Back in April 2014, when I wrote my first intermittent fasting article, I was accused of encouraging people to starve themselves. I still remember how a particular weight loss coach carried the matter to her BB group, and I was the topic of their discussion.
Since the time I published that article, there have been new studies on fasting as a modality for weight loss, longevity, disease prevention, and as part of treatment for chronic diseases.
This post is the third update of my intermittent fasting article. I have made significant changes to the original post to reflect current scientific research on intermittent fasting/time-restricted feeding.
Please note that this post is about intermittent fasting only. It doesn’t apply to prolonged fasting (a prolonged fast is any fast that lasts for 48 hours or more).
Enjoy the article.
What I Used to Believe About Intermittent Fasting
When I first became a fitness professional, I used to believe that breakfast is the most important meal of the day. Like many other well-meaning fitness pros, I preached the message of “eat breakfast like a king, lunch like a prince and dinner like a pauper.” It was the dietary philosophy I lived and preached.
Then I began to read about intermittent fasting and all its health benefits, and I became a proponent.
Isn’t Intermittent Fasting Another Fad Diet?
No, intermittent fasting is not a fad diet. Intermittent fasting became popular in 2013 when Hollywood celebrities like Hugh Jackman began to use the 16:8 protocol to get ripped for movie roles. However, intermittent fasting didn’t originate in Hollywood. Scientists have been studying the various forms of fasting in animals and humans before it became mainstream.
Up until 2017, I used to believe intermittent fasting is all about skipping breakfast, and I was always looking for studies that support my view. Yes, we all suffer from confirmation bias.
My view drastically changed when I began to learn more about circadian biology and how it affects everything. Now I know how metabolically beneficial compressing one’s food intake to certain hours within the human biological day can be.
What Is Intermittent Fasting?
Intermittent fasting is a method of eating that cycles between periods of fasting and feeding known as fasting window and feeding window, respectively.
When many people think about intermittent fasting, they think about skipping breakfast.
Intermittent fasting is not about skipping meals; it is about compressing your eating to a particular time window during the day (the human biological day when the sun is out).
There are advanced protocols of intermittent fasting that require skipping one or two meals or skipping a whole day meal (OMAD, alternate-day fasting, and the 5:2 diet ). However, in its simplest form, intermittent fasting is about eating all your meals within a specific time window each day. Scientists call it time-restricted feeding (TRF).
All intermittent fasting protocols are a form of time-restricted feeding.
Intermittent fasting is a method of eating that cycles between periods of fasting and feeding known as fasting window and feeding window, respectively. Intermittent fasting is not about skipping meals; it is about compressing your eating to a particular time window during the day
Time-Restricted Feeding Explained
As explained earlier, time-restricted feeding (TRF) means that you eat all of your meals and within a particular window of time during the day (human biological day). There are two components of time-restricted feeding.
The two components of time-restricted feeding:
1. The circadian rhythm component
2. The intermittent fasting component
The Circadian Rythm Component
Humans are diurnal. We’re biologically wired to eat during the day and fast during night time. When we don’t eat in alignment with our circadian rhythms, it can lead to metabolic disruptions that can make us susceptible to weight gain and a host of other chronic health conditions. When it comes to aligning your eating with your circadian rhythm, regularity is crucial.
- You can’t eat within an 8-hour window today and eat within a 14-hour window tomorrow.
- Your first and last meals must be on regular schedules.
- You can’t eat breakfast at 8 am one day, and 11 am on another day, and you can’t have dinner at 6 pm one night and 9 pm on another night.
The Intermittent Fasting Component
As I said before, Intermittent fasting is not about skipping meals. It is about compressing your eating to a particular time window.
Therefore, if you’re eating your daily meals between 9 am-6 pm or 10 am-7 pm — and you don’t take any calorie-containing food/beverage before your first meal and after your last meal — you’re already doing intermittent fasting. Congratulations!
Types of Intermittent Fasting
The 16:8 Protocol: In this method, you’ll fast for 16 hours and eat all your meals for the day within an 8-hour window. Your fasting window includes your sleeping hours.
The 18:6 Protocol: In this method, you’ll fast for 18 hours and eat all your meals for the day within an 8-hour window. Your fasting window includes your sleeping hours.
The One Meal A Day Diet (OMAD) Protocol: The OMAD diet is an advanced intermittent fasting protocol. You fast for 23 hours and eat all of your daily calories in just one meal each day (23:1).
The 5:2 Protocol: In this form of intermittent fasting, you will eat normally for five days a week and drastically limit caloric intake to 25% two days a week. The calorie restriction days can be two consecutive days, or non-consecutive.
The Alternate-day Fasting Protocol: In this method, you fast one day by not eating at all or eating 500 calories or fewer and eat normally the next day. You’re alternating between one day of fast and one day of normal feeding.
The 16:8 and 18:6 methods are the easiest form of intermittent fasting.The alternate-day fast is the most scientifically researched intermittent fasting protocol.
Why Timing Matters
When intermittent fasting first became mainstream around 2012, many people (including yours truly) think it’s about skipping breakfast. Even today, some people still think intermittent fasting means skipping breakfast.
Intermittent fasting isn’t about skipping breakfast. It is about compressing your eating to a particular time window during the day.
In the first and second edition of this article, I argued that breakfast is not the meal one eats in the morning. My position on that is still the same because, by definition, breakfast means breaking the fast. It means your first meal of the day, not the meal you eat in the morning.
Every morning you wake up in a fasted state. How many hours you’ve fasted depend on when you had your last meal the previous day, and how many hours of sleep you had. You break your fast with the first meal you eat after those long hours of fasting. Breakfast, therefore, is your first meal of the day.
The question then is, is it okay to extend the fast till afternoon? In other words, is it okay to skip breakfast? Please grab a cup of green tea and let’s turn to health scientists for the answer.
To Skip Breakfast or Not
Whether you’re doing intermittent fasting or not, when you eat has a tremendous impact on your cardiometabolic health than you can ever imagine. Studies have shown that eating late at night is detrimental to the body. Late-night eating is defined as consuming any calorie-containing food or drink after 8 pm.
Therefore, if skipping one or two meals is the goal, it’s best to skip dinner instead of breakfast.
Intermittent fasting isn’t about skipping breakfast; it is about compressing your eating to a particular time window. That means you can still eat three meals a day as long as you’re eating within your feeding window. However, you can do an advanced protocol of intermittent fasting, where you skip one or two meals a day. Or where you don’t eat at all during a 24 hr period.
Late-night Eating Is Not Good For Your Waistlines
In this study, researchers found a strong association between nighttime eating and increased body fat.
According to the study, “these results provide evidence that the consumption of food during the circadian evening and/or night, independent of more traditional risk factors such as amount or content of food intake and activity level, plays an important role in body composition.” (Emphasis mine)
A 2013 study of 420 people who followed a 30-week weight loss programme found that the timing of food intake predicts weight loss effectiveness.
“Eating late may influence the success of weight-loss therapy. Novel therapeutic strategies should incorporate not only the caloric intake and macronutrient distribution—as is classically done—but also the timing of food.” (Emphasis mine)
Late-night Eating Is Not Good For Your Health
In a crossover study, early time-restricted feeding was shown to improve insulin sensitivity, blood pressure, and oxidative stress in prediabetic men.
The cardiometabolic improvements seen in this study were independent of weight loss.
A 2017 study published in the journal of current biology found meal timing to be a major regulator of the human circadian system. According to study authours, “timed meals play a role in synchronising peripheral circadian rhythms in humans.”
Time-restricted feeding is a preventative and therapeutic intervention against diverse nutritional challenges. This study here
and this one here support the findings in the other studies referenced above.
There is strong evidence to support the notion that late-night eating is detrimental to our health and waistlines. Whenever you’re doing an advanced intermittent fasting protocol, skip dinner, not breakfast.
Can Intermittent Fasting Help Me Lose Weight?
You may be saying, “Esta, this your long story no concern me o. My question is, will I lose weight with this time-restricted feeding/intermittent fasting thing?”
The answer is both Yes and No.
You will lose weight with intermittent fasting as long as you’re not eating three days worth of meal within your daily 6-8hours feeding window.
Some people use intermittent fasting as a crutch for bad eating. If weight loss is the goal, what you eat, and how much you eat during your feeding window matter.
A 2018 study conducted at the University of Illinois looked at the effects of TRF on weight loss.
Twenty-three obese and sedentary subjects participated in an 8-h time-restricted feeding intervention. The participants were allowed to eat whatever they wanted between 10 am to 6 pm and fasted between 6 pm to 10 am (water only fasting). The study lasted for 12 weeks.
At the end of the 12 weeks study, the average weight loss was approximately 3% of the starting weight. That means a participant who started at 100kg lost around 3kg at the end of the 12 weeks study.
You might be scratching your head at the 3kg loss in 12kg. Like, “what, 3kg in 12 weeks?. That’s way too small.”
I feel you, but let me explain the reason the average weight loss was 3%.
The objective of the study was to see whether people can lose weight by just compressing their food intake to a particular window during the day. That’s why the feeding was ad libitum; study participants ate as they desired. They didn’t count calories, didn’t change anything in their diet, and they didn’t change their activity level. The only thing they did was to compress their feeding window.
On average, the participants ate 300 fewer calories per day throughout the 12 weeks study. So without effort, the average participant lost 3% of their body weight in 12 weeks just by eating within an eight-hour window.
Key lesson from the study
Intermittent fasting, or any nutrition protocol for that matter, is not a magic bullet for weight loss. Therefore, if your goal is to lose more than 3% of your body weight in three months, you might want to do a combination of the three things listed below.
1Eat quality foods in the right quantity (no overeating, no sugar, no junks, no highly processed foods.
2Eat within 6-8 hours window (16:8 or 18:6 protocols)
If can you combine these three things, you can expect to lose a significant amount in twelve weeks.
What Breaks A Fast?
One of the questions I get asked a lot is this, “what breaks a fast?” People ask this question because they want to know what they can drink or eat during the fasting window.
Well, the answer depends on why you’re fasting. I fast every day using the 18:6 protocol and the only thing I take during my fasting window is plain water.
The reason is that my goal is to align my eating with my circadian rhythms. For this purpose, I avoid anything that can kickstart the metabolic process in the liver.
If your goal is to align your eating with your circadian rhythms, you should stay away from everything except plain water or plain green tea. Not even coffee because it kickstarts the metabolic process in the liver.
When the liver starts working, the other organs of the digestives system get the signal that it’s day time. Just as the brain sees the light and wakes up, the liver sees food or any calorie-containing drink and wakes up.
If your goal is to eat in alignment with your circadian rhythms, please note that regularity is vital. Therefore, your eating pattern can’t be erratic. What that means is that your first and last meals/calorie-containing drinks must be on regular schedules.
If you eat breakfast at 9 am today, you can’t eat at 11 am or 1 pm tomorrow. Also, if you eat your last meal at 7 pm today, you can’t eat tomorrow’s own at 9 pm. The first rule here is regularity.
Can I Still Eat 3 Meals A Day?
Yes, you can still eat three meals a day while doing intermittent fasting. Remember, intermittent fasting isn’t primarily about skipping meals; it’s about compressing your eating to a particular time window during the day.
You don’t need to skip any meals, especially if your goal is to make this way of eating a lifestyle.
What About the OMAD?
The one meal a day diet (OMAD) is an advanced intermittent fasting protocol. You fast for 23 hours and eat one meal a day within one hour window.
Is The OMAD Diet Safe?
In the short-term, the answer is yes. No one is going to die for not eating for 23 hours. Also, fasting has been shown to have numerous health benefits. So, ignore the people who are saying you need to eat 5-6 meals a day to raise your metabolism. Eating round the clock is detrimental to your metabolism!
That being said, be aware that following a fasting protocol that limits your feeding to a very short window isn’t something you should do for more than 8-12 weeks. The studies I have seen suggest that the One Meal A Day protocol may increase some cardiovascular disease risk factors. For this sole reason, you should not do the diet for more than 8-12 weeks at a stretch.
There you have it! I hope you enjoyed reading this post as much as I enjoyed writing it.
Now I want to hear from you! Tell me in the comments what you learned from this article. Also, if you have any questions, drop them in the comments, and I’ll answer them.