Intermittent Fasting-The Ultimate Guide

There is no diet type in this world that has stood the test of time quite like intermittent fasting has. Provided that you have enough mental toughness and clarity, intermittent fasting can be performed at any time and any place. Technically speaking, it’s not even really a diet-it’s a way of controlling your intake of food so that you can reap the benefits associated with it. Fasting can do a lot of good for your body, making it well worth your time. This is especially true if you are trying to lose weight or increase your productivity levels.

What is intermittent fasting?

While you may hear a few definitions all over the internet, there is only one true definition. Intermittent fasting is the simple act of not eating any food for a predetermined amount of time. This time can range anywhere from 8 hours to 72 hours. Past 72, the benefits start to peter out and your body will require nutrients again. For most people, not eating any food for 8-16 hours is ideal, and you can start at any time. In most cases, you will plan your fast to start or end at bedtime, since you can’t eat anything while you are sleeping. During a fast, the only source of energy you are allowed to consume is water or safe zero-calorie beverages (more on water’s benefits later).

Intermittent fasting can feel difficult if you are sensitive to the feelings of hunger. Hunger is really the only major hurdle that stops most people from committing to this diet type. It is an uncomfortable feeling that we tend to try and cure immediately, similar to boredom.

It is important that you start with baby steps if you are a beginner. This can be starting with a 4 hour fast one day, then gradually working up to 8, then 12, then 16. That way, you give your body a chance to adapt to the stresses of hunger.

Eventually, hunger will dissipate because your body will understand better how to leverage its resources to sustain a fast. Because fasting is a natural, evolutionary survival tactic, most people are able to fully adapt in as short as one week.

Why should you try intermittent fasting?

In today’s modern world, our access to food, water, and other amenities is easier than it has ever been. We can easily leave our homes at any point in the day to stock up on groceries or get a bite to eat at a restaurant. Healthcare and physical therapy is easily accessible for most people. There are plenty of gyms around to fulfill our need for exercise, as well.

We as a species have solved an incredible number of complex problems. This is a great blessing, because in conjunction with the internet and our access to free information, life in general today is effortless compared to how it was in the past. We can enjoy meaningful work and pursue pleasures without having to worry about survival too much.

However, the modern world we live in can also be a curse. Because filling our bellies is sometimes too easy, we might find ourselves overindulging a little too much. Obesity rates, especially in the US, are much larger compared to how they were 50 years ago. It was once so high that one might wonder if there was an obesity-causing virus that created this. In fact, it’s not just obesity-there has been an epidemic of health issues in people recently, which includes diabetes, stroke, heart disease, neurodegenerative diseases like Alzheimer’s, and more. The death rate in 2022 was 13.8% higher than in 2012 (courtesy of usafacts.org), and obesity rates in the US alone have tripled since 1964, with about a third of Americans today having an obese BMI.

How does fasting solve these physical health challenges?

Intermittent fasting can serve as one solution to these problems. Fasting gives you the ability to control your eating habits in a way that is natural for the human body. Thousands of years ago, our ancestors had to work for their food, since businesses that serve food did not exist back then like they do today. Ancient humans had bodies that were extremely well adapted to periods of famine and drought. When they did find food, they had to conserve it so that they could feed themselves and their families as much food as possible in a small timeframe. After eating, they usually did not eat anything else for several days. As the centuries passed, tribes and civilizations formed to make survival easier, since we humans are strongest when we form teams and communities.

Intermittent fasting in today’s world gives you an enormous competitive advantage over the people around you who don’t practice it. If you are constantly eating, you don’t give your stomach a chance to stop the act of digestion. By leaving your stomach empty for a long period of time, you allow your body to focus its energy in other areas, which is an amazing thing. When digestion stops, your body is able to flush out toxins, redistribute and use excess fat stores, pass stool through the large intestine more easily, redirect energy to the brain to improve mood and focus, and much more! These benefits make your body much more resilient to illnesses and weaknesses.

The many benefits of intermittent fasting

The benefits of fasting are paradoxical in nature because the body repairs itself faster by not eating. When you fast, however, you must know how active or sedentary you are as a person. If you work a strenuous job or you are moving all day (for example, hiking up a mountain), then intermittent fasting may not be a good thing to do in those scenarios. It is best to do intermittent fasting if you have a consistent exercise routine and work schedule. We will discuss intermittent fasting strategies in a later segment of this post.

With that being said, intermittent fasting has no shortage of great, life-changing benefits. Here are the most important and obvious benefits. (IF=intermittent fasting)

• IF makes weight loss much easier to accomplish. First off, the most obvious and impactful benefit of IF is to speed up the process of losing weight. Calorie restriction forces the body to use excess glucose and fat stores for survival. Intermittent fasting can make you lose as much as a pound a week if you exercise vigorously. Everyone wants a lean, attractive body, and mastering IF can help you sculpt a physique that you can be proud of.

• Morning fasting significantly improves brain focus and concentration. Once your body adapts to fasting, your morning productivity levels will skyrocket. This is because fasting increases your body’s BDNF (brain-derived neurotrophic factor), which is a protein that helps brain and nerve cells survive and function. Try not eating anything at all during the morning (through a method like the 16:8 window, more on methods later) and then work on a cognitively demanding task. You will be amazed at how clearly you will be able to think and focus!

• IF lowers insulin levels and improves insulin sensitivity. During a fast, your body uses its blood sugar stores for energy. This can result in fat burning and making stored body fat more accessible for survival.

• Your cells repair themselves and clean out dead cells more easily during intermittent fasting. Autophagy is a term used to describe a bodily repair mechanism where damaged or dead cells are removed or recycled. When you do a fast, your body has more time to focus on this process because it doesn’t have to worry about digestion and the transfer of nutrients.

• Fasting over a long period of time changes how your genes express themselves. Genes serve as your body’s record of the past, since you are a product of the generations that came before you. Genes are meant to express certain behaviors and traits that your parents had. But intermittent fasting done over a long period of time (usually several months) can allow you to control gene expression positively. For example, if your family has a history of cancer, diabetes, or mental health issues like depression, IF can prevent these illnesses from happening. This was proven in a lab experiment on mice conducted by Salk Researchers. They also found that IF increases longevity by slowing down the aging of the physical body and by strengthening the immune system.

• IF increases levels of HGH (human growth hormone) in the body. HGH is responsible for fat loss, muscle gain, height growth in children, cellular repair, and more.

• IF improves cardiovascular health. Intermittent fasting influences how well your body manages its blood transport and storage. This can lead to a reduced risk of heart disease, stroke, type-2 diabetes, high blood pressure, and lower levels of cholesterol.

• IF reduces inflammation and improves conditions associated with inflammation. Inflammation is the immune system’s response to an outside irritant. This is normal for the body to do, but sometimes an unhealthy diet or genetics can cause inflammation to get out of hand. For example, asthma, multiple sclerosis, Alzheimer’s disease, allergies, stroke, and arthritis can stem from the body’s flawed ability to handle inflammation. Luckily, intermittent fasting has been shown to regulate inflammation by changing gene expression, as said earlier. It also helps the body produce more white blood cells.

• IF is likely to improve sleep quality over time. In the beginning, sleep may feel difficult during IF because you will likely feel episodes of hunger and nausea. After one week, however, as your body adapts, IF will greatly improve your sleep quality, and may even help with insomnia. This is because fasting increases production of a neurotransmitter known as orexin-A, which controls daytime alertness. Orexin-A levels dip during nighttime, so this means that your body will feel more alert during the day and will enjoy restful sleep during the night. Sleeping better at night brings a whole slew of new benefits such as increased HGH production and better muscular development.

Risks associated with intermittent fasting

Intermittent fasting has no long-term risks. However, for diet beginners or sensitive people, they can experience some unpleasant side effects if their bodies are not used to it. These side effects can be very uncomfortable or debilitating. They usually only last about a week or two. While these issues are only temporary, it is still important that you know what these issues are so that you are prepared to deal with them if they come up. These side effects include:

• Hunger. Hunger is a normal part of the intermittent fasting process, and it is especially noticeable in the first week. Short-term feelings of hunger subside after a few minutes as your body pulls energy from its available fat stores. If your body has a hard time staying satisfied and you constantly feel hungry, then it is likely you aren’t getting enough nutrients in your diet. Eat clean, single-ingredient foods like eggs, whole wheat bread, chicken breast, vegetables, salmon, nuts, and Greek yogurt. These foods ensure that your body will be able to hold out a fast as you work your way up to longer fasting windows.

• Minor fatigue. Depriving your stomach of nutrients for a period of time can be quite jarring the first time. As a result, your body may feel jittery or sluggish. When this happens, don’t be afraid to cut down on your intermittent fasting windows, or eat a snack that is high in protein such as an energy bar or beef jerky.

• Insomnia. In rare cases, intermittent fasting can cause insomnia if the feelings of hunger prevent you from falling asleep and staying asleep. People who already suffer from sleep disorders may find that intermittent fasting can easily exacerbate these disorders. If this is the case, stop fasting immediately and consult a doctor. In most normal cases of insomnia, however, you can remedy this issue by eating your most calorie-dense food 3 to 4 hours before bedtime. A great, filling dinner can work wonders for your sleeping patterns. Also, make sure you sleep in a cold and dark room (about 68-70°F and no light whatsoever).

• Nausea. Daytime nausea may occur as a result of your body lacking nutrients. Hunger is normal and okay, but nausea isn’t. Consume nutrient-dense foods and plenty of water to prevent this from happening.

• Headaches. I’ve never gotten headaches while fasting before, but it seems that this is a rather common side effect to fasting. If you do get headaches, it is most likely because your sleep quality isn’t good. If you have a noisy family or you are a night owl, it can be difficult to get a good night’s rest.

To enhance your sleep quality, buy noise cancelling headphones or black-out curtains if you need them, and make sure your room is the right temperature so you can stay asleep. If your room is too hot or your body temperature is higher, your sleep will ultimately be worse overall.

Headaches while fasting may also occur as a result of strenuous exercise. Before exercising, make sure your body has the nutrients it needs to support the fast. It may also be helpful to end a fast directly after exercising so that your body can recharge as it enters an eating window.

Best foods to eat for a successful intermittent fasting schedule

Truthfully, you can eat whatever you want during your eating windows. The only rule of intermittent fasting is to commit to timeframe where you consume nothing but water. However, there are certain foods that help you accomplish our fast much, much easier.

Foods that are high in lean protein, fiber, vitamins, and minerals are your best bet to have during intermittent fasting. This is because these foods help you feel full for a long time while also ensuring that your body is getting an adequate supply of essential nutrients. These foods include:

• Vegetables such as broccoli, spinach, potatoes, cauliflower, and butternut squash.

• Fruit, such as avocado, apples, bananas, oranges, kiwi, mango, grapes, and blueberries.

• Whole grains such as fortified whole-wheat bread, barley, quinoa, oats, and brown rice.

• Any nuts and seeds, like almonds and pumpkin seeds

• Legumes like beans, lentils, and chickpeas

• Non-sugary dairy like cheese and Greek yogurt

• Clean, lean meats like steak, poultry, and seafood

Which intermittent fasting method should you choose?

The intermittent fasting method you choose should primarily relate to what goals you are looking to accomplish. Don’t focus on the benefits too much and instead focus on your objective. People choose intermittent fasting for a variety of reasons. These reasons include, but are not limited to:

• Weight loss for health reasons
• Fat loss, which results in a more lean and attractive body
• Increasing work productivity, especially in the morning
• Changing your body’s gene expression to reduce or eliminate chronic life diseases
• Training for an athletic event like a swimming competition or marathon
• And many more

There are plenty of good, valid reasons for wanting to engage in intermittent fasting.

Once you have identified your primary goal, the next step is to choose a method that aligns closest to your goal, and stick to it for as long as you need to. IF is not meant to be done your whole life, you just have to commit for several months to see great results. It is ultimately up to you how long you stick with this diet type. Some people need more time to adapt to it, and that is normal. Just remember the risks of intermittent fasting and be mindful of your body’s reaction to this change in lifestyle. If you are not used to fasting, then you need to start small and work your way up to better, more valuable IF methods over time.

Here is a list of time-tested and reliable intermittent fasting methods. All IF methods, when executed properly, can bring you the great benefits shown earlier in this post.

*IMPORTANT NOTE*-Remember to drink plenty of water. Intermittent fasting will be useless to you if are not staying hydrated. The average adult male needs about 3.7 liters of water per day, while women need about 2.7 liters.

Fasting method	Timeframe	Days spent fasting per week	Helpful for:
16:8 Daily Method	16hr fast, 8hr window	Every day	People with free time. Also great for productivity
The 5:2 Diet	2-day calorie restriction	2 days	People who lack time
Eat-Stop-Eat	2-day full fasting	2 days	People who have a mix of strenuous and sedentary days
Alternate-Day Fasting	3-day calorie restriction	3 days	For people who value predictability and consistency
Warrior Diet	20hr fast, 4hr window	Every day	People who are athletic and have plenty of money to buy quality foods

16:8 Daily Method

This is the most common IF method, and it is simple and reliable. You fast for 16 hours per day and eat for 8. Simple, right?

Assuming that you sleep for 8 hours a day, you can essentially plan for your fast to end 8 hours after waking up, or directly after waking up. This method brings you easy control over when exactly you want to fast. For example, I like fasting for the first 8 hours of my day so that I can tackle my highest priority tasks first thing in the morning, when my energy level is highest. This is great if you need to increase your focus and productivity. After my work is done, I can go exercise for an hour, and then I end the fast directly after. Because sleeping forces you to fast for 8 hours, the remaining 8 hours doesn’t seem so bad.

Your window of time doesn’t have to be split between your periods of sleep, by the way. Some people like to eat a massive, nutrient-dense breakfast first thing in the morning, and then initiate a fast directly after. It’s important to choose an eating window that works for your schedule and your body.

The 5:2 Diet

This method involves eating normally for 5 days, and then purposefully restricting calorie intake to 500-600 for the remaining two days. These 2 days may or may not be consecutive.

For busy people, this is a convenient IF method to do, since you only need to plan your fast for 2 days out of the week. It can help with weight loss, but you have to be careful not to eat too much on the 5 normal days to compensate for the 2 fasted days.

Look for foods that give you the highest nutrient value while being low in calories. Examples include raw veggies like carrots, cucumbers, and broccoli, and fresh fruit like watermelon and grapefruit. Non-fatty seafood like cod, shrimp, and oyster are excellent to have for protein.

Choose the 5:2 diet if you don’t have much control over your time. For example, if you work long hours at a full-time job, it is incredibly helpful to not have to worry about your diet during your working hours, then focusing on your fast for the 2 remaining days. If you manage your calories right, you will find that this a great intermittent fasting method; it is reliable and convenient for most people.

Eat-Stop-Eat

This IF method is like an extreme version of the 5:2 diet. Instead of restricting your calorie intake for 2 days, you abstain from calories entirely. So you basically fast for 24 hours two times a week. This method became quite popular a couple of years ago, but it has been used for much longer.

Eat-Stop Eat is great if you have 5 busy, strenuous days every week, but have 2 sedentary days where you don’t do much. On those two days, you may only consume water or any other zero-calorie beverage like lemon juice or decaf tea. A full 24-hour fast jolts your brain into high gear like electricity, which increases your metabolism. Due to the sudden stop of calorie ingestion, Eat-Stop-Eat forces your body to adapt to intermittent fasting very quickly. If you aren’t afraid of hunger and don’t regularly suffer from nausea, this is a great IF technique to try.

Also, try not to fast for 48 hours straight. That will almost guarantee you will feel miserable. Split your fasting days so that they are away from each other.

Alternate-Day Fasting (4:3 Diet)

Alternate-day fasting is a variation on the 5:2 diet with similar rules. But, instead of restricting calories for 2 days per week, you instead do 3 days.

What’s great about the 4:3 diet is that it’s easy to find a consistent rhythm to your dieting efforts. By restricting calories every other day, you will find it easier to not only stay disciplined, but also figure out what to buy at the grocery store.

However, the 4:3 diet does come with some risk. Restricting your calories to just 500-600 for 3 entire days a week can potentially be dangerous. As such, you should look to follow the diet for a single week and see how you feel about it. There are 2 remedies to consider if you are struggling with this diet method.

One, you can consume 500-600 calories for two days, then look to eat 1200 or so calories on your third day. That way, you can give your body a chance to sustain the nutrients it needs, while still being in a caloric deficit. And two, you can try consuming 300 calories over your daily limit on the 4 days where you don’t fast. This ensures your body has enough nutrients to sustain the fast. All in all, the 4:3 diet is a reliable but risky intermittent fasting method to try out.

Warrior Diet

Similar to the 16 hour fast, 8 hour eating method, the warrior diet is a more extreme version of typical intermittent fasting strategies. It involves fasting for 20 hours a day, and then consuming as much clean food as you can for the last 4 hours of the day (usually nighttime).

This diet aims to match the eating patterns of ancient warriors during times of conflict. They would eat very little during the day (combat time) and then feast at night (rest time). The warrior diet is said to be based on belief and observation, not science, so its effectiveness as an intermittent fasting strategy is questionable at best.

The 20-hour fasting period you undergo in this method has a few rules in particular. You can only eat dairy and plant foods during this fasting window, and you can’t eat large amounts of them. So a couple of hard-boiled eggs and a cup of fruit, for instance, is ideal. Then, during your 4-hour eating window, consume as much protein-rich food as you can, such as meat, cheese, quinoa, lentils, seafood, pizza, etc. You can technically eat any food you want, but unprocessed, organic foods are strongly encouraged.

The results you get from this diet work better if you perform some type of daily physical exercise. So during your fast, you can go for a run, lift weights, or do calisthenics, and then you have your nighttime feast to look forward to at the end of the day. If you are active and you are able to buy lots of filling, protein-rich foods, the warrior diet can definitely help with weight loss and enhancing your overall energy levels. Don’t forget to consume lots of water during the fasting windows of extreme IF methods like the warrior diet or the 4:3 diet.

How to Create A Consistent Intermittent Fasting Routine: Structure and Guidelines

IF schedules are highly variable and depend on a lot of personal factors. How much time do you have in your day, and how much of that time is dedicated to exercise? Some people work incredibly strenuous jobs like landscaping, firefighting, or warehousing. Yet, other people work sedentary jobs where you simply sit most of the day, like office jobs. If you have more free time throughout your day, you may already have an exercise routine.

The key is to create an IF routine that ensures you are getting the proper nutrients at the right time. If your schedule is more predictable and consistent, then simply use one of the intermittent fasting methods discussed earlier. Other than diet, though, it really just comes down to tracking your calories and getting some exercise in.

Try to time your eating windows so that they end when your body requires nutrients. This could be ending your fast right after your daily workout, or before you head off to work a strenuous job. For sedentary jobs, you should end the fast after your shift. Create a personalized fasting timeline so that you can write down a daily schedule. This helps you stay disciplined for your fasting routine, which is important!

Experiment with Written Schedules

Here is a sample table that illustrates the fasting schedule of an office worker (sedentary). This table assumes an average male with a slightly high BMI (5’9″, 195 lbs) who works a sedentary office job. He works Monday through Friday, and starts getting in a 30-minute workout every day after work. His main goal is to lose weight using the 5:2 method, since his schedule is quite predictable. He eats a healthy mixed diet comprised of lean meat, eggs, nuts, fruits, and veggies. (Note that sitting at a desk burns around 75 calories per hour.)

Office Worker (5:2 Method)	Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Weekly Total
Calories in	580	2,200	2,050	1,910	2,360	2,070	520	11,690
Calories Out	2,080	2,000	1,870	2,070	1,920	2,300	1,850	14,090
Net calories gained/lost	-1,500	+200	+180	-160	+440	-230	-1330	-2400

From this table, we can see that disciplined fasting builds up over time. If this office worker follows this plan for multiple weeks, the calories lost will compound over time. This will result in the man losing weight. Naturally, the human body tends to use up its fat stores first, so he will become leaner over time. This illustrates not only the practicality of intermittent fasting, but also the power of compounding as it relates to daily life.

People with more active lifestyles will require more calories per day. Without the extra calories and nutrients, your body’s energy levels will suffer.

Remember to create a routine that works for you and your body. As your body adapts to a fasting lifestyle, you can work on eating better and cleaner foods, and increase the time you spend fasting. No fasting schedule should remain static, and you should look to iterate on them either weekly or monthly.

Summary

Intermittent fasting is a completely natural and effective way of reducing body fat and improving energy levels. No matter what age or gender you are, anyone can gain at least some benefit from doing it. After all, our bodies are evolutionarily adapted to surviving on low levels of calories and essential nutrients.

By now, you should have a sufficient level of knowledge of what intermittent fasting methods you can use. You choose the methods that provide the kind of benefits you want in your life. It is up to you to experiment and iterate on your own intermittent fasting schedule. Stay disciplined and consistent, and you will likely feel and look much better for years to come.

Remember, intermittent fasting isn’t for everyone. For some people, they will have to make an extra effort to avoid overeating or indulging in sugary foods. IF works a lot better when you combine it with other healthy lifestyle habits like exercising and meditation.