There are many ways to incorporate a fast into your lifestyle. Whether you are looking to burn fat, lose weight, or just promote a healthier lifestyle, regular fasting can help you achieve your goals. Intermittent fasting, also known as periodic fasting and interval fasting, is becoming a popular fasting method.
For good reason. Periodic fasting is a highly effective fasting technique. It is also flexible and personalized. With periodic fasting you can plan your fasting schedule according to your preferences. You plan your fast based on what fits best with your schedule and activity level.
Periodic fasting is a way to harness the health benefits of fasting without having to significantly modify your life around periods of prolonged fasting. As long as you adhere to the system, you will see results.
We will get to the details. First, what is periodic fasting?
What is Intermittent Fasting?
Intermittent fasting is a fasting technique that involves dividing your days (24 hours) between periods of eating and periods of fasting.
It is more than just skipping meals. You choose to eat during specific periods and then fast in between. The idea behind intermittent fasting is to eat all of the calories and nutrition you need during your feeding window and then fasting – aka not eating any calories, during the remaining fasting window.
Intermittent fasting: divide your day between of eating and periods of fasting
You decide how to divide the periods of eating and fasting. Here’s the trick. You need to stick to your feeding and fasting windows in order for the periodic fasting to work. You will need to maintain fasting windows of at least 14 hours at a time. During this period you consume no calories at all.
The benefit of intermittent fasting you can set your intervals. You can fast and eat in one 24 hour period or you can take much longer intervals. For example, you can stretch the intervals out to include entire days of the week so that you are eating freely for 24 hours and then fasting for 24 hours.
The benefits of intermittent fasting happen as you cycle between eating periods and fasting periods over prolonged periods of time. You can even adopt periodic fasting as your permanent eating pattern. You might call this an intermittent diet.
Because the effects of intermittent fasting are highly individualized, you may have to experiment with different schedules of eating and fasting to see what works best for you. How you respond to the fast and your other lifestyle considerations will ultimately guide you. Let’s look at some examples of interval fasting.
Examples of periodic fasting techniques
There are many different variations of the intermittent fast. The primary differences have to do with the period of time allocated between eating and fasting. Some people also include some dietary restrictions during the eating periods.
Typically, dietary restrictions are included to accelerate weight loss. Specifically, fat loss. We will get to why this works later. First, some common variations on periodic fasting to consider.
Intermittent Fasting is all about time
Intermittent Fasting techniques: the 8/16 program
The 8/16 (eat/fast) periodic fasting technique is one of the most common. This is the least intrusive intermittent fasting technique as it includes a feeding period of 8-10 hours and a fasting period of 14-16 hours. The 8/16 approach is simple and consistent. Every day of the week you eat for an 8 hour window of your choosing and then fast for the remaining 16 hours. For women, the eating window can be longer. So the schedule is 10/14 (eat/fast.)
The 8/16 system assumes that your diet is generally healthy and nutritionally balanced. It does not require specific dietary restrictions. In other words, the benefits of this fasting technique are largely due to the timing of meals. While a healthy diet will greatly improve your results, the emphasis is on the timing. You have to stop eating at the end of your eating window.
The advantage of this approach is that you can schedule the 16 hour fasting window to include sleep. So you are really only fasting for 4 hours before bed and 4 hours after you wake up.
Intermittent Fasting techniques: the 4/20 program
A more advanced form of intermittent fasting includes a fasting window of up to 20 hours, every day. Your feeding window is only 4 hours per day. As such, you have to plan your meals and meal times so you can get all of the nutrition and calories you need during this short window.
Interval fasting: You decide how to divide the periods of eating and fasting
Most people schedule their feeding window around dinner time. The idea is to eat one huge meal in the evening in order to refuel and recover during sleep. During the more active daytime, your body will be forced to burn fat for energy. Hence all of the fat loss.
This approach requires more discipline and planning but can also be very effective, particularly in the short-term. People with high amounts of body fat often see rapid fat loss even early on in the program.
An alternative version of this approach is to include light snacks during the 20 hour fasting period. Some people feel better if they eat small amounts of fruits and vegetables, juices, or simple proteins a couple of times during the day. It is really up to you to determine what is best for your body.
Intermittent Fasting techniques: the 5/2 or “24 hour fast”
The 5/2 periodic fasting program is based on a much longer interval. The idea is to eat normally throughout the feeding days and then pick one or two days per week when you will fast for the entire day. You will fast during the entire fasting window of a full 24-hour period. Ideally, you would fast two days per week.
Intermittent fasting, fasting window of 24 hours
The 24 hour fast can be challenging for many people. But some people find that it is easier to just go without food for a longer period of time, but less frequently. This approach can work well for those who have certain days of the week that are either particularly busy, a sabbath, or day of rest. Like all of the approaches to periodic fasting, consistency is key.
24 hour fast benefits are similar to other intermittent fasting techniques. There is some evidence that 24 hour fast benefits are greater than shorter fasting techniques in the areas of anti-aging and anti-cancer.
Intermittent Fasting techniques: alternate day fasting
Alternate day fasting is an intermittent fasting program that includes full days (24 hours) of normal eating alternating between full days (24 hours) of fasting. It is similar to the 5/2, but the week is split evenly between eating days and fasting days.
Most people that try the alternate day fasting approach have a goal of weight loss. But there are also a number of benefits associated with regular, prolonged periods of fasting. If you are already physically active, you may find this approach to be too draining.
Other Considerations with Periodic Fasting
While many of these variations offer similar benefits, the longer fasting windows often require a more disciplined approach to eating and nutrition. The longer the fasting period the more potential for disruptions in physical activity levels, social and work schedules, and general lifestyle.
Intermittent fasting: Eat healthy and nutritious
While the benefits of intermittent fasting are optimal when eating whole, healthy, and nutritious meals, intermittent fasting can still be effective even when occasionally consuming less-than-ideal food sources, aka “cheat foods”.
The different approaches to intermittent fasting can all include other dietary restrictions if you desire. But part of why intermittent fasting is so popular is because you can realize the benefits without having to severely restrict your diet. We recommend that you try one of the programs for a few weeks before you incorporate other dietary changes.
Gender differences
Women tend to respond better to the shorter end of the fasting period, while men benefit from the slightly longer fasting period.
Because periodic fasting triggers numerous hormonal responses, maintaining a consistent schedule is essential. Women are also more sensitive to these hormonal fluctuations than men, which is why the shorter fasting period is recommended. It is also why women should gradually incorporate the intermittent fast over a few weeks. Some women find that an intermittent fasting regimen that involves 3-4 days per week is adequate.
Intermittent fasting: You can still eat breakfast. Perhaps just later in the day.
Breakfast and sleep
If you regularly skip breakfast, you are already quite close to an intermittent fast. In fact, the notion that “breakfast is the most important meal of the day” is the antithesis of the intermittent fast. Skipping breakfast is the most effective way to achieve the 14-16 hour fasting period.
Additionally, there is growing research that appetite has a natural rhythm similar to the circadian rhythm of sleep. This suggests that our appetite has natural peaks and troughs. Thus, our natural cycle of hunger is not biologically tied to the timing of our traditional meal times. Breakfast is a perfect example. Some research indicates that a natural trough in appetite occurs around 8 AM.
Speaking of sleep, getting 8 hours of sleep, skipping breakfast, and eliminating nighttime snacks will get you through the 8-10 hour fasting window. Conversely, the 8-10 hour feeding window is adequate to comfortably consume the calories and nutrition you need to function optimally.
How Does Intermittent Fasting Work?
Intermittent fasting is for more than just weight loss or to lose body fat. Fasting over consistent periods of time, aka interval fasting, is associated with many health benefits. Further, it is not a “diet” but rather an eating pattern, thus the discipline is focused on time and not calories.
Burn fat, not sugar with interval fasting
The benefits of an intermittent fast come from the cyclical intake of calories. Withholding food for prolonged periods of time conditions your body’s natural energy cycle to utilize calories from food more efficiently. This means that periodic fasting will improve your body’s ability to convert food directly into energy instead of storing it as fat.
Periodic fasting: Plan your fasting periods around sleep
Your body is efficient. It will find the energy it needs. So when dietary energy is not available, like when you are fasting, your body will recruit fat stores for energy. The process of your body converting fat into energy is called ketosis. This ketogenic state is the technical term for ‘fat burning’, which is part of why periodic fasting is so well known for weight loss.
When you are in the fasting period your body has to use up it stores of glucose (sugar). When glucose runs low, your body will burn fat for energy. Traditional eating patterns rarely force your body to burn fat. When you are eating almost constantly throughout the day, you are running almost entirely on glucose for energy. Even worse, excess glucose (sugar) is converted into fat.
Intermittent fasting works to break your dependence on sugar and retrain your body to burn fat.
Intermittent fasting also offers many indirect benefits. Periodic fasting often result in fewer overall calories consumed. By limiting the hours of the day when food is consumed, you eliminate habitual snacking. Because your feeding window is limited, your meals are often closer together in time. This means you will feel more full and thus eat less in subsequent meals.
For more information on breaking your addiction to (or, cravings for) sugar, see our related post on How to Stop Sugar Cravings with Bitter Substances.
Timing is Everything with Interval Fasting
The value derived from periodic fasting depends less on when the fasting and eating windows occur, than on the consistency of duration and timing of those windows.
Intermittent fasting can be as simple as no food after 8 PM and lunch at noon the following day. If you tend to wake up hungry – or just happen to like breakfast, you can still maintain an intermittent fast by shifting the eating window earlier into the day and stop eating by 4 PM.
With interval fasting you choose your schedule
Tips for intermittent fasting success
Periodic fasting can be seem daunting. But you can achieve your goals by simply following the timing according to the fasting plan you choose. Regardless of which fasting approach you ultimately choose, there are some things you can do to improve your experience. Here are some things to keep in mind when starting your periodic fast:
- Drink plenty of water. Hydration is always important part of health. But when you are fasting, drinking plenty of water will help you feel full. Also, when you burn fat you use a lot of water. You will need to drink more water than usual.
- Get your electrolytes. Along with hydration, proper electrolyte balance is important while fasting. Electrolytes are the minerals and salts that you need for all basic functions. When you lose water you also lose salts. You will need to make sure you are eating foods that supply enough sodium (salt), potassium, magnesium, and calcium. There are also many electrolyte supplements available.
- Use Sleep & Get Sleep. Plan your fasting periods around sleep. Sleep is essential for overall health. It is also when you replenish your hormones.
- Pick busy days/times for fasting. Staying busy will help keep your mind off of eating.
- Redefine what it means to fast. Internalize fasting as healing or resting and not as starving or withholding. Your mental state is a very important part of a successful fasting program.
- Exercise. Incorporate regular physical activity into your schedule. You will get the best results out of your fast when you include exercise. It doesn’t have to be intense, just regular.
Regular physical activity will drive results of intermittent fasting
The Health Benefits of Intermittent Fasting
Health benefits associated with periodic fasting include decreased risk factors for diseases like diabetes, cardiovascular disease, and cancer. Previous research indicates fasting can have a beneficial effect on patients with diabetes and cardiovascular disease.
Intermittent fasting has also been shown to help reduce cholesterol levels in pre-diabetic people, affect the process of inflammation and even trigger positive immune response via stem cell regeneration.
Intermittent fasting has been linked to longevity and a reduction in neurodegenerative disorders like Alzheimer’s and Parkinson’s. The 5/2 or 24 hour fast benefits indicate the most significant impact in the areas of longevity and cognitive health. Initial research is encouraging, but human research is still a long way from proving out the mechanisms of this relationship.
From a purely dietary perspective, intermittent fasting has been shown to promote weight loss and significant reductions in blood sugar and insulin levels. Periodic fasting has also been associated with a drastic increase in human growth hormone.
Final thoughts on intermittent fasting
You should always discuss any eating regimen that restricts calories or alters your eating pattern with your healthcare practitioner. This is particularly important if you have ongoing health concerns like diabetes. These fasting techniques are also unsuitable for children or the chronically ill.
The benefits of intermittent fasting or other calorie restricting dietary plans are most pronounced when accompanied by regular, moderate physical activity.
Exercise will also keep your body from adjusting to the state of reduced caloric intake. This adjustment is part why many people hit those frustrating weight loss plateaus.
While the many benefits of intermittent fasting are far from guaranteed or even fully proven, the technique has a lot of potential. So if you are looking to jump-start a holistic approach to health and wellness, give it a try to find out for yourself.
