Intermittent Fasting has been gaining a ton of popularity recently, and thousands of people online are praising it for its simplicity and effectiveness. But just like with any diet, you need to understand the intermittent fasting pros and cons before you make a decision to stick to it.
While IF might seem like simple enough, and it really is, it still has its drawbacks and it doesn’t work for everyone. This is why we need to really dig deep into the pros and cons of fasting and the different methods of intermittent fasting.
Without further ado, let’s go.
What is Intermittent Fasting?
Intermittent Fasting – often referred to as simply “IF” – is a simple eating pattern that cycles between periods of fasting and eating. IF is more of a lifestyle than it is a diet because it doesn’t specify which foods you should eat but instead limits the time window you can eat in.
The main idea behind IF is to limit the time in which you can eat in throughout the day which should consequently should reduce the amount of calories you eat and give your body a chance to dip into its fats to burn for energy.
The most common intermittent fasting method is called the 16:8 IF. In the 16:8 you can eat for 8 hours and fast for the remaining 16.
The diet doesn’t specify when you can eat, and you can choose the hours you want to eat in and the hours to fast, but it does emphasize healthy eating during your fasting hours and doing physical activities.
Another popular Intermittent fasting method involves fasting for 24 hours twice every week.
Even though fasting has been practiced by humans since before history began (remember, ancient humans didn’t have food available all the time), it’s only recently that research started showing us the benefits of fasting and more people started intentionally doing it.
It’s kind of ironic how the abundance of food is causing us health issues that can only be solved by us fighting our urges to stay away from food and reduce our consumption.
Intermittent fasting has been gaining incredible popularity in the health and fitness community, and has become a go-to for thousands that are looking to lose weight and burn body fat.
Before you jump ahead to intermittent fasting, you should spend a few minutes discovering the health benefits of intermittent fasting you can expect and the negative affects of fasting you should be aware of.
If you do want to start right away, check out our Intermittent Fasting Ultimate Guide here.
Intermittent Fasting Pros and Cons
Here is a quick break down of the pros and cons of intermittent fasting:
|– Easy to Follow|
– Effective for Weight Loss
– No Calorie Counting Needed
– No Macro nutrient Calculations
– Unrestricted Eating Patterns
– Helps with Glucose Control
– Other Health Benefits
|– May Reduce Physical Activities|
– Hunger Pangs
– Fasting Headaches
– Can Promote Overeating
– Does Not Encourage Nutritious Eating
– Concerns for Certain Groups
– Untested Long-Term Side Effects
Its important to understand that fasting is not new. It’s something that humans have done for thousands of years, and it’s actually much more common than you think. For example, in almost every religion, there is some sort of fasting.
For example, Muslims fast the whole of the Holy Month of Ramada from sunrise to sunset and Jews fast on days of penitence and mourning. This means that billions of people around the world already practice fasting on a regular basis.
The good thing is that Intermittent fasting is easier than the religious fasting in a lot of ways, such as you can control the duration and you can still drink water during it. I’ll discuss this much further in the cons section, but for now, let’s start with the pros of intermittent fasting.
Intermittent Fasting Pros and Cons:
Intermittent Fasting Pros
Let’s discuss why would you willingly decide to stop eating for most of the day or even for two days completely every week. After all, food is delicious and it’s necessary for survival and sustenance. We can’t perform at our peak without food, right? Right?
Easy to Follow
The hardest thing about any diet is following it for a long time. This is the number one reason people fail to lose weight on a diet; it’s hard to stick to a strict diet for a long time.
To be honest, though, some diets are indeed hard to follow for a long time. Here are some of the reasons that make diets hard to follow:
- Difficult to understand/requires a lot of memorization.
- Difficult Calorie restrictions
- Very limited eating time windows
- Allows only certain combinations of foods together
- Eliminates certain food groups completely
- Difficult and/or time-consuming meal-prepping
- Cost (in supplements, pills, etc)
- Difficult adjusting periods and symptoms
For those of us who have tried out different diets over the years, we have all been through some if not all of these, and we know how difficult they can make a diet.
Thankfully, intermittent fasting has none of these to hold you back as we’ll see later in much more detail. But people who follow the Intermittent can tell you that you only really have some issues in the first couple of days.
I personally found it surprisingly easy to start intermittent fasting and before I knew it I went from the 16:8 system to an 18:6 without really struggling much.
If you already fast for religious reasons, you will find IF actually easier on your body and you will get used to it more quickly than someone who isn’t used to fasting at all. Even still, anyone can quickly be used to IF and follow it in the long term without any real struggles.
Effective for Weight Loss
The number one reason why people diet is to lose weight and Intermittent fasting do not disappoint in this regard. A 2018 study found that subjects who followed IF showed a significant decrease in their weight and fat mass.
And in a larger study that covered 11 trials which lasted between 8-24 weeks, authors concluded that Intermittent fasting was indeed able to achieve good results regarding both weight loss and metabolic improvements, and they indicated that longer-term trials were still needed to draw definitive conclusions.
Another study suggested that Intermittent fasting was found to be more effective in younger men (in their 20s) than it was in older men (in their 50s), however it was also found that muscle power stayed the same in both groups.
No Calorie Counting Needed
Calorie counting seems like a great idea to have control over your weight loss journey, but it really isn’t. Counting calories in all meals and having to constantly calculate how much calories you need and trying to continuously adjust your meal plans to fit in with the calorie restriction is just a headache.
Even if you use the best, easiest-to-use, most user-friendly app out there to do it, it is still a headache to measure portion sizes and tabulate your daily counts.
At first, I thought this was just me, but no, it’s not. According to a 2011 study, people are more likely to follow their plans when all pre-measured calorie-controlled foods are provided. The easy explanation is that people are more likely to follow something when it’s made easier to follow.
There are some services and commercial diets that provide such things for a fee, but this is when we hit another point; expense. Not that many people have the resources to pay for such programs over a long term, and even some that have resources will want to put that money to a better use.
This is why I really don’t follow Instagram fitness models that boast about their meals, calorie counts, and how they are creating calorie deficits every day. It’s just not sustainable for the average person.
Intermittent Fasting aims to create the same calorie deficit by encouraging you to eat the same as you normally would but eliminates a meal (or more) by restricting your eating time windows.
If you’re looking for another diet with no calorie-counting, check out our paleo-diet quick start guide.
No Macronutrient Calculations
The one thing that’s worse than calorie counting is macronutrient calculations and limitations. It’s just unreasonable to think that a person can calculate exactly how many carbs, proteins, and fats are in each meal to satisfy their needs and still lose weight.
Some popular diets require you to do exactly this. They require a significant restriction in your consumption of specific macronutrients, and while this can be done in a general-direction-kind-of-way, it’s incredibly hard to do with the precision some fitness gurus and movie stars claim to do.
Lowering your intake of certain macronutrients or completely eliminating certain food also requires you to replace some of your favorite foods with unfamiliar (and often hard-to-get and expensive) foods.
These need foods will also mean you will need to require new cooking skills and learn new recipes, and of course, you will need to do some shopping to update your kitchen accordingly.
All of this can easily overwhelm you and make you quickly give up on a diet, but Intermittent Fasting needs none of this. You can learn about it, decide to follow it, and start the very same day. Nothing beats simplicity.
Why do we have to choose between the foods we love the most and our health and fitness? Why can’t we be healthy and fit while still enjoying the occasional pizza or cheesecake?
According to a 2017 study, the crave for our favorite foods and the drive to eat them is one of the major contributors to failing in losing weight on a diet.
This is not a problem you should be worried about with intermittent fasting. You can still eat pretty much whatever you want in your non-fasting hours or days, but it’s still recommended to eat as healthily as possible.
Helps with Glucose Control
In 2018, researchers proposed that Intermittent fasting may help people with type 2 diabetes manage their blood sugar through weight loss in overweight or obese individuals, but it may worsen insulin sensitivity in healthy individuals.
A case series in 2019 showed how effective IF could be (with medical supervisions and a 6-hr long nutritional training) in reversing insulin resistance while maintaining control of blood sugars over a period of 7 months.
In all three cases, patients were able to stop insulin therapy, lose weight, improve their blood glucose overall, and even reduce their waist circumference.
Another 2019 study showed that intermittent energy restriction (such as with an intermittent restriction diet like the intermittent fasting diet) can be superior to continuous energy restriction (such as when you lower your calorie intake but still eat all day long), and the study concluded with the confirmation that studies with larger sample sizes are needed to confirm this.
If you’re looking for something that’s more specific to diabetics, you can check this type 1 diabetes diet for something a little more focused on diabetes.
Other Health Benefits
In other studies on Intermittent fasting, scientists found associations between IF and plenty of other health benefits. A study in 2018 on Ramadan fasting, for example, found that the fasting done during the month was able to lead to the reduction of total cholesterol (LDL) which participants also saw an increase in the levels of HDL.
Another study in 2014 found that IF was effective in combating systemic low-grade inflammation as well as some age-related chronic diseases that are linked to immune function without hindering or compromising a person’s physical performance.
Do you want to take your cholesterol problem more seriously? Check out our complete guide for a low-cholesterol diet.
Intermittent Fasting Pros and Cons:
Intermittent Fasting Cons
There have been many studies that investigates the fasting effects on body and mind, and they are definitely worth considering before jumping into the diet.
Headaches, fatigue, dehydration, and a diminished sleep quality can be some of the dangers of intermittent fasting.
But it’s worth noting here that you are definitely not going to experience all of the possible intermittent fasting side effects at once, and some people, like me, do not experience any side effects of fasting at all.
May Reduce Physical Activities
This is one of the more common symptoms people experience when they start experimenting with intermittent fasting, but it actually should not be counted as one of the disadvantages of intermittent fasting, let me tell you why.
When most people start their IF routines, they, sometimes subconsciously, believe that they should be (or need to be) less active during their fasting hours. This is actually not true, and research has shown how exercise while fasting can have greater results.
When people start reducing their physical activities and changing their exercise routines during their fasting hours, it’s normal to feel fatigue, but it is not actually a side effect of IF.
However, if you do feel unnaturally tired when you start IF without changing your routines, it’s a good idea to talk to your doctor as it may be caused by a serious cause.
Gnawing, painful feelings in your stomach or the left side of your abdomen are what is often referred to as Hunger Pangs. Hunger Pangs happen when your stomach is empty, and they are one of more common side effects of fasting.
However, hunger pangs are not new, and they are less common with intermittent fasting than they are in dry fasting (dry fasting is when you restrict both food and liquid). Even dry fasting science has shown that hunger pangs can be avoided if you take simple steps to avoid them, and these become much easier on IF.
For example, one of the most common IF mistakes which lead to hunger pangs is not drinking enough water. Another mistake that causes it is binge eating during your not fasting hours.
If you stay hydrated and eat healthily, hunger pangs are unlikely to become a problem.
Intermittent fasting does not cause headaches directly, but it can lead to it through something else. An intermittent fasting headache can indeed be annoying since you can’t just reach for a pill to make it go away (because this will break your fast).
For example, your blood sugar may get low when you fast periodically and consume lower calories, and these fluctuations in blood sugar can cause headaches as your body starts shifting stress adaptive hormones such as cortisol.
Another cause could be dehydration, and both can be solved easily by eating healthily and drinking more frequently.
Can Promote Overeating
Some no-fasting periods in some IF protocols are labelled as “feasting” periods, which can lead people to indeed “feast” in the most extreme way they can.
These feasting periods indeed have no restrictions on meal frequency, food types. or meal size, but this can actually lead to overeating.
Some people also feel like they’ve “earned” the right to eat whatever they want after a difficult week or even a day of fasting. This is wrong, you should fight these urges and eat moderately, even when feasting.
Does Not Encourage Nutritious Eating
Since Intermittent fasting has no restrictions regarding what you can eat, some people take this as the greenlight to eat whatever they want during their fasting days.
This is a really bad idea; Intermittent fasting is not magical, and you can still gain weight if you overeat and consume more calories than you can burn.
Intermittent fasting can encourage your body to burn fat, but it can’t magically burn everything you eat. The common advice, and the correct one, is to eat as if you usually do during your feeding windows and not try to compensate your fasting in any way.
Concerns for Certain Groups
As you will see later, intermittent fasting is not for everyone. Some people have pre-existing medical conditions that should prevent them from following an Intermittent fasting protocol.
For example, someone with an eating disorder should not try Intermittent fasting as it can make their condition worse.
People who also need to take medications at certain times can’t do IF unless they can get an approval from their doctor and can find a way to make their IF align with the medications schedules.
Untested Long-Term Side Effects
While fasting is not new, and even intermittent fasting is not new by anyway, much of the research that studied the pros and cons of it is still relatively new. There is much more research needed into the pros and cons of intermittent fasting 16/8 and alternate day fasting protocols.
More studies into the long-term effects of Intermittent fasting are needed to determine whether this eating pattern can have certain effects on your body in a few years and a few decades in the future.
For now, if you want to stay safe, you should consult with your health provider before starting and IF program.
How to lose weight with Intermittent Fasting?
Now that you know everything you need to know about intermittent fasting pros and cons, let’s take a minute to discuss the main advantage you probably want from Intermittent fasting; losing weight.
As discussed earlier, Intermittent fasting can be a great tool for weight loss, and this weight loss can be accelerated if you combine Intermittent fasting with regular exercise and healthy eating.
Even a 30-minutes daily walk can be hugely beneficial for you, especially if you are living the desk life and don’t get much exercise during the day.
Intermittent Fasting Pros and Cons:
Intermittent Fasting Methods
There are many methods to do intermittent fasting, but these three are the most common:
- 16/8 Method: In this method, you skip either breakfast or dinner – whichever is more convenient and easier to stick to. You can eat normally during your 8-hour feeding window every day and you fast during the remaining 16.
- The 5:2 Method: You can eat normally for five days of the week, but then for two days you should limit your calorie intake to only 500-600 days calories.
- Eat-Stop-Eat: You can eat normally normally during the week, but for one (or two if you can), you should not eat anything for 24 hours. This means you can’t eat anything from a dinner one day to the dinner of the next day.
The most important thing to remember is that you shouldn’t try to compensate by overeating during your non fasting periods. During your non fasting periods, you should just stick to a healthy eating plan as if you would have without intermittent fasting.
If you do this, you should be able to easily reduce your calorie intake and lose weight and belly fat more easily.
The effect on your cells and hormones
Have you ever thought why our bodies store fats in the first place? This is an evolutionary advantage that our bodies have developed to ensure we can have energy even when we don’t get have access to foods, and it’s a very useful one.
This meant that, for our ancestors, they can stay alive and still have energy for hunting and gathering even when they have not eaten anything for a while, which gave us better survival chances.
But because we always have access to food nowadays, our bodies very rarely tap into their energy storage, because why do so when they can so easily burn glucose that we give it regularly, and give it too much of it at that.
By understanding this, we can understand why intermittent fasting is actually quite useful for weight loss. When you fast and stop eating, your body will start changing things around to make the stored energy accessible to actually use it.
These changes happen in your nervous system and hormones, here are a few of them:
- Human Growth Hormone (HGH): HGH is very important for us, and when we fast, we can see it skyrocket by as much as 5-fold the normal levels. Growth hormone is essential for burning fat and gaining muscle.
- Insulin: Insulin increases every time we eat, and it takes a while to get back to a lower level. When we fast, however, Insulin decreases dramatically, and this facilitates fat burning.
- Norepinephrine (noradrenaline): The nervous system uses Norepinephrine to break down body fat into free fatty acids that can be burned for energy, and fasting increases it.
Studies have also found that fasting for 48 hours was enough to boost metabolism by 3.6-14%, but longer fasting periods are not recommended as they can indeed suppress metabolism. This means that, despite what the 6-meal-followers may tell you, short-term fasting can increase fat burning and boost your metabolism.
A boosted metabolism combined with healthy eating, regular exercise, and less calorie intake (by eliminating one meal) is a wonderful recipe for healthy weight loss that you can follow for a long time without worrying about serious side effects.
Who Should Not Do Intermittent Fasting?
Generally speaking, intermittent fasting is not recommended for people with hypertension, high levels of LDL cholesterol, cardiovascular disease (heart disease), liver and kidney diseases, hyperglycemia, and abnormally high levels of uric acid in the blood.
Intermittent fasting is not recommended for people who have always struggled with eating disorders. It’s also not recommending for women who are pregnant or breastfeeding.
People with these conditions can experience some of the more serious side effects of Intermittent fasting and should not start a diet in general without consulting their doctor first.
People with chronic health issues should always consult their doctor for the best nutritional plans available to them. The advice of a website, a mobile application, or an influencer should never replace or come before the advice of your doctor.
Intermittent Fasting Pros and Cons
Is fasting safe?
Yes, fasting is safe. Billions of people around the world fast for spiritual, religious, and health reasons and lead perfectly normal lives. Recent research has found plenty of health benefits associated with fasting and didn’t find any huge problems that it may cause.
However, fasting is not for everyone, and some people with certain medical conditions should not try fasting. In general, short-term fasting should be fine as long as you eat healthily in your non fasting periods and stay active and hydrate when possible.
Is Intermittent fasting bad for blood pressure?
Intermittent fasting can lower your diastolic blood pressure and prevent hypertension by increasing the BDNF factor and activating the parasympathetic system.
In general, fasting can make your blood pressure get lower, and for short-term fasting such as with IF, this should not cause any issues. However, if this results in an electrolyte imbalance, it can make your heart more prone to problems in the rate of the heartbeat.
Can Intermittent fasting cause hair loss?
Intermittent fasting is designed around creating a calorie deficit which is how we lose weight. Some people can experience some side effects of weight loss such as hair loss, irregular periods, and lower blood pressure.
Short periods of intermittent fasting do not cause the significant amount of calorie deficit needed for hair loss to become a primary concern, but if you are concerned, you should consult with your health provider before starting on an Intermittent Fasting protocol.
How long to get used to intermittent fasting?
Some people can get used to intermittent fasting in just a few days if they already practice fasting for spiritual or religious reasons in other times of the years, while it can take others a few weeks to get really adjusted to their new routine.
For most people, it should be easy and you should expect all the side effects to subside within a month at max from the start of your fasting.
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Gasmi M, Sellami M, Denham J, et al. Time-restricted feeding influences immune responses without compromising muscle performance in older men. Nutrition. 2018;51-52:29-37. doi:10.1016/j.nut.2017.12.014
Carter S, Clifton PM, Keogh JB. The effect of intermittent compared with continuous energy restriction on glycaemic control in patients with type 2 diabetes: 24-month follow-up of a randomised noninferiority trial. Diabetes Res Clin Pract. 2019;151:11-19. doi:10.1016/j.diabres.2019.03.022
Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. K Y Ho, J D Veldhuis, M L Johnson, R Furlanetto, W S Evans, K G Alberti, and M O Thorner