Two years ago, I wrote this article on intermittent fasting (IF). Since then, I have learned a lot more about IF – the purpose of IF and its benefits. So, I want to re-answer the question, does intermittent fasting work, and show how I’ve changed my mind.
To distinguish between what I wrote two years ago and what I’ve added recently, what I’ve added recently will look just like this (black font, no background). What I wrote two years ago will be included in a taupe-colored text box like this…
Like This…
Let’s start with how many meals we should be eating in a day…
Do You Need to Eat Three Times a Day?
In this section, I wrote about what led me to question how many meals we are supposed to eat in a day. I think it’s important to explain why I wrote about IF two years ago. So, here’s why I started looking into IF in the first place:
During my time as a nutrition student, I was told that patients should eat three meals a day and snacks between. Now, several of the patients had diabetes. So, it was important for them to eat consistent meals because of their insulin schedule.
However, for the other patients, I think it was just easier to tell them to eat three meals a day. Plus, three meals a day is a big part of the culture in the West.
Once I was asked if intermittent fasting was good for our bodies, but I wanted to say no right away. I mean, eating three consistent meals every day was the best thing for our bodies, right? It was at that moment that I realized I was just repeating what I’d been told without testing it to be true first.
So, this leads me to ask… How many meals per day should you eat, and is it okay to skip meals for times of fasting?
How Many Meals A Day Do I Need?
Now, let’s look at the conclusion I came up with regarding how many meals we should have per day…
There’s not an easy answer to the question of how many meals you should eat per day.
When looking into the research side, the only answer I could find was quite vague. The suggestion was to eat when you’re hungry until you’re full, and then repeat once you get hungry again. For those of you who don’t really know when you’re hungry and when you’re full, three meals a day might be a good guideline for you.
One thing I like to recommend is to ask yourself why you’re eating. If you’re eating because your stomach is rumbling that’s great. If you’re eating for any other reason then you probably shouldn’t be eating. (Except for those occasional times you eat for fun.)
Too often you can eat for comfort instead of for hunger. And once you form the habit of comfort eating, you will not be able to tell when you’re truly hungry.
I still stand by the conclusion that we should only eat when we’re hungry. However, what I did not consider two years ago was how the body has been designed to work. Before we can figure out how many meals the body needs in a day, we need to look at how the body works.
How the Body Works
PAUSE: I dig deeper into how the body works via biological rhythms in this article. I recommend reading that one to better understand how the body is affected by your diet and lifestyle.
To sum up the article on the biological clock, the body works in rhythms throughout the day. These rhythms are centered around the position of the sun in the sky. As the sun comes up in the morning, the body knows to decrease melatonin to switch from resting to working. Throughout the day, the body releases hormones, digestive enzymes, and completes other tasks according to the biological rhythms that are nearly in every organ and tissue in the body. Each biological rhythm is kept in sync by the body’s master clock, which is largely regulated by the position of the sun in the sky.
Taking this into account, there is some research to suggest that the body is better able to digest food during daylight hours. If this is true, then it is most likely because the increase in melatonin as the sun goes down causes the body to shift into rest mode. During rest mode, the body has certain tasks it needs to complete. However, eating during this time takes away energy the body needs to complete other tasks. This disruption in biological rhythms might also be why we see higher levels of obesity in night shift workers.
If you chose to ignore my suggestion to read my article on biological rhythms, I really do recommend reading it. What I said here is a summary that does not cover important details.
What is Intermittent Fasting?
Here was my understanding of IF two years ago…
An absolute fast is when one avoids food and beverages, which is not advised for longer than three days. A normal fast is when one avoids food and beverages but can drink water, which is not recommended for longer than 40 days. A partial fast is more flexible in that one can either fast for a certain time during the day, or choose what foods to fast from for a time period.
You can break this down further into the trending fasts we have today. For example, the cleansing fast, Daniel fast, alternate day fast, 5:2 diet, 16/8 fast, or warrior fast.
Here is my understanding of IF today…
The goal with IF is to get the nutrients and calories you need in a shorter period of time. Instead of eating over 13+ hours in the day, you narrow that window down to at less than 12 hours.
IF can be done in different ways. Baseline is considered to be 12:12 (first number is hours fasting, second number is hours to eat all your meals within). Once you start IF, you could do a 13:11, 14:10, 15:9, 16:8, 17:7, or 18:6. Some even go up to 20:4.
How short your eating window is largely dependent on you. However, it is important to note that the most benefits of IF are seen with at least a 16:8. A 16:8 is actually the most popular application of IF.
Misconceptions of Intermittent Fasting
Unfortunately, there are a lot of misconceptions about intermittent fasting out there. So, I want to address two of the misconceptions before we get to the benefits of IF.
One main misconception (which I had believed two years ago) was that IF requires you to reduce the number of calories you get in a day. This is not (necessarily) true. As said above, the goal of IF is to meet all of your needs within a smaller eating window.
Another misconception is the confusion of intermittent fasting with extended fasting. Now I want to be clear, intermittent fasting is not extended fasting. Some who do IF may go up to 24-48 hours without food periodically, but this is not necessary to still reap benefits from IF. However, the longer you are able to fast, the more benefits you will see from IF. Extended fasts of 5 days actually have some major benefits that you don’t see with IF.
But, remember… The goal is to meet all of your body’s nutrient and calorie needs within your eating window, no matter how small it is.
You may be thinking now, why would someone want to skip meals? The benefits must be really good to get you to give up a meal.
Let’s go over a handful of the benefits of fasting…
Does Intermittent Fasting Work?
Two years ago, I would have answered this question with a “yes?” As you will see below, I didn’t quite understand how the body’s design fits into not only IF but extended fasting as well.
The motivation behind fasting is based on the belief of five main things… It helps with healing, rest for the body, ability to focus and be calm, breaking food addictions, and spiritual dependence.
Many of these believed benefits of fasting may be true; however, there have not been many studies done on humans to prove them. (Most of the studies were done on animals.) From the few studies that have been done, fasting was shown to promote weight loss and potentially improve blood sugar control. On the other hand, periods of fasting may result in over-eating once the fast is over, which would not help with weight loss.
At the end of the day, there needs to be more studies done to determine if fasting should be encouraged or not. From the few studies that are available, fasting does not appear to be harmful.
After what I’ve learned in the past year, my answer to this question is yes, to an extent.
I want to be clear – I do not believe IF will cure everything. There is some damage in the body that, unfortunately, may not ever be completely reversed. However, there are plenty of health issues that can be reduced through IF and extended fasting.
Benefits seen with fasting:
- Fat adaptation – the body is able to use fat to make energy (through the use of ketones) and better able to break down excessive fat on the body; using ketones for energy makes cleaner and more energy compared to glucose (or sugar)
- Autophagy – the body breaks down and recycles old and/or damaged cells
- Stem cell production – stimulates the production of stem cells (new, baby cells) to replace old and/or damaged cells
- Reduces inflammation – fasting helps regulate the immune system, including down-regulating the inflammasome (AKA inflammation pathways)
- Better mental capacity – hippocampus (the memory center) expands; may also have something to do with ketones making cleaner energy
- Balanced energy levels – fasting causes the release of norepinephrine, which is the hormone that helps you feel good; stimulates the release of the right hormones at the right time
There are several more benefits to fasting that I will have to cover in another article. I do want to note that these benefits are typically seen in studies done on extending fasting. However, studies done on IF suggest that these benefits are also seen with IF, but on a lesser level than an extended fast.
So, back to the question at hand: does intermittent fasting work?
- If you’re looking to eat in a way that syncs with your biological rhythms and how your body has been designed to work, then yes.
- If you’re looking to cure every ailment you have, then no. Or, if you refuse to clean up your diet then IF will not work.
IF and/or extended fasting will have to be paired with other interventions to heal the body. Since the body is so interconnected, your approach will have to be interconnected (AKA holistic).
If you want to learn more about this holistic approach, you can learn more here.
Is Intermittent Fasting for Me?
When I wrote this article, I was not aware of all of the studies that have been done on IF and its benefits. I also didn’t know about the body’s biological rhythms and how they are disrupted by erratic eating patterns. I also didn’t know that the Israelites from the Old Testament in the Bible most likely ate only two meals each day – one at mid-day and one before sundown.
Now that I’ve learned so much more about IF and extended fasting, I’ve changed my mind on what intermittent fasting does and who should do it. But, first, here’s my conclusion about doing IF from two years ago:
The better question to ask yourself is, “Why do I want to fast?” The only advice I can give is to not fast if you feel like you have to or think it will help you lose weight fast. If you do fast for those reasons, you devalue the original purpose of fasting – to not be a slave to the foods you eat. To be in control of what you eat.
So, for those of you who want to fast, I challenge you to fast to be in control of your diet. If the other consequences (weight loss, normal blood sugar levels) come with fasting, then enjoy the fruit of your labor.
In my experience, fasting can do some amazing things for you and your health, if done with the right intentions. Otherwise, I’m afraid that you will be sorely disappointed.
I still believe IF is a great practice to help you be in control of what you eat. However, IF has become a tool for much more than that.
What I Believe Today
After learning the benefits of and reasons to do IF, I’m convinced everyone should meet their nutrient and calorie needs within a 12-hour window. This goes for kids, adults, pregnant women, and the elderly. The only life stage that this is not beneficial for is infants who may need to eat every 3-4 hours.
The body needs at least 12 hours straight to complete all of its other non-food-related tasks.
For kids up to teens, it is essential that they are able to meet all of their nutrient needs since they are growing. So, if they can only do a 12:12, then that’s ok. If they can meet all of their nutrient needs doing a 14:10 or 16:8 without having any symptoms, then that’s good too. We just need to be careful with shorter eating windows for kids and teens because they need to have nutrients to grow and develop. (I recommend trying IF with kids or teens only under the supervision of a health professional who is experienced with IF.)
For adults, I believe there are many benefits to IF that help the body get and stay healthy. Since adults are no longer growing like when they were kids or teens, there is no longer a concern of stunting growth or development. However, if you aren’t use to fasting, then you may need to build up to going longer without food.
**If you’re taking prescription medications, you need to talk to your Doctor before fasting. This is especially true for those taking insulin. Your Doctor will need to change the dosage and/or timing of your medications.**
Where to Start with Intermittent Fasting?
If you’re not taking prescription medications, a good place to start is by cutting out snacks between meals. Once you’ve done that, you can alter the timing of dinner and breakfast to be 12 hours apart. For example, if you eat dinner at 6pm, then you wouldn’t eat until 6am the next day.
After you have gotten the 12-hour eating window down, you can start pushing breakfast 30 minutes to an hour later or eating dinner 30 minutes to an hour earlier. Keep pushing back breakfast or moving up breakfast earlier until you found an eating window that works for you.
If you need help implementing IF in a sustainable way, then you might benefit from working one-on-one with me. As a Licensed Dietitian, I’ve trained to be able to help people IF successfully. Plus, I have created a way you can spread out payments instead of having to pay $300-$1000 upfront for personalized help from a licensed health professional.
If you want to learn more about working with me, you can read more about the membership site I’m working on that will be only $5-$25 per month to join here.
I’m curious about what your experience is with intermittent fasting! Have you tried it? If so, which fast did you do and how did that work out for you? If you haven’t tried fasting yet but are considering it, which fast are you thinking about trying?
Let me know in the comments below!