Whether it’s after the holidays or you’ve just been less mindful about what you’ve been eating lately, you might have come to realize that you’ve tacked on some unwanted weight. We’ve all been there, facing the prospect of a restrictive diet plan and wishing there was a better way to cut calories.
Luckily, many have found intermittent fasting to be the best solution, since it offers the ability to restrict and reduce calories without having to tightly control what they eat at all times.
Intermittent fasting has gained wide popularity for its effectiveness and flexibility. It might also be one of the simplest lifestyle changes that you can do for yourself to promote long term weight-loss. It’s used by celebrities and body-builders alike, and the only real lifestyle change that it requires is strict adherence to an eating schedule.
These intermittent fasting schedules all boil down to alternating periods of fasting and eating. Eating within a specific window of time helps you to be mindful about what you put in your body. At the same time, fasting gives the body time to repair itself between meals.
Scheduled and well-considered intermittent fasting helps with weight loss, long-term improvements to metabolic health, and a strengthened immune system.
What Is Intermittent Fasting?
Fasting, scheduled or otherwise, has been a part of human life for thousands of years, and our bodies are well-adapted to experiencing periods of time without eating.
In some cases, fasting was a necessity during times of hunger. There are also times that we fast naturally, in response to feeling sick or stressed. Additionally, fasting has also been practiced for various religious purposes all around the world, including Hinduism, Judaism, Christianity, Islam, Mormonism, and Buddhism.
The contemporary trend of intermittent fasting is meant as a way to lose weight and improve one’s overall health. You do this by adhering to an eating pattern that designates times to eat, sometimes known as feast days, and times to fast. These patterns split the day or the week into eating times and fasting times.
How Does Fasting Work?
There are two main factors that affect how time-restricted feeding and intermittent fasting can make you healthier.
The first factor is the calorie restriction that results from the limited eating times. Those who practice intermittent fasting are more likely to restrict calories and eat less within the time restrictions. This is what makes intermittent fasting an energy restriction diet. Many prefer this use of an eating pattern to dieting, which normally requires individuals to eat each of their meals using pared-down portions and counting calories.
The second component of time-restricted feeding’s health benefits has to do with the circadian rhythm and hormone balancing. When you eat, you send your body through its metabolic cycle, which determines where it gets its energy as well as how much energy it stores. This balancing relies on the fasting part of the metabolic cycle, which allows for cellular repair, efficient use of hormones, and many of the other benefits that fasting has to offer.
How Fasting Effects the Body
When we have not eaten for a while, our bodies undergo a few processes to help us repair our health. These include hormonal balancing, as well as repairing our cells and genes.
During fasting, the body transitions through three stages
1) The Fed State, also known as the absorptive or post-prandial state
During the fed state, you have just eaten. That means your gastro-intestinal tract is full and your body is fueled up. This lasts for about four hours after eating.
Your body will first use the food you just ate as its energy. In this case, it is using the glucose from those foods to power your body.
This is also when body fat storage is active, meaning that the body is busy storing away the excess energy that it doesn’t need at the moment.
2) The Fasted State, also known as the postabsorptive state
When your body is fasting, it no longer has the food that you eat to get its energy from. That means that it’s going to start burning body fat to get the energy that it needs.
The early fasted state begins a few hours after eating, and it lasts for about 12-18 hours. In this time, your body is no longer storing fat. Instead, it begins to use its stored glucose as energy.
As this state ends, the body transitions through its fuel options, such as fat, lactate, and alanine.
3) The Starvation State
Contrary to popular belief, there are few known short-term downsides to the starvation state, when fasting periods are limited to 48 hours or fewer. Entering the starvation state is sometimes referred to as “flipping the metabolic switch.” After 12-36 hours of continuous fasting, the body will have depleted its glucose reserves in the liver.
This causes the body to use other resources as fuel, including free fatty acids. The mobilization of fatty acids helps to preserve muscle mass and function. This, as a result, improves overall body composition to enhance performance and slow aging.
This process affects many parts of the body connected with the metabolic pathways, including the cardiovascular system and blood pressure, as well as the hormone system and insulin sensitivity.
It also allows for autophagy, which is part of the process of cell cleanup and repair. Generally, autophagy is a response to physical stress, making metabolic states like brief starvation or ketosis a great way to reach autophagy, particularly when these diets are paired with exercise.
The Different Intermittent Fasting Schedules
Since intermittent fasting is better characterized as an eating routine than an actual dietary change, the emphasis is on the schedule. One of the best things about intermittent fasting is its ability to put the metabolism on a regular schedule. The regularity of the schedule not only helps to form a habit that can lead to consistent weight loss, but it also means better consistent health throughout your body. This comes through in benefits such as increased insulin sensitivity and anti-aging .
Each intermittent fasting schedule represents a way of splitting a normal day or week into periods of fasting times and eating times. Most fasting schedules can be classified as either time-restricted feeding or periodic fasting.
Time-restricted feeding refers to designating a window of time each day for eating. For many, this kind of fasting is nothing new, since the majority of people have a long fast every night when they sleep.
Periodic fasting normally refers to designating a fasting day a couple of times a week, and usually refers to 24-hour fasts.
Whether you’re doing time-restricted eating, or periodic fast days with full days of fasting, it’s important to choose which times or which days of the week you intend to fast and stick to them. This doesn’t mean that you can’t amend the schedule if you find that the current schedule isn’t working out for you.
Nonetheless, once you strike on a manageable schedule, it’s best to keep going with it. This is because, the more often you change your diet, the more likely you are to drop out of a potentially strenuous lifestyle change. Building a habit such as intermittent fasting requires consistency.
The Most Popular Intermittent Fasting Schedules
We have collected a list of some of the most popular intermittent schedules and how to practice them. Keep in mind that since intermittent fasting relies on consistent routines, you can modify each of these routines to better suit your own lifestyle.
The 16/8 Method
Sometimes known as the Leangains protocol, the 16/8 method is a form of time-restricted feeding. This is the most popular and often considered the easiest intermittent fasting schedule since it extends the usual nightly fast for a few additional hours.
The eating period is shortened to an eight-hour window of time, and the body fasts for 16 hours, most of which is late and night and in the morning.
Participants choose the eight-hour interval when they may eat. This is most commonly 12-8 p.m. or 1- 9 p.m. Participants therefore skip breakfast in the morning and eat their first meal at lunch.
However, these times can be changed to allow for a later or earlier eating schedule. Some individuals choose other times that work better with their schedule or further restrict their eating window.
The 16/8 fasting schedule is one of the best for everyday functions and those who exercise consistently. If the fast is not broken before exercise, it could increase fat burning. It may, however, decrease performance during exercise or training longer than an hour.
The Eat-Stop-Eat method is a 24-hour fast, practiced once or twice a week. It is most often practiced by fasting after dinner one day until dinner the next day. In this case, the time of dinner must be consistent.
The 5:2 Diet
Similar to the Eat-Stop-Eat, the 5:2 diet is a periodic fast. Participants choose two days out of the week to eat only 500-600 calories.
This schedule has been studied extensively and is considered one of the best diets to help overweight individuals consistently lose weight. Additionally, the 5:2 diet may have a small effect on chronic pain and mood disorders when practiced in conjunction with other therapies.
Alternate Day Fasting
This is the strictest form of periodic intermittent fasting because of the increased number of fast days during the week. 24-hour fast days are interchanged with 24-hour feast days.
Alternate day fasting has been found to be just as effective for weight loss as everyday calorie restriction. Individuals who practice this strict form of fasting will typically lose between 3 and 8 percent of their body weight over a period of three to twelve months while also improving cardiovascular health and metabolic biomarkers.
One Meal a Day (OMAD)
The OMAD diet is considered a strict form of time-restricted feeding, in which the eating window is shortened to one hour a day.
Most participants take this schedule to mean that they fast for the majority of the day, and having only one meal when they can eat whatever they’d like. This is because in one hour you simply won’t be able to eat enough to compensate for the rest of the calories you would have eaten throughout the day on a regular schedule.
While this can be an extreme way to lose weight quickly, the OMAD diet is difficult. It can often lead to feelings of deprivation and binging. This is the fasting schedule that is the most likely to lead to on-again, off-again dieting which will not benefit health. Some also find this dieting behavior to be too close to some eating disorders.
What Can You Have While Fasting?
During fasting, you shouldn’t eat anything solid or of caloric value.
However, you can and should drink non-caloric liquids, particularly filtered water. Other recommended beverages during fasting periods include unsweetened coffee and tea. At this time you can also consume non-caloric vitamins and supplements.
Morning coffee drinkers should keep in mind, though, that if you’re used to drinking your coffee with breakfast, drinking black coffee can upset an empty stomach.
Some forms of intermittent fasting, particularly those that involve day-long fasting, also allow small amounts of low-calorie food during fasting. The AHA has found that eating some food (about 500-600 calories) on a fasting day has allowed the greatest weight loss and decreases in insulin resistance among overweight individuals.
However, those who are accustomed to having a few drinks in the evening should remain mindful. Intermittent fasting allows non-caloric beverages during fast time, but evening drinking will be breaking this fast, whether its beer, a glass of wine, from your wine fridge, before bed, or another night-cap. If you are accustomed to consuming calories later in the day, you might opt to move your window of eating later.
Who Can Try It?
There is no optimal weight loss solution that will work for everyone. Not only is intermittent fasting a biological choice, but it also entails a lifestyle choice, to help to regulate the body’s energy and schedules. What works well for one person may not be the best approach for another.
That being said, if you’re having difficulties managing your weight or find yourself eating with inconsistent schedules to your detriment, intermittent fasting may be a great solution for you. Ultimately, adherence to a diet is one of the most important factors to effective dieting., and if you can stick to intermittent fasting, then it might be the solution for you.
Intermittent fasting is recommended primarily for overweight individuals for its calorie restriction effects. For example, in New Zealand doctors are at liberty to recommend intermittent fasting to all people except diabetics as an energy-restriction diet.
Those who are not obese may find fewer discernable changes throughout their intermittent fasting practice. However, they may also enjoy some of the underlying benefits, such as improved heart health, cellular regeneration, improved circadian rhythms, and hormone balancing.
Who Shouldn’t Try It
There are a few physical states that put individuals at a greater risk while fasting. The following individuals are not recommended to fast:
- The National Institute of Aging warns against intermittent fasting for the elderly.
- Intermittent fasting has not been studied and is not recommended for children or adolescents. Many theorize that it may disrupt growth and metabolic development.
- Intermittent fasting is not recommended for underweight individuals or those vulnerable to eating disorders.
- In most cases, intermittent fasting is not recommended for athletes who exercise or practice for more than an hour a day.
- Women who are pregnant, breastfeeding, trying to conceive or who have experienced fertility issues should not participate in intermittent fasting.
Anyone who has found that intermittent fasting has negatively altered their health or impaired their activity should stop and talk to their doctor.
There is some research that shows intermittent fasting to be more effective among men than women. Some women report that intermittent fasting causes them to miss their menstrual cycles. If women experience amenorrhea or missed periods, they should stop their intermittent fasting schedule at the possible risk of infertility.
Benefits of Intermittent Fasting?
- Cellular Repair – Intermittent fasting and periodic fasting in particular allow for cell-based regeneration and DNA repair, which helps to improve metabolic and overall health. Cellular repair also includes a process called autophagy, in which the cells break down and remove the old or damaged proteins that naturally build up in the cell.
- Reductions in Blood Sugar and Insulin Levels – Intermittent fasting also helps to decrease insulin resistance, thus reducing the risk of Type 2 Diabetes. In short, being sensitive to insulin means that your body will be more likely to use the fuel that you give it efficiently. The body will be at its most insulin-sensitive after a fasting period.
- Hormone Balancing – When fasting, the body adjusts and balances its hormone levels to make stored body fat more accessible for burning. These hormone adjustments include an increase in human growth hormone, allowing for easier fat loss and muscle gain.
- Restrict Calories and Burn Fat – Studies have found that intermittent fasting helps with weight loss, particularly among overweight individuals.
- Improved Metabolic Health – Intermittent fasting helps to regularize the metabolism while reducing risk factors and improving other health markers.
- Chronic Pain Management – When used alongside other pain management therapies, intermittent fasting has found some success in helping to reduce chronic pain.
- Protect Against Diseases – Intermittent fasting has shown in a laboratory setting the possibility of protecting the body against a variety of diseases. Many study participants noticed a decrease in “bad” (LDL) cholesterol and lowered blood pressure, as well as reduced triglycerides. This helps to prevent heart disease. Similarly, genes that are related to protecting against diseases and overall mental longevity have been known to change and offer more protection against alzheimer’s disease.
- Stabilizes Eating Patterns – Irregular eating patterns are least favorable for achieving a healthy heart and weight. It’s difficult to find a consensus regarding when you should be eating and meal frequency in scientific studies, and the data takes us all over the place looking for the holy grail of eating patterns.
However, you can be sure that having a pattern is better than no pattern altogether. Time-restricted feeding and intermittent fasting help to solidify your eating pattern. They promote mindful eating by scheduling when and how often you eat.
- Simplifies Life and Saves Time – Fasting means eating fewer meals which can help to save time with less meal planning and less meal prepping. It can also help to save your budget if fasting times cut out some of those intermediary snacks.
For many, this also makes intermittent fasting a preferable diet plan to other calorie restriction methods, which require a lot of advanced planning to alter the diet or make sure that all available snacks and meals fall within the dietary parameters.
Additionally, other diets might leave one feeling unsatisfied in a way that makes it difficult to alter eating habits for the long term. Intermittent fasting changes appetite patterns so that eating becomes less dominant in one’s thinking.
The Drawbacks of Intermittent Fasting
Put all of the positive benefits of intermittent fasting together, and you have many claiming that intermittent fasting can be the key to a longer and healthier life with improved cognition. We do, however, lack data regarding just how long individuals who practice intermittent fasting can live, since the journals currently lack studies regarding the long-term effects of intermittent fasting.
Although there are many studies to corroborate the short-term benefits of intermittent fasting, there are currently no studies that document its long-term effects. While studies such as these are likely in the works, it will be some time before the health benefits are verified for long-term sustainable health and wellness.
One of the drawbacks of intermittent fasting is the impulse to binge eat when breaking the fast. Feast days shouldn’t be confused with binge eating. Individuals who intend to lose weight will still need to facilitate a healthy diet.
Fasting can help to regulate and control hunger and metabolism. However, eating more than you normally would on a feast day could negate many of the positive effects of intermittent fasting, while also causing worsened metabolic and appetite consequences.
It’s important to note that binging and overconsuming has been shown to be a natural or instinctive impulse, and many individuals will need to thoughtfully control this until they are used to the fasting schedule.
Those who practice intermittent fasting may also experience a range of side-effects that disrupt or impair everyday activities.
Side Effects to Watch Out For
Many people have reported that during fasting periods, they feel better and have more energy. However, it can take a long time and some personal adaptation to come to this point. Many who begin intermittent fasting will feel some discomfort until they adapt to the schedule.
To mitigate some of the side effects you may experience from beginning an intermittent fasting routine is to keep drinking plenty of water throughout the day. Also pay attention to your nutrition during fast days, as it’s still important to get your vital nutrients that help your system function.
Acceptable symptoms during intermittent fasting include:
- Hunger – In the beginning, as your body is getting used to the fasting schedule, it’s common to experience hunger during fasting periods. Once your body adjusts to the schedule, however, hunger often becomes less of an issue.
- Low Energy Levels
- Poor Mental Functioning
- Dehydration – Intermittent fasting is not a water restriction diet. All throughout your fast, you are encouraged to drink water. Low caloric beverages are allowed during fasting periods, and it’s even possible to flavor water with low caloric options, such as natural lemon juice.
During studies, problematic symptoms only appear after several days or weeks of fasting. When practiced appropriately, intermittent fasting should not have these serious adverse effects. These serious symptoms can include:
- Eating Disorders
- Susceptibility to Infectious Disease
- Organ Damage
- Cardiac Failure
How to Begin
Most people consider the biggest hurdle to beginning with intermittent fasting to be their mentality regarding meals. Because most of us aren’t raised to fast, we often consider it to be unhealthy or we assume we can’t go that long without eating.
A lot of this is in our heads, a mental barrier based on eating myths and personal experience that makes intermittent fasting more difficult. If you want to begin fasting, the first place to start is checking your assumptions and willingness to try a new experience.
If you’re ready to begin intermittent fasting, but don’t know where to begin, most people consider the 16/8 method to be the easiest entryway into fasting.
Once your body becomes comfortable with this method, you can stick with it to receive the benefits of time-restricted eating, or extend your fasting for a more extreme weight loss approach. You can move on to the 5:2 Method or the Eat-Stop-Eat fast.
Some people begin their intermittent fasting by simply skipping meals whenever it’s convenient or they don’t feel hungry. This means not beginning with a set schedule but instead starting with a practice that allows you to train or alter your appetite. This can provide some of intermittent fasting’s smaller benefits, such as caloric restriction.
However, keep in mind that if you want some of the larger benefits of intermittent fasting, such as hormone balancing, it’s important to develop the habit into a routine and rhythm that your body can understand and predict.
Best Apps to Help You with Your Fasting
Fasting applications will often pack features, such as time tracking and reminders, to keep you from missing your eating window. Many also provide calorie restriction tools and weight tracking to help you keep track of what you eat as well as when you eat, while breaking these habits down into easy to understand metrics.
DoFasting (iOS and Android) – The DoFasting application can be highly personalized to allow you to plan and record your own weight-loss goals. It has preset fasting schedules that allow you to track your window and help you to eat on time. Additionally, it has progress tracking, as well as personalized meal and workout planning.
LIFE Fasting Tracker (iOS and Android) – LIFE Fasting Tracker is a solution for individuals who would like to diet socially while being connected to a larger community of fasters. It offers a fasting tracker with data and statistics to help you review your progress, as well as an in-app community and informative articles and inspiration to help make fasting easier.
Fasten (iOS and Android) – This application helps to tie your fasting and weight-loss journey to other metrics that are very important in your life, including hydration and water intake, mood tracking, and friends to fast with and hold each other accountable.
Fasting Tracker (Android) – This is a pared-down fasting tracker that offers flexible fasting schedules while also keeping track of fasting and weight history. It works for those who want something that’s simple and easy to use.
Zero (iOS and Android) – The Zero application offers flexible fasting scheduling where you can pick from the presets or customize your own times. It tracks fasting, weight, offers statistics, and allows you to make notes on the fasts you do. In addition, it offers media, content, and studies to help you stay informed and motivated.
Other Helpful Resources and Tools
Just like with any schedule meant to stoke progress and keep you on track, one of the best resources you can get your hands on is a planner or scheduler to track your fasting schedule.
Whether you’re tracking it in a habit planner or using a printable table, a visible schedule can help you remain mindful of your eating habits and keep you from forgetting what time or day it is. The planner can also facilitate social eating meals with other people, so that you can schedule meals during a feast day without getting things mixed up and breaking your patterns.
Additionally, myCircadianClock is an application Developed by Dr. Satchidananda Panda of the Salk Institute for Biological Studies to help you participate in a study on intermittent fasting. This smartphone application helps individuals keep track of their circadian rhythm for hormone balancing, while also collecting health data to advance research on the long-term health effects of time-restricted fasting.
Are There Foods to Gravitate Toward or Stay Away From?
One rule to remember during feast times is to eat just until you are satisfied and stop before you find yourself overeating.
Ultimately, healthy food must be chosen on non-fast days, and during fasting times. For weight-loss, intermittent fasting is recommended by the American Heart Association as one part of a constellation of simple dietary changes, including eating healthy snacks prior to meals to discourage overeating and planning meals and portions throughout the day to control hunger.
Intermittent fasting among individuals not classified as obese may only offers marginal weight-loss results. Larger people will burn more calories during the day. At the same time, those who generally tend to eat less will generally restrict fewer calories by skipping a meal or two. For similar reasons, the weight loss benefits often slow down after a year of consistent intermittent fasting.
As with any diet, honing your physical composition with intermittent fasting comes down to what you eat, as well as when you eat. Certain foods, such as eating whole grains, vegetables, fruits, nuts, and even coffee are known to contribute to overall health and longevity. If you’re having trouble keeping foods around without running to the store every day, check out our food storage guide.
Similarly, entering the starvation state after a feast day of unhealthy foods, such as processed sugars, is sure to make you crash and give you unbearably little physical and mental energy while fasting. While intermittent fasting doesn’t ask you to police what you eat as closely as a calorie-counting diet, eating certain foods will multiply your gains, while eating less healthy foods will make your nutritional journey an uphill battle.
Long fasts can be more difficult to break than short fasts, and some people find that they need to ease themselves out of the fast to not upset the digestive system. Easier foods that help to break a fast include smoothies and soups, cooked vegetables, fermented foods and food containing healthy fats, such as eggs or fish.
How to Explain It to Friends and Family
Eating is such a social activity that there are certainly going to be times when you’re expected to eat with someone during fasting time. This could be with a visiting family member, a group of friends celebrating something, or a business dinner that you can’t say “no” to. These special occasions can cause a brief scheduling dilemma.
Luckily intermittent fasting, and particularly time-restricted eating, is one of the easiest diets to get friends and family on board with. When it’s not your eating time, you likely don’t even have to come to the table. That means, if you’re skipping breakfast, you can get on with the rest of your morning routine, without joining the breakfast table.
When it comes to dining with friends and family, it’s helpful to explain why you are fasting, what you intend to achieve, and even show them that you have a solid plan or schedule. This will help them to legitimize intermittent fasting in their own mind and support you. Positive support from friends or family can really make or break a lifestyle change.
If you’re receiving pushback on your fasting, here are a few ways to explain it to those around you without alienating either you or them by sticking to your choices.
- Shoulder responsibility for additional tasks or chores that may be caused by the change of schedule.
- Find other times to spend with family members if you generally rely on meals for family time.
- Make the appropriate concessions to not alienate friends and family. Try the delicious thing they made but on your schedule.
Commonly Asked Questions
“Isn’t Breakfast the Most Important Meal of the Day?”
Many people believe that skipping breakfast will actually lead to weight gain. However, when it comes down to the same amount of caloric intake, there is no actual difference between someone who eats breakfast and someone who doesn’t.
Some people have a difficult time functioning without breakfast, while others actually perform better without it. It’s up to you to know your habits and alter your schedules to help you the best. If you know that you need breakfast, you can make this a priority in your eating schedule.
“Doesn’t Grazing and Eating Frequent Meals Help to Lose Weight?”
Digesting meals does burn some calories. However, for those who really want to lose weight, it’s more important to consider proportions and how much you’re eating, rather than the frequency of your eating. If you want to graze during your eating time, the calorie burn you’ll receive is still the same as eating one concentrated meal of the same caloric value.
Grazing doesn’t actually help you to lose weight through your metabolic function or by burning extra calories. What it does is help signal to your appetite when you’re satisfied.
Eating small frequent meals can help you eat fewer calories, because it forces you to slow down, allowing your body to effectively signal when it is full. If this works with your lifestyle, there’s no reason you can’t pair it with intermittent fasting.
“Doesn’t Starvation Mode Mean that Your Body Shuts Down and Stops Burning Calories?”
Short term fasts actually increase your metabolic rate rather than decreasing it. Someone who practices intermittent fasting does not experience weight gain or metabolic slowing through starvation mode. Instead, their metabolism experiences a boost that also helps to convert muscle.
As long as your fast is under 48 hours long, you don’t have to worry about your metabolism slowing down to preserve your body mass.
“What Happens If I Miss my Eating Window?”
Missing your eating window happens to everyone now and again. It won’t ruin your progress or set you back unless you let it.
If you miss your eating window and find that you’re hungry, you should still eat and approximate what will be best to keep your ideal eating pattern. This might mean eating later than you’re supposed to, which means less time for your body to enter the fasting state.
Use your best judgment knowing yourself and your own habits when it comes to deciding whether to eat or not. Skipping another meal when you miss your window could result in an unsustainable fast. Or, you might find that you break the cycle, making it much harder to stay on track with your pattern.
Intermittent fasting is all about controlling your eating schedule. The aim is to allow your body to spend some time in the fasting state at a regular frequency. In the fasting state, the body will use body fat and other energy resources for fuel after it finishes off processing what you ate that day.
The way you get to that point and what diet and schedule you use is completely up to you. Whether you’re more interested in time-restricted feeding for its circadian rhythm benefits or periodic fasting to lose more weight and increase your willpower.
Ultimately the best fasting and eating schedule is the one that helps you succeed in your goals. This will most likely be the one that you can stick to and that fits in best with your lifestyle.