Luisa Torres, PhD
Luisa is a science communications manager at LifeOmic. She is a neuroscientist and science writer covering topics related to aging, metabolism, and brain health.
Luisa Torres, PhD
Luisa is a science communications manager at LifeOmic. She is a neuroscientist and science writer covering topics related to aging, metabolism, and brain health.
Intermittent fasting involves avoiding calories for a period of time. It is a simple way to control your weight that doesn’t require you to follow a specific diet, count calories, measure food, or follow other complicated rules. Intermittent fasting benefits include weight loss, improved insulin sensitivity, improved blood sugar control, reduced blood pressure, reduced inflammation and increased autophagy. Although it’s not a diet, you can get the most benefit from intermittent fasting if you focus on eating natural foods most days of the week. You should also limit your intake of meals or snacks that are processed or high in sugar.
There are many intermittent fasting methods you can try. We’ll talk about some of the most popular here. Use this guide to create an intermittent fasting plan that works for you!
What intermittent fasting schedule should you follow? Consider the following 5 categories:
Time-restricted eating | One meal a day (OMAD) | Alternate Day Fasting | 5:2 Diet | Extended Fasting
Time-restricted eating
What is it?
Time-restricted eating involves consuming all of your meals within a period of 4-12 hours in a day. For example, you could choose to have your meals and calories between 8 am and 6 pm.
How to do it
There are many ways to practice time-restricted eating. Here are the most popular schedules:
Intermittent fasting schedules: Time-restricted eating
Time-restricted eating, 12/12
This intermittent fasting plan involves eating as you like for 12 hours and then fasting for the next 12 each day. This is usually done as overnight fasting. For example, finish dinner by 7pm and have breakfast at 7am the next morning. Don’t take in any calories after dinner until breakfast. This is a great way to ease into intermittent fasting. Finishing your meals a few hours before bedtime is especially important as it gives your gut a chance to rest.
Time-restricted eating, 14/10
This intermittent fasting plan involves eating as you like for 10 hours and then fasting for the next 14 each day. All that’s required in this plan is to delay breakfast a bit. For example, finish dinner at 7pm and have breakfast at 9am. You’ll have to endure a couple of hours of hunger pangs every morning until breakfast, but it’s pretty easy to do and you will get used to it over time. This schedule is the logical next step after mastering 12/12 fasting.
Time-restricted eating, 16/8
This intermittent fasting plan involves eating as you like for 8 hours and then fasting for the next 16 each day. This is a fantastic long-term intermittent fasting goal for most people. It’s done most easily by having an early dinner (e.g. finish by 6pm) and a late breakfast (e.g. 10am). Yes, you’ll have to learn to ignore your stomach growling a bit in the mornings, but even that fades over time. If you’re not overweight or perhaps mildly so, this plan will help you gradually shed a few extra pounds.
Time-restricted eating, 18/6
This intermittent fasting plan involves eating as you like for 6 hours and then fasting for the next 18 each day. This plan is popular among serious intermittent fasting practitioners. Many of them skip breakfast altogether and eat two meals a day. An example schedule is finishing dinner by 6pm and not eating again until lunch the next day around noon.
Health benefits of time-restricted eating
Weight loss
In the only long-term study (1 year) of time-restricted eating conducted to date, those who ate reduced calories within an 8-hour window dropped 9% of their body weight after 12 months, while those who cut calories without the time restriction lost 7.2%. These changes in weight were not significantly different. Most other studies of time-restricted eating show 3-4% weight loss within 8-12 weeks.
Other benefits
Time-restricted eating and, intermittent fasting in general, is particularly beneficial if you eat your meals before sunset. Not only does this help you eliminate bad habits like late-night snacking, but it improves your sleep and blood sugar control. Over time, time-restricted eating can lower blood sugar levels, make you more sensitive to insulin, reduce oxidative stress and lower blood pressure.
Time-restricted eating could also reduce your risk of breast cancer and breast cancer recurrence.
Who is time-restricted eating for?
Normal weight or slightly overweight people looking for an intermittent fasting style they can adopt for life.
One-meal-a-day (OMAD)
What is it?
This intermittent fasting method generally involves skipping breakfast and lunch while packing all calorie consumption into a 1-2 hour window or single meal at dinnertime. As with all intermittent fasting plans, it’s best if you can finish your meal a few hours before going to bed. Although it sounds hard, many people practice it several days a week, and settle into this schedule for months or even years once they get used to it.
How to do it
Make sure to eat nutrient-dense foods in your one meal to stay full until it’s time to eat again. We also recommend alternating your OMAD days with days in which you eat 2-3 meals to get adequate nutrition. To do OMAD long-term, it’s best to work with a physician and a dietitian or a nutritionist to make sure you are getting all the nutrients your body needs in your one meal.
Intermittent fasting schedules: OMAD
A typical OMAD schedule would involve eating between 5 pm and 6 pm, for example, and fasting the rest of the time.
Health benefits of OMAD
Compared to eating 3 times a day, eating only one meal within a 4-hour period has been shown to lead to weight loss and loss of fat mass. Those who eat 3 times a day typically have a higher BMI compared to those who eat only once. A small study showed that eating only dinner eliminated the need for insulin in type-2 diabetes patients. This fasting approach also resulted in improved HbA1C, lower body mass index, and reduced waist circumference.
Who is OMAD for?
Those most likely to benefit from OMAD are people looking to lose serious amounts of weight, reverse type 2 diabetes and lower their risk for Alzheimer’s and Parkinson’s by activating autophagy. If you are considering OMAD It’s best to start with shorter fasts of 14-18 hours, and work your way up over several days or weeks.
Alternate-day Fasting (ADF)
What is it?
Alternate-day fasting is the most studied method of intermittent fasting in humans. ADF involves alternating between days in which you consume no calories and days in which you eat normally.
Intermittent fasting schedules: Alternate-day fasting
Another way of looking at ADF is as three 36-hour fasts per week. Here’s an example schedule – eat normally on Monday until 6pm. Don’t eat at all until breakfast on Wednesday morning. Finish dinner by around 6pm Wednesday night. Now don’t eat again until breakfast on Friday. Eat normally the rest of the day and finish dinner by 6pm or so Friday night. Now don’t eat again until breakfast on Sunday.
With this intermittent fasting plan, you may allow yourself up to 500 or so calories on “fast” days, though many people prefer to not consume any calories. If you take the former approach, it’s important to get most of those calories from good fats like olive oil and to avoid carbohydrates. Carbs will kick you out of ketosis (fat-burning) and diminish the benefits of ADF. One example of a low-carb “meal” that is below 500 calories is some leafy greens with a tablespoon of olive oil and a handful of almonds.
What are the health benefits?
Weight loss
ADF and the 5:2 diet lead to 4–8% weight loss over 8–12 weeks in men and women with obesity.
ADF is an effective intermittent fasting method for weight loss especially when combined with a low-carb diet. ADF seems to cause similar weight loss compared to daily caloric restriction, although ADF may lead to greater reductions in fasting insulin and insulin resistance.
Other benefits
ADF increases life span in rodents by 80%, possibly by decreasing glucose levels and regulating insulin. It also reduces the incidence of cancer in lab animals genetically predisposed to it. Alternate day fasting may be better at improving insulin sensitivity and fasting insulin in humans compared to caloric restriction.
Who is ADF for?
People looking to jumpstart serious weight loss or reduce risk of disease. ADF is great for the first several months of a serious weight loss plan. Some people are able to maintain it long-term, but many fall back to one of the other schedules after they’ve lost most of the weight.
The 5:2 diet
What is it?
This intermittent fasting plan involves eating normally for five days each week and then fasting for the last two.
Intermittent fasting schedules: The 5:2 diet
For example, you might decide to fast Monday and Tuesday and then eat normally the rest of the week (or pick any other days that are convenient). You can also look at it as one 60-hour fast per week. Finish dinner at 6pm on Sunday night and don’t eat again until breakfast on Wednesday morning, for example.
Health benefits of the 5:2 diet
Weight loss
ADF and the 5:2 diet lead to 4–8% weight loss over 8–12 weeks in men and women with obesity.
Other benefits
The 5:2 diet can reduce markers of inflammation as well as lower total and LDL cholesterol, triglycerides, blood pressure, fasting insulin and insulin resistance.
Who is 5:2 for ?
People looking to lose significant weight. The 5:2 diet could also be of interest to people suffering from auto-immune disorders since a weekly 60-hour fasting period is long enough to kill off and allow replenishing of large numbers of old white (immune) cells.
Extended fasting
What is it?
This method involves going with no calories for 3-5 days. These types of fasts are usually done under medical supervision. All studies of prolonged fasting allow up to 500 calories during fasting days. These calories should come from low-protein, low-carb foods. This usually means vegetable juices and vegetable soup, averaging a total calorie intake of 200–250 kcal and 25–35 g of carbohydrates per day.
Health benefits of extended fasting
Modified extended fasting (up to 500 calories per day) has been shown to reduce body weight, reduce circulating blood glucose and blood lipids, improve emotional and physical well-being, reduce chronic pain, increase healthy gut microbes and reduce blood pressure.
Studies of water-only extended fasting are limited. Extended water-only fasting (5+ days) has been shown to reduce body weight and oxidative stress, improve blood pressure, improve lower tract urinary function, and improve quality of life during chemotherapy.
Who is extended fasting for?
Those who have significant weight to lose, as well as those who want to overcome stagnant weight loss, help their cells clean up themselves through autophagy, rejuvenate their immune system and fight risk factors for cancer and neurodegenerative diseases.
The bottom line
There are many intermittent fasting plans you can experiment with. We highly recommend you start with the 12/12 plan. It’s a great way just to consistently cut out those late-night snacks that really pack on the pounds. The 12/12 plan is really the essence of intermittent fasting – learning that you’re not going to die if you don’t eat for a few hours. Once you’ve mastered the 12/12 plan, add hours gradually over several days or weeks if you want to fast longer.
Of course, there are countless variations on the basic intermittent fasting plans we’ve outlined here. Some people practice 16:8 every day but relax a bit over the weekend. Others supplement a time-restricted eating plan like 14:10 with one 24-hour fast each week. Others practice time-restricted eating plan daily and throw in an occasional extended fast.
Remember that intermittent fasting isn’t a diet. It’s best to think of it as a healthy life-long habit like exercise and getting adequate nutrition. Don’t give up if you have a bad week. Start off slowly and build up over time. Slow and steady wins the race!
References:
What Fasting Style is Right For You?
