craze: Lose fat by not eating!
“Wait, isn’t that just common sense?”
To an extent, yes. The less we eat, the less fat we store, but intermittent fasting isn’t about reducing how much you eat. It’s about reducing the amount of time spent eating and using a shortened eating window to improve body and health metrics.
When following an intermittent fasting plan, you can still eat as much food as before, but you do so over just a few hours.
“Wait! if I’m eating the same amount of food, then how can I lose fat?”
The answer to this one is a little more complicated and something we will discuss in detail, but before we get there, you should first have a better idea of what intermittent fasting is and the different types of fasting you can engage in.
What is Intermittent Fasting?
The first thing to understand about intermittent fasting is that it is not a diet. You can eat whatever you want while intermittent fasting. Of course, there are going to be foods you shouldn’t eat, and pairing intermittent fasting with a proven diet plan (such as Paleo, Keto, Whole30, etc.) can significantly improve the benefits of intermittent fasting. Still, intermittent fasting itself does not place restrictions on what can or cannot be consumed. Instead, it sets limits on when.
The concept of intermittent fasting is to go prolonged periods, at least 16 hours, without eating food, this is referred to as the fasting window or fasting period. The other 8 hours of the day are referred to as the eating window, or period; any and all food consumption should happen in this 8-hour time frame.
At first, it may seem a little daunting to go 16 hours without food, but unless you’re superman, you probably spend the day sleeping. These sleeping hours can be the start of the fasting window. The typical adult will spend 6-7 hours in bed each night. Using this as an example, if you stop eating two hours before sleep, and then don’t usually eat for the first hour or two after waking up, you’ve already hit a 10-hour fasting window. Extend this out a little on either side, and you’ll be pretty close to the 16-hour mark.
With this type of set up, a 16-hour fasting window can be relatively easy to achieve. If you can stop eating at 7pm each night, that means you can start eating again at 11am the next morning. Through in the hectic work schedule, we all love to brag about, and those few hours you actually spend awake will be sped by.
When first starting out, you will notice regular hunger cues. Still, the body is infamous for its ability to adapt, especially once it knows a circumstance has become it’s new normal. Give yourself an adjustment window of a week, and your body will kick the hunger cues, knowing that food will come at 11am just like the day before.
This is the most basic form of intermittent fasting, so if you feel comfortable with this concept, read on to find out other intermittent fasting strategies.
Fasting Types and Windows
Since this is not a diet, and instead of a strategy for food consumption, it comes in many different shapes and sizes.
The standard concept of intermittent fasting (I.F.), as described above, uses a 16/8 split for fasting/feeding. This is the minimum amount of time that should be spent fasting when using any of the following strategies. The 16/8 split is a great place to start, but as your body adapts to your strategy of choice, try move toward an 18/6 or even a 20/4 split to increase the benefits of intermittent fasting (which we will get into next).
This basic form of intermittent fasting can be used in a few different ways. We shall start with the easiest form of I.F. to get into, and that is the weekly fast1.
Weekly: Performing an intermittent fast once a week is by far the easiest form of fasting to implement when starting out. For this strategy, choose one day each week; let’s take Tuesday, for example, to try out your 16/8 split. On Monday night, consume your last meal before 7pm and don’t eat again until Tuesday at 11 am. From here, anything you plan on eating on Tuesday should be done before 7pm Tuesday night. When you wake up Wednesday morning, you can return to a normal eating pattern.
This is a great way to test the waters, but you must recognize that this will not provide a full representation of what I.F has to offer. We should all be able to agree that following a nutrition plan 1 day out of every 7 won’t produce great results.
Don’t get us wrong; any time you can enter a fasted state, you will reap some of the benefits, but again 1 for 7 doesn’t produce the highest standard of benefits. After trying this for a week or two and gaining the confidence that you won’t starve yourself out of existence, try strategy 2: alternate day intermittent fasting.
Alternate Day: This is just as it sounds, enter a fasting period every other day.
Monday begins by eating as normal but have your last meal before 7pm. Enter your first fasting window by not eating until Tuesday at 11am. Consume all food before Tuesday at 7pm. Wednesday, wake up and eat as normal but have your last meal before 7pm. Enter your second fasting window by not eating until Thursday at 11 AM… Get the idea?
This strategy will significantly increase the benefits you begin to experience from intermittent fasting and is often the bridge between those who are just trying something new and those who are ready to dive headfirst into intermittent daily fasts.
Daily: Daily fasts are the toughest to perform at first. The mental aspect will be significantly challenged as hunger rises, and the body is figuring out how to adapt. These side effects only last a few days, though, and if you can stick it out the first week, you’ll be home free.
Following a daily I.F. schedule is where all the magic starts to happen. All the benefits of this eating strategy are in full swing, and you will see results faster than ever. Adapting to a daily 16/8 split also makes it easier to try an 18/6, 20/4 split, or another form of fasting as we describe next.
Prolonged fasting exposes the idea that more is better. This type of fasting lasts for 24 hours and should only be performed once a quarter (once every 3 months) if performed at all. As we stated before, the longer you are in a fasted stated, the better the benefits become, but fasting doesn’t magically cure the body’s need for food. At some point, you need to eat to continue living; this is why we suggest only performing prolonged fasting once every three months.
Since this fasting strategy is performed so infrequently, most decide to skip it altogether, which is perfectly fine. We list here, so you know the options available to you.
The last form of fasting we will touch on is the liquid fast. Like the prolonged fast, this lasts for 24 hours, but unlike an extended fast, liquids can be consumed during the fasting window. This isn’t a free for all to down your favorite chocolate banana protein smoothie; the liquids consumed during this time are used to help heal the gut and give your digestive tract a break. If performing a liquid fast stick to water, teas (no added sweeteners or creams), broths, or black coffee2
Intermittent fasting can be implemented at any level; the level you choose, though, can significantly affect the level of benefits you experience.
Benefits of Intermittent Fasting
There is a reason why intermittent fasting is a popular eating strategy; in fact, there are many reasons why, which we will discuss next. One more quick side note before we get there though:
16-hours is the minimum amount of time you need to spend in a fasted state to unlock these benefits, and this is exactly how you should be viewing them. The benefits of intermittent fasting are hiding behind closed doors that need to be unlocked by staying in a fasted state. The longer you’re fasting, the more doors you can unlock.
A 16-hour fast will grant you the physical benefits and some of the mental or cellular benefits, while an 18 or 20-hour fast will give you the master key to unlock everything I.F has to offer2.
So without further ado, the physical, mental, and cellular benefits of intermittent fasting:
Aside from being the most noticeable benefits of intermittent fasting, the physical benefits are also the easiest to unlock. Even with the minimal fasting window, you’ll be able to reap these benefits.
Boosts fat loss: Fat loss is at the top of everyone’s list. There’s no denying the desire to shred fat so we can show off the sexy six-pack we’ve been building. Intermittent fasting is one of the best ways to help achieve this goal.
There are a few mechanics that come into play when fasting that will boost fat loss, but we are going to focus on the two most effective pieces. First is that the shortened feeding window will naturally lead to a decrease in calorie consumption. It’s hard to keep eating when your last meal was only an hour ago, but you know the eating window ends in thirty minutes. Since you don’t feel as hungry during the feeding window (once your body has had time to adjust that is), you will subconsciously eat less during the day.
In most cases, this is of no concern. The general population tends to over-consume calories (this is part of the reason why there’s excess body fat, to begin with), and we see that those on an intermittent fasting program eat closer to their actual caloric needs. When you stop overeating, it becomes relatively easy to drop a few extra pounds.
The second mechanism is the body’s ability to control or regain control of insulin production. Insulin is a hormone that helps the body regulate blood sugar. When we consume foods, insulin is released to transport sugars through the blood and to the cells for usage or storage. Even if you aren’t eating sugar-laden foods, any form of carbohydrate that is eaten will be broken down into sugar for easy transport within the body.
When we are continually consuming foods, and consistently producing insulin, the body can learn to ignore insulin signals. This leads to abnormal blood sugar levels, an inability to regulate sugar usage, and an increase in food storage, leading to increased body fat levels.
When we stop eating for periods, the body stops producing insulin. This is excellent news! Intermittent fasting requires long periods without eating, which means long periods without producing or releasing insulin. Subsequently, when insulin does become present, our body is more susceptible to its signals and is better able to regulate blood sugar transport and usage. In addition to this, when insulin is not present but the body is still in need of energy, it knows that extra energy has been stored in the fat cells, so it will start burning away these stubborn areas.
Muscle gain: Contrary to popular belief, I.F. can be an excellent way to improve your strength and muscle mass. When appropriately done, YOU CAN BUILD MUSCLE while fasting.
When you are in a fasted state, you are putting stress on the body, this is a good form of stress though that forces your body to adapt. Part of this adaptation is the body releasing hormones that we shall call catecholamines- for those super nerds out there, these are adrenaline, epinephrine, and norepinephrine. These hormones are released in the response of the body’s need for fuel, but they tell the body to release fat and preserve hormone for its energy needs3
But wait, there’s more…
The release of these catecholamines also triggers the body to constrict blood vessels and limit the areas of blood flow. This process reduces blood flow to smaller muscles and pushes blood flow to the large muscle groups, such as your quads, glutes, or lats. The blood carries glucose and oxygen, the two main components of energy production, to wherever it is needed throughout the body. By constricting blood flow to the smaller muscle and focusing circulation to the larger muscle groups, the body can preserve what energy is available and feed just these larger muscles. In return, these muscles gain all the benefits of energy production and blood flow, allowing them to grow in response to an exercise stimulus during a fasted state.
This second benefit only comes into play if you are working out during your fasted window, though; later in this article, we will further discuss the benefits of exercising while fasted and when is the best time to exercise if you are following an intermittent fasting program.
Improve standard health metrics: Aside from being an amazing fat loss program and strategy to build or maintain a toned physique, intermittent fasting can increase various health metrics that are currently plaguing the adult population.
We have all been warned about the dangers of cholesterol and high blood pressure, are aware of insulin resistance and its role in chronic disease, and the importance sleep plays in boosting the immune system; well, intermittent fasting allows your body to take care of all of these things. Consuming your daily calories within a compressed time frame dramatically reduces the production of insulin and helps regulate cholesterol4. Keeping both of these in check will also lower blood pressure.
Along with this, your body will get into a routine of when it is or isn’t eating. This routine strengthens your personal clock, referred to as your circadian rhythm, and makes it easier for the body to predict when things are supposed to occur, such as sleep. If you keep the same schedule day in and day out, your body will subconsciously begin to produce the “sleepy time” hormones as bedtime approaches. This leads to longer bouts of sleep and higher quality sleep, which boosts immune activity and recovery from workouts. Don’t you wish every diet plan could improve your sleep quality? A great night’s sleep is just one-way I.F. boosts mental capacities too.
Now its time for the mental health benefits of I.F.
To start us off is the benefit of increased focus. Those who have tried any form of fasting can attest to the hypervigilance it can produce. As the fasting window grows more extended, our brains become more focused and excited by tasks that are immediately in front of us. Why is this?
Well, fasting for any significant period (12+ hours) causes the body to enter into a “starvation mode.” This is a preservation mechanism from the caveman days that has stuck around to the modern period. Back then, it was common for humans to go significant periods without adequate food- you didn’t always finish a hunt with a meal in hand. Because of this, the human body became very efficient at preserving energy in times of little to no food consumption.
Part of this energy consumption is our body’s ability to cut attention away from unnecessary items or tasks. The brain is a high energy-consuming organ, it should be because it is in charge of organizing and responding to literally everything that goes on around us. On a typical day, the brain can account for 20% of our body’s energy needs5. Our brains consume a HUGE portion of the energy we can produce. By cutting attention to unnecessary items and tasks, we preserve a significant part of the energy needed by this all-powerful organ.
This consumption of energy results in a laser-like focus as the brain turns all its attention, power, and energy to the task at hand, writing off everything else in an attempt to keep energy needs low.
Moving beyond your newfound hyper-focus, studies have also shown that intermittent fasting6
- leads to the growth of new nerve cells in the brain, to increase the brains efficiency and further preserve energy
- increases a hormone called brain-derived neurotrophic factor (BDNF), which combats depression and mental illness
- protects against brain damage, and in particular, reduces the risk of strokes
Intermittent fasting has profound benefits on health and longevity, and we have just scratched the surface on the longevity part.
One of the benefits you will see listen in any article on intermittent fasting is that of autophagy, but what does this word even mean?
Autophagy is the scientific term for cell recycling; it is the idea that new, young, healthy, vibrant cells breakdown and consume old cells. This is a natural process that happens to millions of cells within your body every day. This explanation might lead you to wonder, ‘if this is a natural process, then why is it always listed as a benefit of intermittent fasting?’
Again, we go back to the idea of preserving the body. Preserving energy, maintaining function, and, most importantly, preserving healthy cells. For the body to run optimally when under the “stress” of fasting, it needs to have the healthiest strongest cells. The body is very adept at recognizing these cells too.
As we enter a fast, the process of autophagy increases, the healthy cells start consuming the old cells at a higher rate to ensure the strongest cells possible are available to handle regular bodily functions. The longer we remain in a fasted state, the more this process increases2. Intermittent fasting helps enhance our body’s process of cell recycling and repair, keeping the strongest most efficient cells alive to maximize your daily functions.
Now that we have exhausted the benefits of this eating plan let’s take a look at some of the risks associated with intermittent fasting. Yes, this is a lot this paradigm has to offer, but there are still some things to consider before jumping into a fasted state of being.
Risks of Intermittent Fasting
Intermittent fasting will not be the same for everyone. We’ve already unveiled different fasting strategies, so next, we will discuss how your fasting window can, and in some cases, should be altered.
If you have any preexisting long term health condition- such as diabetes, an autoimmune disorder, IBS, or any other disease that requires frequent checkups and/medications, consult your doctor BEFORE trying intermittent fasting.
The hormonal changes we touched on in the benefits above are just the tip of the iceberg when it comes to biochemical changes your body will experience when in a fasted stated. For this reason, you should always speak with a registered dietician or your standard care doctor before making drastic changes to your eating strategy or diet.
Men vs. Women
Ladies, we need to backtrack for just a moment- if you’re a dude reading this, you can skip ahead to the next risk factor because this one just pertains to the females.
A woman’s body naturally has higher amounts of fat on it, and this is a good thing! Women need to have fat on the body to support reproductive function. If you are pregnant or trying to get pregnant, consult a physician before starting your first fasting window. It is still possible to use intermittent fasting as an eating strategy during this period, but be upfront with your physician to ensure you are maintaining healthy fat levels to support your baby.
If you are not in this stage of life, you still need to be mindful of this critical biological difference between a man and a woman’s body. Having, and needing, higher amounts of body fat reduces the amount of time required to be spent in a fasting window. I know, I know we’ve been stressing the 16-hour minimum, but the truth is women can start to see benefits at the 12 or 14-hour mark, and this can be a mental relief to you as well.
Since women need to maintain a higher body fat percentage, to protect their reproductive processes, it can be harder to follow a standard intermittent fasting split. Your bodies will put up more of a fight and take longer to adapt, which may lead to increased hunger, mood swings, and irritability. It’s ok if you need to step it down to a 14/10 or 12/12 split. You will still reap the physical and some of the mental and cellular benefits of I.F2.
Sorry guys, your minimum is still 16-hours.
One concern everyone should be wary of is hydration levels. It is easy for water consumption to fall below normal when following an intermittent fasting schedule. We often tie water consumption to food intake, so shortening this eating window often decreases how much we drink7. Be mindful of how much water you are drinking at ALL times of day, set a reminder periodically if you need to to avoid dehydration.
It is ok to drink water during the fasting period. In fact, it is ok to drink a few things during the fasting period, and these fluids are the next topic of interest we will be discussing.
What you can consume during a fast
A popular debate amongst nutrition gurus is what can or can’t be consumed during the fasting window.
“Hold up, I thought during the fasting window you weren’t supposed to ingest anything? Now you’re telling me this is debatable?”
To an extent, yes. During your fasting window, you should not be consuming anything that has a caloric value.
“Isn’t that everything I put in my mouth?”
Not quite. Some fluids do not contain any calories, such as 0 calorie diet sodas, but we definitely don’t recommend consuming them during the fasting period. Liquids that can be consumed during a fasting window that have 0 calories though are2
Water- this will be the go-to liquid, drink as much as you want
Coffee- consume it black, adding sweeteners, creamers or fats (such as MCT oil or butter) will break the fast
Tea- black or green as long as it is unsweetened and creamer free
Naturally sweetened sodas- ONLY if they are sweetened with stevia and ONLY if they have 0 calories
“Why are these ok and not other drinks?”
These 4 choices all share one thing in common, they are calorie-free! This is very important because a fast can be defined as a lack of calorie consumption. Think back to the fat loss benefit; as soon as you consume calories, insulin will be released, and the body enters the metabolic process of handling sugars; this breaks the fast!! Stay away from any fluids that have calories such as juices, broths, MCT, or fish oil. All this should be saved for the eating window.
“What about diet sodas, they’re 0 calories?”
Yes, but diet sodas use artificial sweeteners that can still trigger insulin production. This is why we suggest naturally sweetened sodas in times of need.
We want to go back to the list of fluids you can drink during a fast really quick before moving on. In particular, we want to point out some of the benefits coffee can offer to a fasting period.
Most adults can already attest to the power of caffeine on focus, so we will skip over how coffee can boost your mental clarity during a fast and skip to the autophagy. Remember that small process of cell recycling? Well, caffeine is a natural enhancer of that process, and on top of this, caffeine stimulates fat burning2. So, keep your morning cup of joe to enhance everything we’ve talked about, just remove the additives…
Instead, try adding in some supplements. If you are one a day vitamin taker, it is ok to take any water-soluble vitamins during your fasting window. The water-soluble vitamins are B and C if your multivitamin contains ANY OTHER vitamins or minerals save it for the eating period. Any other supplements you take- protein powders, MCT/fish oils, BCAAs, etc.- should be saved for the eating period as well.
Consuming supplements with any caloric value will spike insulin, start your metabolism, and break the fast. Even multivitamins wrapped in a soft gel tablet can start this process because the body needs to digest the gel wrapper to get to the vitamin. So if it’s not vitamin B or C, save it for the next topic.
What you should consume during the eating window
Here comes a fun topic, what should you consume during the eating window?
For starters, all the supplements we just ruled out from the fasting window! Here is the time to take the rest of your vitamins, minerals, whey proteins, pre-workouts, or whatever else you need to get you through the day. This is also the appropriate time for consuming broth (which if you haven’t added this to your diet, you’re really missing out on the gut-healing benefits of this fluid), bulletproof coffee or coffee with your creamer of choice, sweetened teas, juices, or whatever fluids you deem necessary.
Beyond this though, the choice is yours. We mentioned it in the beginning, and we will stress it again now: intermittent fasting is not a diet regimen, it is an eating strategy.
Of course, you can enhance the benefits of intermittent fasting with a proven diet plan, so we’ll go ahead and mention some of the popular diets to pair this with.
Keto: Starting with the most controversial diet plan out there right now, the ketogenic diet (keto for short) is all about high fat, low carb consumption. The basic idea behind this diet plan is to switch the body over to using fat for fuel, as opposed to carbohydrates, which can send the fat loss into overdrive. The mechanics behind this diet plan can be just as complicated as intermittent fasting. The hormonal changes produced when your body decides to abandon carbohydrates are just as drastic as introducing a 16-hour fasting window.
If you wish to use this diet plan to further the fat loss benefits, make sure you read up on how to do keto properly. There is definitely a right way and a wrong way to push your body into ketosis, and the wrong way can be pretty frustrating to deal with. So poke around, and get a handle on I.F, before pairing this one up with your eating window.
Paleo: Ah, the Caveman Diet. Justly named for this diet focuses on eating foods that our ancestors developed from. The idea behind the Paleo diet is to reduce inflammation and the risk of disease by eliminating grains, dairy, legumes, and any processed foods. The science backing this food plan is getting stronger every day and is a reasonable consideration for pairing with I.F.
Whole30: Though this is the simplest of the 3 listed here, it does not indicate any decrease in benefit one can gain from following this diet plan. The Whole30 starts as a 30-day challenge to only eat whole foods. Nothing from a box, a can or a bottle. You have to buy all the ingredients, take them home, and make your own foods. This is definitely a challenge but a great way to begin to see the power of eliminating processed foods. The Whole30 can bridge the gap from where you are now to the other two diet plans. This one is more beginner-friendly and still provides plenty of benefits when used under intermittent fasting guidelines.
How to start a fast
“This one seems too easy, why is it listed in this guide?”
Starting a fast can be as simple as stop eating, but trying to start out this way can leave you very hungry craving all kinds of foods you didn’t even know you liked. So, we are here to help you optimally start your fasting period.
The best way to end your eating window, and start the fasting window, is to have a meal heavy in fiber that also contains moderate fats and adequate protein. Fiber will be the most critical part of this meal because fiber slows down digestion. This may seem contrary to what we want since the main idea behind fasting is to avoid digestion and, therefore, insulin production, so lets back up a step.
Food takes hours to digest, and we mean hours. The gut can only process so much at one time, so that last meal you ate is probably still sitting down in there, getting broken up into its nutritional components. The typical meal can take 6-8 hours to pass through the stomach and small intensity.
“If it takes so long for food to break down, then what’s the point of a fasting window anyway?”
When food passes from the stomach and into the small intestines, carbohydrates are typically the first nutrient to be broken down, followed by proteins and then fats8. This is key because carbohydrates are what trigger the insulin response we are trying to avoid in the fasting window. So eating a meal just before the end of the eating window only produces an insulin response until carbohydrates are fully broken down, which can happen within the first 1 or 2.
The rest of the time, we can consider the body to be in a fasted state. The fiber comes into play at this point. As we stated, fiber slows down digestion rates, and since it is left with the proteins and fats, which are slower to digest than carbohydrates, the digestion rates start to compound on each other. Get what’s happening here?
By eating a meal high in fiber with moderate fats and proteins, you are keeping the full gut longer without producing an insulin response (at least not to the level of breaking your fast). You are eating foods that will keep you full longer, reducing the hunger symptom come hours 14, 15, or 16. For those just starting out on your intermittent fasting journey, this will significantly improve your desire to stick with this eating strategy.
Now, unless you are using a straight fiber supplement, you may not know what foods to include to increase fiber consumption at the end of the eating window. That’s what here for, to list some easy to get, healthy foods that are high in fiber:
Pears Brussel Sprouts
Beets Dark Chocolate
There are many delicious foods you can choose from, so there’s no excuse to skimp on the fiber tonight at dinner. Start the fast off right, you’ll thank us tomorrow around 9 AM.
How to break a fast
Breaking a fast properly is just as important as starting the fast. Your body has not ingested any substantial amount of calories for at least 16 hours, now is not the time to dump some nachos down the pipeline…
The best way to break a fast is with broth. We’ve mentioned drinking broth before, and now we are here to discuss how this wonderful fluid can be used to break your fast. Homecooked, or rightfully sourced, natural bone broth is a nutritional goldmine, containing collagen, that is easily digestible.
Your gut has been resting for an extended period at this point. Give it something easy to digest that will also provide your body with a ton of nutrients. Bone broth is low calorie and already in liquid form, so there’s not much work for the gut to do; all that needs to happen is the absorption of nutrients, which there is a lot of.
For starters, bone broth is high in protein, which, if you workout during the fasting window, will be great for muscle recovery and repair. Beyond that broth is also a great source of calcium, phosphorus, potassium, and magnesium9. Which all help regulate hydration levels, bone, and muscle health, as well as support natural cell processes.
The collagen present is also great for hair, skin, and nail growth. This magical liquid provides benefits for every part of your body, and the benefits get layered on top of what was happening during the fast!
Shortly after consuming 4-6 oz of warm bone broth (roughly 30 minutes after), your gut will be awake enough to handle other foods. Now’s the time to satisfy the hunger…
Exercise and Intermittent Fast
If you are on the journey to optimize health by trying something as far fetched as not eating for extended periods, then you are probably well aware of the benefits of regular exercise; so, we won’t go into that here. Instead, we will address the commonly asked questions of
When should I exercise? Is it better to exercise during the fasting window? Or the exercise window? Should I avoid weightlifting? What type of training is best?
When to exercise?
Yet another heated debate among fitness and nutrition gurus worldwide. We’re here to let you know a little secret though: it’s ok to exercise at any time during the fasting OR eating window!
The benefits will vary with the timing of exercise, just like they will with type, duration, and intensity of exercise. When it comes down to it, pick a time that is best for you. That may be what’s best for your schedule (maybe you only have time during your “lunch” break), or when you feel best (after you last meal?), or whenever is right for you.
If you do have the freedom of working out whenever you would like because maybe you are a personal trainer or have a home gym or just a really open schedule, then here are the different times to consider, along with their benefits:
Start of Fast: This is arguably the easiest time to work out because your body has just
come off a fueling period and will be topped off with energy needs. The intensity of workouts can be pushed to a max and sustained because there is plenty of fuel in the tank. If you are going to work out at the start of a fast, make sure you allow for adequate digestion of the last meal. Waiting at least 60 minutes is advised for a few reasons.
If you’ve never worked on a full stomach, you may find it challenging to do so. A full stomach can cause nausea or stomach aches. This is not true for everybody since all our bodies act differently, but if this is your first time trying a workout after eating, don’t go pedal to the metal. Explore how your body reacts to a full stomach first.
The second reason to give yourself some time to digest goes back to carbohydrates. They are digested first and can be a useful source of energy for your muscles, allowing you to turn the intensity to 10.
Lastly, digestion requires energy. Energy that is produced via oxygen delivered by the cardiovascular system. During this time, blood flow dramatically increases to the stomach and gut, so energy production in these areas can remain high. If you begin a workout at this time, the muscles being utilized will have to fight with the digestive system for blood flow and energy components.
Mid Fast: Mid fast exercisers are typically the morning exercisers. These are the highly
motivated individuals that are up at 5 AM just to make sure they get their workout in. We see you, and we commend your dedication.
Your dedication is going to have to get a little deeper, though. Workout mid fast is the toughest time for the body to produce energy. You’re 8 hours away from your last meal, and 8 hours away from the next. The last drops of carbohydrates were digested hours ago, and now your primary fuel source is your stored body fat.
This can be a blessing and a curse. Of course, working out at this time will burn fat at the highest rate, but getting the body to use fat as fuel during a workout is a slow-going process. The body has to recognize the increased need for energy from muscles that are working at a higher rate (meaning your workout has already started). Then it needs to release fat from storage sites; convert it to glucose because the muscles are picky, and this is their fuel of choice; then transport it where it needs to go.
As you can see, these workouts are slow going, and you will have a harder time reaching high-intensity levels. But you’re fat burning processes are in top gear!
End of Fast: You may think this would be the lowest intensity exercise time because you are a full 16 hours away from your last meal, and yes, this is partly true, but the psychological factor plays significantly into these workouts.
Part of intermittent fasting is keeping very structured eating and fasting schedule.
So, the body has an internal clock referred to as its circadian rhythm. Your circadian rhythm helps with daily processes such as falling asleep, waking up, going to the bathroom, and even prepping the body for eating. This is an important one.
When your body adapts to intermittent fasting and recognizes its new eating schedule, it becomes imprinted to your circadian rhythm. This clock will begin to understand when the fasting window is coming to a close, and the eating window is approaching.
“Yeah, yeah, I get it, but what does this have to do with working out?”
If you workout at the end of your fasting window, your circadian rhythm also recognizes this time as the beginning of the eating window and will start to prepare the body for the onslaught of food and digestion. Part of this preparation is the release of insulin to handle the carbohydrate as they come through your system.
If you remember way, way back to our brief discussion on insulin, you may remember us saying that it is responsible for transporting, delivering, AND storing sugar in the body. Well turns out when your circadian rhythm triggers the production of insulin because the feeding window is ending, the insulin makes it easier to transport and deliver the sugars it stored away during the last eating window.
This anticipation by your internal clock helps provide fuel to your muscles for your workout session.
Boom! Internal clock for the win, you get to work out at a higher intensity than mid fast trainers.
The other added benefit to end of the fast training is that you can take your whey protein, your BCAAs, and whatever other recovery supplements you need post-workout because you’re not entering the eating window.
Don’t forget the high protein bone brother for muscle recovery!
During Eating Window: Working out during the eating window is a great way to build muscle mass. This time frame allows you to prime the body with proper eating habits AND jump-starts the recovery process by eating post-workout again.
You’ll be reaping the benefits of fat loss during your fasting period, so don’t be shy about eating what you need to fuel these workouts. Push the intensity, the duration, the weights, or whatever you do because this is the window for maximum gainz.
Now you see why workout timing is a personal preference. If you have a rock hard mentality, try mid fast workouts; if instead, you have a rock hard gut go for the start of the fast period. Try out a few different time frames and pick what suits your needs, your goals, and your schedule.
What exercise program works best?
When it comes to the type of exercise program, there is a little more differentiation. Choosing the right kind of workout will depend on your goals and when you can train.
Cardio: Cardiovascular training is already touted as the training for fat loss (though this is now being challenged by HIIT, we’ll get to that in a minute). Mixing this with intermittent fasting will definitely boost your fat-burning abilities. But this isn’t the only benefit cardio can provide when mixed with intermittent fasting.
If you recall the benefits listed for I.F., you’ll remember there is a huge mental boost when fasting, this boost increases with the fasting period as well as with cardio training. Dr. Domonic D’Agostino, Ph.D. speaks about the benefits of cardio exercise with intermittent fasting and emphasizes the focus and clarity that one can experience from utilizing both mechanisms.
Unless you are engaging in a race, cardiovascular training is typically performed at a moderate intensity. This lower intensity level (compare to weightlifting efforts or HIIT workouts) means you can safely engage in this type of exercise during any training window. A word of caution, though: the longer your cardio session lasts, the more energy you will need if at any point you feel dizzy or light-headed, stop exercising to let your body catch up with energy production.
Weight Training: Weight training while following an intermittent fasting strategy has been a heated topic as of late, the one type of exercise more debated than weightlifting is HIIT, but we’ll save that for last. The concerns raised during debates on weightlifting are that of muscular strength and retention.
Some argue that maintaining or even building muscle while intermittent fasting is not possible, but if you’ve been following along, we debunked that pages ago. It is possible to maintain muscle mass and even increase strength and muscle size if you are going about it in the right way.
For those of you who like to train at the start of the fast and mid fast, it is going to be difficult to increase strength or size; these are seen more like the maintenance training times. The start of the fast period does provide adequate energy to maintain high levels of intensity. Still, a lack of food post-workout can delay the recovery process making it difficult to repair and build muscle. Mid fast lacks food altogether.
For these reasons, if your goal is to increase strength and size, it may be more beneficial to lift during or just preceding the eating window. This will maximize muscle recovery and growth. If you are ok with maintenance for now, then choose whichever window is most convenient.
HIIT: High-intensity interval training… the exercise program that challenges cardio’s title
for fat loss champion while pushing weightlifting off the platform as the ideal strength-building regime.
If you are not familiar with this exercise program, take a moment to reread what HIIT stands for. Gone on, we’ll wait.
That is what this program is all about, and the name should tell you which exercise windows this best fits into.
When engaging in HIIT training session, you are pushing the boundaries of your limits. It is all out, 110%. You need to have fuel in the tank to do this! This type of training, if you want to do it the right way, should be used during or just following the eating period. Word of caution: see how your body reacts to exercise on a full stomach before adding HIIT training to the start of the fasting window.
If added at the correct time, with the proper intensity, HIIT training sessions will amplify fat loss, muscle retention, and all the other benefits of regular exercise.
If you engage in regular bouts of exercise, which you should, the type of activity will have a significant impact on when you will want to train. For any of these training paradigms, though, be aware of how diet choice can play into intensity efforts.
Anyone who does not follow a ketogenic diet will rely on carbohydrates as their primary fuel source. This will not have an effect on energy levels when working out during, or just following, the eating window but can have significant effects if trying to workout mid or end of fast. Your body will not be adapted to using fat as a fuel source, which can delay the process of mobilizing fat for fuel, can temporarily decrease power outputs (strength) or endurance, and may cause dizziness, nausea or fatigue during training.
When first starting out, keep the intensity low and give the body plenty of time to adjust. Over the coming weeks, your body will become more efficient at using fat for fuel, and the numbers will start to come back up in the workout sessions.
This has been an extensive look at intermittent fasting, when and what to eat, as well as when and how to exercise, but the fun isn’t over yet. For the last part of our journey, we are going to look at a few common myths that are often tied to intermittent fasting.
Common Myths and Concerns
Look, there’s a good side and a bad side to everything; there’s no escaping that. But there are just some things out there tied to intermittent fasting that are plain wrong.
People try to put down this eating strategy without fully understand what is happening in the body during a fasting period. We get it, this is a complicated thing to understand. Just look at all the information we’ve provided you already, and this is just the beginning. It’s easy to get lost or try to make stuff up to sound smart, but intermittent fasting shouldn’t receive a bad rap. There are too many benefits it can provide.
So before we close out, we are going to look at 3 myths commonly tied to intermittent fasting and provide a quick explanation of how these thoughts can be dispelled:
Myth #1: Intermittent Fasting Leads to Muscle Loss
Ok, if you still think this is possible, you need to start over, from the beginning, the very beginning…
Muscle and fat loss happen when the body expends more energy than it eats. When following an intermittent fasting regime, you are not required to constrict calorie consumption. The process of shortening the eating window can lead to a natural decrease in calorie consumption, but this is often from the point of overconsumption to a more appropriate level of caloric needs.
If the body does drop into a caloric deficit, the benefits of the fasting period will help preserve muscle mass and target fat loss. In response to the stress of fasting, the body releases catecholamines with act to preserve muscle tissue. These hormones signal to the body that energy is needed AND that it should be taken from the fat stores found in various places. The muscle is left alone.
Outside of this, it is still safe and very reasonable to engage in regular weightlifting or HIIT training sessions, both of which help maintain or even build muscle mass.
Myth #1, dispelled.
Myth #2: Intermittent Fasting Leads to a Drop-in Metabolism
Intermittent fasting leads to a shorter time frame of metabolic activity, not to an overall drop in metabolism.
Metabolism is the process of converting what you eat and drink into energy. It shouldn’t be a surprise that when you stop eating for long periods, say 16-hours or more, your metabolic rate slows down. So this semi supports myth #2; however, when most people spout this myth, they are referring to overall metabolic rates and the concern that over time your body will become less efficient at converting food to energy.
This myth tries to say that the longer you engage in intermittent fasting, the less efficient your body is at making energy, and the slower your metabolism works, even in the presence of food. This is not true.
Your metabolism will slow down during the fasting window, but research clearly shows once the eating window begins, and food is consumed, your metabolism comes right back up to normal levels2.
Myth #2, dispelled.
Myth #3: Alcohol Consumption Negates the Fat Loss Benefit of Intermittent Fasting
Ok, ok, so we can’t reasonably say this one is a myth because there is some validity. Let’s call it more of a concern.
How is the fat loss process affected when alcohol is consumed on an intermittent fasting plan?
First off, under no circumstances should alcohol be consumed during the fasting window. By now, you should know that consuming any calories during the fasting window will break the fast, spike insulin production, start the metabolic processes, and so on and so forth. Alcohol is not different.
Next, if you are going to consume alcohol, do so wisely. And we don’t just mean watching how much you drink. You should be aware of when you drink. Like everything else we’ve discussed, timing is everything.
When alcohol is consumed, it is put first in the line of things to digest, it even gets placed in front of carbohydrates2. Having other foods in the stomach or gut when alcohol is present, though will reduce the rate at which alcohol can be absorbed and subsequently metabolized. This is very important when discussing fat loss rates.
After the alcohol has been absorbed into the body, it is metabolized primarily by the liver (this is why prolonged, elevated levels of alcohol consumption can lead to liver failure). The liver is also responsible for processing and metabolizing fat in the body as it is released from storage. Since alcohol has the priority, the liver will temporarily turn its attention from processing the fat to metabolism the alcohol.
If absorption rates are slowed down by the presence of other foods in the stomach, the liver is better able to handle metabolism the alcohol in conjunction with processing stored fat2. Therefore, if alcohol must remain in the diet, make sure it is consumed with food to minimize the effects it will have on fat loss.
Myth #3, proven concern and detailed way of handling it.
At first glance, intermittent fasting can seem like an easy concept, after reading through this article the complexity of this eating strategy can be overwhelming. Still, the biggest take-home key is that intermittent fasting should be simple.
Simply don’t consume calories for an extended period.
When you do eat, eat simple whole foods high in nutrition and adequate in calories.
If you choose to exercise, engage in simple tasks that require a level of energy equal to what your body has to offer.
That’s it. It’s that simple. But for all your other questions and concerns, scroll up because we’ve covered it all.
Congratulations, you have made it through the Complete Guide to Intermittent Fasting and didn’t just jump to the Summary section at the end of this article.
Intermittent fasting is not a diet plan but an eating strategy. It is a concept that outlines when you should or shouldn’t be eating. The benefits of intermittent fasting all center around the fasting period, which should last a minimum of 16-hours. The remaining 8-hours of the day are referred to as the eating window and is the time for any and all calorie consumption. Calorie consumption includes foods, fluids, and supplements.
Outside of the eating window, individuals should sustain from any calorie consumption for doing so will break the fast and negates its benefits. During the fasting period, it is ok to consume 0 calorie fluids such as water, black coffee, unsweetened tea, and naturally sweetened 0 calorie soda if needed.
Extending the fasting period, and subsequently shortening the eating window, to an 18/6 or 20/4 split will increase the mental and cellular benefits have to offer. A fasting window of 16 hours is sufficient to reap the physical benefits, which include fat loss and muscle retention, as well as the mental and cellular benefits at a minimal level. Psychological benefits include increased focus, nerve cell growth, and decrease of brain damage. Intermittent fasting also boosts cellular repair by increasing the rate of autophagy (cell recycling).
All these benefits can be gained by engaging in intermittent fasting daily, every other day, weekly, or any time you can enter a fasted state (at least 16-hours of no-calorie consumption). The easiest way to incorporate intermittent fasting is by choosing one day a week to adhere to the fasting/eating windows. After successfully doing this for 2 weeks, boost the benefits by engaging in intermittent fasting on alternate days during the week. To maximize the benefits, and to quickly adapt to a longer fasting window, intermittent fasting should be used daily.
Once every three months, you can also be engaged in 24-hour fasts referred to as prolonged fasts or liquids fasts. In prolonged fasts, you abstain from all consumption, while liquids fast allow for the consumption of 0 calorie fluids (as mentioned before). These fasts can be beneficial to allow the gut time to heal or for added boosts to the benefits of intermittent fasting but are not necessary to experience fat loss, mental clarity, or cellular regeneration.
Intermittent fasting benefits can also be increased by incorporating regular exercise. The type and timing of exercise are critical to consider though. If working out during the fasted window intensity will be lower due to a lack of fuel readily present in the body. During these times, the body will pull energy from fat stores, which will increase the rate of fat loss, but this is a lengthy process leading to a decrease in exercise intensity and/or duration.
If the overall goal of the exercise is to build muscle weightlifting or HIIT training session can be effectively utilized during the eating window. Since calorie consumption is not restricted during intermittent fasting (only time frame of eating is restricted), you can consume enough calories around the workout to support muscle growth.
Since calorie consumption is not restricted during intermittent fasting, the metabolism and metabolic rates will not decrease over long periods. Metabolism slows during the fasting window but will return to regular rates once the body enters the eating window and consumes food.
This also makes intermittent fasting an ideal eating strategy to pair with any diet plan of choice. Popular diets commonly paired with intermittent fasting include the ketogenic (keto) diet, the Paleo diet, and Whole30. The keto diet focuses on using fat as fuel and can significantly increase the rate of fat loss.
The Paleo diet and Whole30 both focus on cutting out processed foods, which can also aid in fat loss but have a higher carbohydrate consumption that the keto diet. This level of carb consumption can make it challenging to work out during the fasting period since the body’s preferred energy source will still be carbohydrates, but adjusting intensity levels will help shore up this side effect.
When implementing an intermittent fasting regimen, pay close attention to how much water is consumed. It is easy to restrict water as the eating window becomes constricted, which can lead to dehydration. Set reminders throughout the day to help with this side effect.
If you have any pre-existing health conditions that require frequent visits to the doctor and/or medications, see your physician before embarking on an intermittent fasting plan. In addition to this, women must understand the reproductive need for body fat. Women typically have higher body fat levels to support a healthy reproductive system. This can make fasting harder on the body; women can still achieve the base level of benefits of intermittent fasting by keeping a 14/10 or 12/12 split in fasting/eating windows.
This eating strategy does not have to be a complicated plan to implement. Simply choose the desired fasting period, eat between fasts, and workout when your body has the energy for it.
To answer further questions, concerns, or to dive deeper into a concept start from the top and read on through. It’s length but comprehensive. Everything is here for the taking. Use our knowledge and to your advantage.
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All pictures came from source 1