- What is Intermittent Fasting?
- 7 Health Benefits of Intermittent Fasting
- The Most Popular Intermittent Fasting Schedules
- Fasting for Weight Management
- Intermittent Fasting and Keto
- Tips for Starting and Sticking With Intermittent Fasting
- What to Drink During Your Fasting Window
- Intermittent Fasting – Is it Safe for Women?
- Frequently Asked Fasting Questions
A diet that is super easy to follow and also has heaps of health benefits, way beyond weight loss. That’s pretty much the dream combination, right? Welcome to intermittent fasting! We’re here to break it all down for you, so you can even start today if you’d like!
Read on to learn about the many benefits of intermittent fasting, the different fasting schedules you can follow, the foods and drinks you can include during eating and fasting periods, and how to maximize the effects of intermittent fasting.
What is intermittent fasting?
Intermittent fasting is actually quite simple. It is basically a schedule that divides your day into two parts: an eating window and a fasting window. While most diet plans are fundamentally concerned with WHAT you eat, this plan is all about WHEN you eat, and that’s it.
There’s no meal planning, no shopping lists or other advance preparation. You can choose the ideal fasting schedule to fit your lifestyle, and then all you have to do is follow the schedule! The structure of intermittent fasting is meant to make the most of your body’s natural metabolic processes every day, so that you can be on your way to long term optimal health.
Is intermittent fasting good for you?
Intermittent fasting might be the simplest diet ever! And its potential health benefits are so vast and varied, it almost seems too good to be true! Whether you want to enhance athletic performance or energy, promote healthy weight management or support brain health, intermittent fasting may help. Here are the top 7 health benefits (with scientific evidence) of intermittent fasting:
1. May support healthy weight management
By training your body to burn fat for energy, intermittent fasting can tap into your body’s natural weight loss mechanisms. Plus, the simplicity of the plan means you’re much more likely to stick with it!
When you practice intermittent fasting and successfully switch your body into fat-burning mode, your body is actually accessing fat to burn. (1)
2. May boost your energy
Unlike so many calorie restriction diets that can make you feel sluggish, many people report that intermittent fasting helps them feel more energetic. No more afternoon slumps!
3. May promote mental clarity and focus
Intermittent fasting has the ability to boost your brainpower because it increases your BDNF, which supports brain connectivity and new neuron growth. The hormonal changes that occur when you follow intermittent fasting have actually been shown to support memory and brain function. (2)
4. May help maintain healthy blood sugar levels
Fasting can help support the maintenance of normal blood sugar levels. While you’re in your fasting window, no new glucose is being supplied to your body, which means your body has no choice but to use up stored glucose. (3)
5. May support heart health
Intermittent fasting is an excellent supporter of heart health because it is associated with supporting healthy cholesterol and triglyceride levels. (4)
6. May support the body’s anti-inflammatory response
Your body relies on a process called “autophagy” to clear out old and damaged tissues and cells. When you fast and give your body a break from the constant effort of digesting food, it seems to be able to focus more energy on normal repair efforts, which means supporting your body’s natural anti-inflammatory response. (5)
So you’ve decided to give intermittent fasting a try (congratulations!), and you need to know what the eating schedule is. Even just a quick online search probably gave you an overwhelming amount of information about the different kinds of plans, durations, days, eating patterns, etc…
With such a wide variety of intermittent fasting regimens, how can you figure out which one is best for you?
Not to fear, we’ve put together a helpful breakdown of the different schedules. After all, you want to make sure you’re choosing a fasting schedule that works well with your lifestyle and can maximize the incredible health benefits that intermittent fasting can give you.
As a general rule, the effects of intermittent fasting will vary by person, depending on the length of your fasting period, amount of food eaten during eating windows, calorie intake, body composition, and whether or not you’re choosing healthy foods.
The 16/8 Schedule
This is easily the most popular of all the intermittent fasting schedules. It combines an 8-hour eating window with a 16-hour fasting window. So, for example, only eating between the hours of noon and 8:00 p.m.
Pro: This is the most common schedule for a reason. It fits pretty seamlessly into most lifestyles, seeing as how you can choose to skip either breakfast or dinner, depending on your personal preferences. Eight hours is a solid chunk of time to get your meals without feeling socially deprived. Also, you’re sleeping during a good chunk of the fasting window, which makes it easier.
Con: 16 hours can be a long time to go without food when you’re new to fasting. After one or two weeks, most people hardly notice any more hunger pangs, but it does take your body a little while to get adjusted to this schedule.
Who it’s for: This schedule is suited for just about anyone, but especially if you’ve already experimented with shorter fasting windows, you might want to give this one a try. It tends to hit the sweet spot for most people as far as being manageable while still providing noticeable benefits.
The 12/12 Schedule
This is typically the best way to start out for anyone completely new to fasting. It used to be quite normal for people to fast for 12 hours. Dinnertime around 7pm, breakfast at 7am. Enter the advent of freezer food and late night snacks, not to mention the longer work days which cause people to stay up later.
Suddenly we are eating around the clock, and it’s wreaking havoc on our blood sugar and waistlines. Did you know that your body doesn’t actually switch from a “fed” state to the “fasted” state until about 8-12 hours after you’ve finished your last meal?
Pro: This schedule requires minimal effort. It is a great way to reset your body to what is more natural for it (giving your digestive system a break overnight). Plus, you’ll probably sleep better and you’re not likely to experience any hunger pangs with such a small fasting window. Starting here can be less daunting than jumping into long periods of fasting.
Con: Because the fasting window is relatively small, you’re not likely to see as many health benefits as quickly as you would on a plan with a longer fasting window. This is because it typically takes your body anywhere from 8-12 hours after enjoying your last meal to get to a fasted state. Only then do you enter fat-burning mode. So with a 12-hour fast, you’re only going to be in a minimal fat-burning mode, but this will be a good starting point to achieve a longer fasting duration in the near future.
Who it’s for: Anyone new to fasting or struggling with the idea of giving up food for too long.
The 20-Hour Fast (Warrior Diet)
A 20-hour fasting schedule has been popularized by the “Warrior Diet”, which was created by Ori Hofmekler. Inspired by the eating habits of ancient Spartan and Roman warriors, this plan requires you to eat all your food within a four-hour window. So, for example, only eating between 2pm and 6pm. The Warrior Diet also encourages a focus on high-intensity interval training and a diet of unprocessed foods.
Pro: Because this is a pretty condensed intermittent fasting schedule, it can work really well for folks with a hectic lifestyle. You only have to worry about preparing and eating food for 4 hours per day, and the rest of the day you can just focus on getting everything else done. Also, many people report getting very deep and restful sleep when they follow this plan.
Con: It can be difficult for some people to go a full 20 hours without consuming any calories, especially when you’re just starting out with fasting.
Who it’s for: Someone who already has some experience with intermittent fasting but who is looking for faster results. Also, there are online testimonials of folks who started with the 16/8 plan but found that they were still experiencing sugar cravings and a desire to overeat during the 8-hour window. These folks found great success with the Warrior Diet, because it is nearly impossible to overeat in a 4-hour eating window, given the limited space in your belly!
The 24-Hour Fast
Despite how it sounds, a 24-hour fast does not require you to go a whole day without eating. You will just be fasting from dinner one day until dinner the next day. Or breakfast to breakfast or lunch to lunch, depending on what you prefer. If you have dinner at 7pm tonight and don’t eat again until 7pm tomorrow, you’ve just completed a 24-hour fast.
Pro: This one can be very complementary to a busy day at work. Let’s say you have a super hectic day at the office or maybe a full day of travel. Instead of stressing about when and what to eat in the midst of your chaotic day, just take a break. Don’t worry about eating all day, until whenever you get home for dinner.
Con: You don’t want to do this one every day. It’s not recommended to do a 24-hour fast more than twice per week. But this does mean you can pick which day of the week works best for you!
Who it’s for: People whose busy schedules could benefit from eliminating the stress of finding, preparing, eating and cleaning up food for an entire day, a couple days per week.
The 5:2 “Fast Diet”
The 5:2 diet, or The Fast Diet, is a little different than most traditional intermittent fasting schedules. Instead of completely abstaining from food during any set fasting window, you instead just dramatically limit your calories for a period of time. Specifically, you eat normally for 5 days of the week. On the other two days (your choice), women limit their calories to 500 for the day, and men stay below 600 calories per day.
Pro: You never have to face a long periods of time where you’re not allowed to eat anything. This is a great plan to ease your way into the concept of fasting, without diving in all the way.
Con: Two low-calorie days means you do have to be pretty precise about counting calories twice a week, which can be a pain. That means you need to look up the caloric content of everything you’re eating, measure out your portion sizes, and keep track throughout the day.
Who it’s for: People who enjoy the process of counting and tracking amount of calories. (We know you’re out there!) This is also a great plan for anyone who is daunted by the prospect of having to face hunger pangs while fasting because you never actually have to go without food on this plan.
Tim Ferriss 3-Day Fast Protocol
Tim Ferriss has developed a three-day fasting protocol that is meant to accelerate your transition into ketosis, also known as fat-burning mode. Here’s what it looks like:
Stop eating by 6pm on Thursday. On Friday morning, drink water while going for a 3-4 hour walk. This should use up your body’s remaining glycogen stores, which will then transition you into ketosis. You don’t eat anything all day Friday and Saturday, but Tim does recommend supplementing with MCT oil or other ketone sources. You continue your fast into the daytime on Sunday and then break your fast with dinner on Sunday evening, right around 6pm. Tim’s protocol recommends doing this kind of 3-day fast once a month.
Pro: This plan has proven results for dropping people into ketosis much more quickly than other schedules. (They measure their own ketone levels to monitor their ketosis status.)
Con: Fasting for several days straight is not easy for the uninitiated. You also have to plan your day around being able to go for a long walk on the first full day of fasting. And, definitely expect to have lower energy levels as a side effect of the fast.
Who it’s for: Anyone who’s highly motivated to get accelerated benefits of intermittent fasting. If you’ve already experimented with other schedules and maybe are looking for a kickstart to break through a plateau, this might be the right plan for you.
Alternate Day Fasting
This intermittent fasting schedule is actually a hybrid plan, where you can pick either the 16/8 schedule, the 12 hour fast, or the 20-hour fast. Then, instead of following that plan every single day, you would only adhere to your chosen fasting window every other day.
Pro: This approach tends to make any intermittent fasting schedule much more manageable and customizable.
Con: It might take a little longer to see benefits since you’re not switching your body into the fasted state every day. Please note: this doesn’t mean you won’t see benefits! Plenty of people get awesome results with alternate-day fasting, and they find it much easier to sustain.
Who it’s for: Anyone not ready to commit to a full intermittent fasting schedule every day. Also, this approach definitely seems to work better for some women. You can read more about how intermittent fasting can affect women differently further below.
This is a more intense fasting approach, typically deployed in situations where there is physician oversight and you’re trying to support healthy blood sugar levels. It looks like this: Finish eating dinner by 7pm tonight, don’t eat at all tomorrow, and then have breakfast after 7am the day after tomorrow. Dr. Jason Fung has used this protocol with great success with his patients.
Pro: Excellent success rate, over the long term, for supporting healthy blood sugar levels.
Con: Quite difficult to implement. If you are on any medications, especially for diabetes, discuss your fasting plan with your healthcare providers as medication dosages may need adjustment.
Who it’s for: Primarily recommended for those trying to maintain healthy blood glucose.
Do you get suspicious when you hear people raving about a new diet that makes weight loss easy? We don’t blame you— body composition tends to be more complicated than the dieting industry leads on.
In an industry full of gimmicks and fads, there is one plan quickly rising to the forefront because it has the weight of scientific evidence behind it. An intermittent fasting diet is increasingly being praised as an eating pattern that promotes healthy weight management while also being easy to follow.
We’ve identified a few key reasons as to why intermittent fasting for weight loss works so well.
1. Secret Weapon For Managing Cravings
Considering that the mere word “fasting” can make us feel hungry, it’s a pleasant surprise for many intermittent fasting followers to discover that, after about 1-2 weeks, they no longer experience many hunger pangs during their fasting windows. And no, it’s not just a trick of the mind or extreme willpower. There’s a scientific reason why this happens.
You see, one of the most important effects that intermittent fasting has on your body is that it supports healthy blood sugar levels. (6) Normal blood sugar levels translate to less sugar cravings. (7)
The other cool thing that happens when you start intermittent fasting is that it seems to support healthy levels of a hormone called “ghrelin”. Ghrelin is known as the hunger hormone. When it’s out of whack, that’s when you feel hungry all the time. After a couple weeks of intermittent fasting and healthy ghrelin levels, you may start to notice reduced hunger pangs.
2. Natural Calorie Restriction, But Better
At the root of nearly every diet known to man is the concept of calorie restriction. We’ve all seen the formula:
Calories eaten < calories burned = weight loss
Calorie restriction is also the main reason why most diets fail over the long-term. It goes against human nature and thus is incredibly difficult to sustain.
Intermittent fasting has earned high praise on account of the fact that it naturally leads to calorie restriction, without feeling like that’s what you’re doing. We like to call it “sneaky” calorie restriction. Here’s why: a typical intermittent fasting schedule (eating only between noon and 8:00pm) usually equates to skipping breakfast. Because it’s difficult to eat more than a certain number of calories per meal, cutting your day from 3 meals down to 2 can have a noticeable effect over time.
Studies have been done comparing a group of people who were asked to restrict their calories all day, and another group that was asked to follow an intermittent fasting schedule. (8) Both groups derived similar health benefits, except the intermittent fasting group experienced more supported insulin levels.
Proponents of intermittent fasting find that it’s psychologically and biologically easier to restrict our eating to a certain time frame, as opposed to restricting our overall daily caloric intake.
3. Retain Lean Muscle Mass
Perhaps the biggest downside of many restricted calorie diets is that they have been proven to lead to loss of lean muscle mass, which actually slows down your metabolism. (9) This is really bad news for your ability to maintain any weight loss.
The good news? Research has shown that intermittent fasting actually helps you retain lean muscle mass while still losing weight. (10) Phew!
4. Better Eating Habits
When you intermittent fast, you’ll be sticking to a smaller eating window than you’re probably used to. This will naturally cut down on late-night snacking, which is often a hidden culprit of excess calories and sneaky weight gain. When you know that giving in to the munchies is just going to kick yourself out of fat-burning mode, it’s much easier to resist that late-night fridge raid!
5. It’s Sustainable
Perhaps one of the most striking things about the intermittent fasting “craze” is that people are treating it less like a diet and more like a lifestyle. So many followers find themselves not only losing weight, but feeling better and actually wanting to stick with this eating schedule. So intermittent fasting can quickly become a lifestyle change, as opposed to a crash diet.
What can I eat during intermittent fasting?
Unlike low-calorie diets, intermittent fasting is about when you eat, not what you eat (calorie intake). No need to go crazy counting or restricting calories— during your eating windows, you can basically eat whatever you want. Choose healthy foods, of course, for the best results and health benefits. Some diets, like “keto,” may even supercharge the benefits of fasting.
Possibly the two hottest diet plans around right now are the ketogenic, or “keto,” diet and intermittent fasting. Both claim to provide a wide array of health benefits well beyond weight loss. But can you follow both plans at the same time?
Yes! Not only are these two diets compatible, but they might even enhance one another. Have you hit a plateau with your keto diet? Or maybe you’re looking for a way to make intermittent fasting more manageable and effective? Well, you might want to consider taking advantage of this powerful duo.
First, let’s get a quick refresher on what exactly the Keto diet is.
The ketogenic (or “keto”) diet is essentially a low-carb, high-fat eating plan. Specifically, it prescribes eating 70-80% of your calories from healthy fat sources, 15-25% of your calories from protein, and limiting your carbohydrate calories to 5% of your diet. The average Keto dieter tries to eat less than 40 grams of carbs per day.
Eating in accordance with a keto diet is intended to shift your body to burning ketones for energy, instead of glucose (sugar and other carbs).
Here’s how it works: when you dramatically limit your carbohydrates, your body eventually goes into a state of ketosis, which means it’s using ketones for energy. Translation: your body is using fat stores for energy.
Interestingly, a keto diet actually mimics the effects of fasting, without eating fewer calories. In other words, eating a very low-carb diet can have the same effect on your body as eating nothing at all.
|Fats (70-80%)||Protein (15-25%)||Fruit/Veggies (5%)||Eliminate|
|MCT oil||Bone Broth||Cucumber||Diet Soda|
Ok, so we’ve got the basics of each of these diets down. How exactly do they benefit one another?
1. Shift into ketosis sooner
One of the primary goals of a keto diet is to get into fat-burning (ketosis) as quickly as possible and to stay there for as long as you can. When you practice periods of fasting, your fasted state has already starved your body of carbs, which means your glucose levels are lower than those of someone who doesn’t fast.
This means that when you’ve been fasting, your body can shift to burning fat reserves and ketones even sooner. And that translates to getting you into ketosis more quickly than if you weren’t fasting.
The flip-side of this is also true. Being in ketosis mimics fasting because your body is burning fat for fuel. So if you’ve been trying an intermittent fasting plan but haven’t really noticed any results, following a keto diet during your eating windows might just give you the jumpstart you’ve been looking for.
2. Support brain health and mental focus
Did you know that your brain is one of the body’s biggest consumers of energy? It’s true. And it just so happens that fat, not glucose, is the most energy-efficient fuel that your body can run on. Since both intermittent fasting and a low-carb/high-fat diet (keto) train your body to burn fat for energy, your brain can reap benefits from both these plans.
After all, we always have fat stores available to burn. So as long as your body knows how to tap into those fat stores for fuel, your brain has a constant energy source on which to run.
There’s even more good news for your brain. Studies have shown that fasting boosts the production of a protein (BDNF) that feeds your brain stem cells and promotes neural health.
3. Make both diets easier
Let’s be honest, one of the main reasons some of us are skeptical about trying intermittent fasting is that fasting leaves you feeling hungry. A keto diet, however, is known to help decrease cravings and hunger, due to the high-fat content of the keto eating plan. Fat keeps you fuller for longer.
So if you’re already following a keto diet, you may find the fasting windows of an intermittent fasting plan much easier to manage. Both eating plans are designed to help reduce cravings and hunger pangs over the long term, which also helps prevent overeating.
4. Enhance your exercise
Can you even exercise while you’re fasting? This is a common concern, but the answer is a resounding “yes!” Not only is it okay, but a growing number of studies show that following intermittent fasting and a keto diet can, in fact, enhance health benefits of your exercise program.
Both intermittent fasting and the keto diet train your body to burn stored fat for energy. This triggers a variety of metabolic adaptations that can actually increase your workout performance while you’re fasting. (11)
Worried about losing muscle? Don’t be! This study suggests that you can actually maximize your muscle gains when you train while fasting. And this study observes that when you do strength training in a fasted state, the nutrients you consume afterward will be better utilized by your body than if you hadn’t been fasting during your workout. Pretty cool!
And for those of you concerned about whether your actual workout performance will suffer as a result of fasting, not to worry. Studies have been done on Muslim athletes who fast for Ramadan, and no negative effect on performance was found. If you do decide to workout while fasting, we recommend you do it right before you start your eating window for the day.
1. Listen to your body
As with any new diet plan or exercise regimen, only you yourself can be the ultimate expert. We are all unique and will respond differently to the same plans.
If you’ve decided to follow a 16:8 intermittent fasting schedule but find yourself really struggling, tired and hungry, don’t hesitate to modify your schedule. Try shifting your eating window to later in the day, or check to make sure you’re getting enough high-quality keto food calories. And don’t forget to drink water!
If it’s still not working for you, maybe try expanding your eating window to 10 hours, or only practice an intermittent fast every other day.
2. Don’t start both at the same time
So you’re really motivated to take advantage of the potent fat-burning effects that these two diets offer. We get it! But if you’re brand new to both intermittent fasting and the keto diet, it’s not recommended that you try to adopt both at the same time. Trying to master the new eating habits of a keto diet while also sticking to the new schedule of intermittent fasting can be overwhelming, to say the least, which means you’ll be more likely to give up.
We recommend starting with an intermittent fasting schedule for approximately two weeks so that your body has time to adjust to the new pattern. At this point, your body will also be more adept at shifting into a fat-burning zone, so that when you start eating a keto diet, you’ll likely find it easier to drop into ketosis.
One of the more surprising aspects of both the Keto diet and intermittent fasting is that some seriously tough athletes claim these eating plans help to increase their athletic performance.
They just might be onto something. If you’re looking to boost your sports performance, here’s what you should know: one of the primary reasons these eating plans work is because training your body to burn fat can help you recover from exercise more quickly. (12) And if you eat a keto diet and follow an intermittent fasting schedule, then your body becomes increasingly more efficient at switching over to fat-burning mode. The easier it is for your body to burn fat, the better your athletic performance and recovery time.
There’s a growing number of endurance and elite athletes who have incorporated fasted training into their programs. And if you’re looking to add lean muscle mass, regular fasting has been shown to help with muscular development.
Despite what it might sound like, intermittent fasting is NOT about starving yourself. So what exactly can you consume while following an intermittent fasting plan? And are there drinks that can make it easier or more effective? We wanted to get to the bottom of that question, and here’s what we discovered.
Intermittent fasting breaks your day into two parts:
- Eating (feeding), and
- Not eating (fasting)
There are entirely different guidelines for what you can eat and drink, depending on whether you’re in your eating window or fasting window.
During your fasting window, you need to refrain from consuming any food or beverages that contain calories. So….. no food. But you have several beverage options, and these are important because it is critical to keep yourself hydrated while fasting. Plus, there are certain drinks that can even help enhance the benefits of your intermittent fasting plan. Sweet!
Water is always a great choice. Drink water all day long, every day. It can be still or sparkling, whatever you enjoy. You can also add a squeeze of lemon or lime to your water, or infuse a pitcher of water with cucumber or orange slices. But make sure you stay away from any artificially-sweetened water enhancers (like Crystal Light)!
Technically, black coffee is a calorie-free beverage, and many people drink it during fasting with no adverse effects. There are some people who experience a racing heart or upset stomach if they use coffee during a fast, so monitor your own experience. You can drink caffeinated or decaffeinated coffee, but any sweetener or milk is prohibited. Spices like cinnamon are totally fine!
Bonus: black coffee might actually enhance some of the benefits of intermittent fasting. This study demonstrated that taking in caffeine can increase ketone production, which means you’re more likely to slide into fat-burning mode even faster.
3. Bone Broth
Bone broth (or vegetable broth) is recommended for anytime you decide to fast for 24 hours. While it has calories, it does not contain any carbohydrate, so it helps you stay in ketosis. Beware of canned broths or bouillon cubes that contain artificial flavors and preservatives. A good homemade broth, or one made by a trusted source, is the way to go.
Tea just might be the secret weapon that not only makes your fasting plan easier but also more successful. All types of tea are great to drink during a fast, including green, black, white, oolong and herbal. But green tea, in particular, can help support healthy weight management. (13) And tea, in general, can boost the effectiveness of intermittent fasting by promoting gut health and probiotic balance.
5. Apple Cider Vinegar
Apple cider vinegar seems to help to support healthy blood sugar and digestion (14) .It may actually enhance the effects of your intermittent fasting plan!
6. Drinks to Avoid
There are a few beverages that you might not realize are capable of breaking your fast. That just means that if you consume these, you will knock your body out of the fat-burning mode that intermittent fasting put you in: diet soda, coconut water, almond milk, and alcohol!
Even though diet soda technically doesn’t have any calories, it’s unclear how artificial sweeteners might impact fasting. Alcohol has calories. And coconut water and almond milk both tend to be very high in sugar. Sugar equals carbs, so as soon as you consume these, you are no longer considered to be fasting.
If you’re trying to stick to a new intermittent fasting plan, you may want to take advantage of the oldest fasting aid around – tea! Used for centuries by monks to help support their fasting journeys, tea can make your fasting experience more enjoyable and manageable.
Considered to be a health elixir in many ancient cultures, this simple drink is a powerhouse enhancer for your intermittent fasting lifestyle. You know all those incredible proven benefits you can get from intermittent fasting? Well, drinking the right kind of tea can help you stay fasted more easily, increasing your chances of experiencing those benefits.
It’s no secret that men and women respond differently to diet and exercise programs. Intermittent fasting is quickly becoming the hottest trend for achieving weight loss and a host of other benefits. So, we wanted to investigate whether IF for women should follow the same type of fasting plan as men. Here’s what we found.
There definitely seems to be a variety of valid perspectives on this topic, as is the case with most health matters these days! Overall, there doesn’t appear to be any evidence that intermittent fasting is inherently bad for women. However, there are some women who do experience negative effects. It is possible that women will respond better to certain intermittent fasting schedules than others, and we’ll dig into what those schedules are below.
When trying to get to the bottom of how intermittent fasting works for women’s bodies, you’ll find that the answers fall into two very distinct categories. There is the science and research, which tells us that fasting is safe and effective for women. Then there are the personal experience testimonials, which tell us that certain intermittent fasting schedules can be tough on some women, while others seem to work great. We’ll break this information down for you here. Bottom line: you just need to try for yourself and determine what feels right for you!
There are two primary areas of concern that many women have before starting a fasting plan: Is it safe? And will I get the same benefits that men experience?
Safety of fasting for women
Probably the most common concern is that women’s hormone levels will be adversely affected by intermittent fasting. Indeed, one rat-based study did show that intermittent fasting can cause hormonal imbalance in female rats. (15)
Scientific research on humans, however, has shown just the opposite. Short-term fasting (defined as 72 hours in this study) seems to have no effect on a woman’s hormones or menstrual cycle, but more studies are needed. (16)
Caveat: women who already have very low body fat levels are not likely to be good candidates for intermittent fasting. (Neither are men with excessively low body fat!) The fat loss triggered by intermittent fasting can cause a woman with already low levels of body fat to experience amenorrhea (loss of menstrual cycle) or difficulty conceiving. A woman with normal and healthy body fat levels is not likely to experience any serious changes in her reproductive hormone profile while fasting. (16)
Also, pregnant and breast-feeding women should never fast.
Benefits of fasting for women
Virtually all studies on fasting confirm that men and women both experience the same benefits. In one particular study, men and women were shown to have very similar rates of weight loss during fasting. (17)
Recognized fasting expert Dr. Jason Fung has treated nearly 1000 patients with intermittent fasting, and he concludes that women actually tend to do better than men when it comes to successfully seeing results. In his experience, the highest success rates for weight loss with intermittent fasting actually occur when a husband and wife follow the plan together.
A quick Google search will lead you to a catalog of women’s experiences with fasting, which ranges from transformative to downright awful. Of course, just about any diet or fitness plan out there can result in this wide spectrum of experiences. It’s because we’re all so beautifully individual! But we wanted to highlight a few key points to guide you in your decision of whether intermittent fasting is right for you, and which schedule you should choose.
1. Use a Modified Fasting Schedule
According to the weight of testimonials, the popular 16-hour fast (16/8 schedule) may not be ideal for some women. Many women seem to respond better to intermittent fasting when they adopt shorter fasting windows than men, and stick to an alternate-day fasting schedule rather than multiple consecutive days. Here’s what alternate-day fasting might like:
Mondays, Wednesdays, and Fridays are fasting days, so you would only eat between 10:00am and 8:00pm. That’s a 14 hour fast with a 10-hour eating window. Then on Tuesdays, Thursdays, and Sundays, you would follow a normal eating routine.
You might find this method referred to as the “Crescendo Method” of intermittent fasting. It gives your female body a chance to adapt to the new stresses of intermittent fasting, and it is more likely to help you achieve long-term benefits. If you’re following the method for 2-3 weeks and feeling good, you can always add one more day of fasting per week, or maybe try extending your fasting window by one hour for one day per week.
2. Monitor Yourself
You should always pay close attention to how your body is responding to any changes to your diet or exercise routine. But with intermittent fasting in particular, you want to keep an eye out for any of these changes:
- Increased stress
- Trouble falling or staying asleep
- Hair loss
- Anxiety or depression
- Low energy
- Slowed digestion
- Muscle pain or increased soreness
- Mood swings
- Loss of sex drive
- Loss of menstrual cycle
- Feeling cold
If you are noticing one or more of these symptoms in a pronounced way, please stop your fasting plan immediately. If you’re starting to feel like any of these symptoms are just starting to happen, you can try to adopt a more conservative and gentle fasting approach. That means taking a couple days off from fasting or making your eating window a couple hours longer.
3. Make Sure You’re Getting Enough Protein
The main reason why intermittent fasting can be trickier for women than men is because of its effect on hormone balance. And one of the key ingredients to keeping hormones balanced is protein!
Eating protein provides your system with amino acids, which are the building blocks of the estrogens (estriol, estradiol, and estrone) in your body. If you’re not getting enough protein and amino acids, your body can’t make enough of these estrogen metabolites. (18)
In general, women tend to eat less protein than men. And when women adopt a shorter eating window, they are more likely to wind up consuming even less protein.
So if you decide to give intermittent fasting a try, it can be helpful to make sure you’re getting a solid helping of high-protein foods at every meal during your eating window (think fish, beans, quinoa, protein shakes). You can also consider taking a BCAA (branch chain amino acids) supplement during your fasting days.
4. Use Resources and Support Groups
If you’re eager to give intermittent fasting a try but are nervous about what to expect, don’t feel like you are alone! There are quite a few awesome support groups and message boards on Facebook and Reddit. Just search for “intermittent fasting for women” and see which groups appeal to you. It can be very helpful to read through the personal experiences of other women, or to be able to reach out to them with questions about your own journey.
If you’re still not sure this intermittent fasting thing is for you, we want to take a minute and answer the most common concerns.
How can an eating schedule have so many benefits?
Turns out, the time we spend eating can be just as important to our health as the foods we are eating. Here’s why: at any point in time, your body is either “fed” or “fasted.” While you might assume that your “fed” time only includes the time spent eating, it actually refers to the approximately 8-12-hour period of time in which your body is digesting and absorbing the food you’ve eaten.
So let’s say you finish eating dinner at 6pm. Your body actually remains in a fed state until sometime after midnight. Only then does your body enter the fasted state. Assuming, of course, you haven’t had any nighttime snacks after dinner!
Why should you care about whether or not you’re in a fasted state? Because that is where all the good stuff happens. Not only does your body shift to burning stored fat once it enters the fasted state, but a number of other metabolic changes happen here that are responsible for the wide array of health benefits described above. (19)
Getting into the fasted state is actually pretty rare for most of us. That’s why the sole purpose of intermittent fasting is to allow your body to get into a fasted state and stay there for a couple hours.
When should I eat?
Hands down the most popular intermittent fasting plan is called the 16:8. It means you fast for 16 hours and eat during the remaining 8 hours of your day.
The best part is that you can start your 8-hour window anytime you want. For example, you can try skipping breakfast and only eating lunch and dinner. Need your breakfast? No problem, just skip your dinner instead. Experiment with different windows until you figure out what works well for your lifestyle and personality, and what makes you feel physically at your best.
What should I eat?
Because intermittent fasting plans are purely concerned with WHEN you eat, it’s easy to get confused about WHAT you should be eating during your eating window. Technically, intermittent fasting has no rules about this. You’ll find many intermittent fasting guides that tell you to eat whatever you want.
That being said, it’s common sense that the benefits you reap from fasting will be limited by your food choices while eating.
If you happen to be following a Ketogenic (“Keto”) diet or have been considering one, it actually compliments intermittent fasting very well. You can read more about combining the two above.
What should I drink?
During your fasting window, you need to refrain from consuming any food or beverages that contain calories. So….. no food. But you have several beverage options, and these are important because it is critical to keep yourself hydrated while fasting.
Further above, we’ve got a quick-start guide to the drinks that can help your fasting journey.
Won’t I be tired while fasting?
This super common concern about fasting has actually been disproven time and time again.
Because intermittent fasting provides your body with more breaks from the digestive process, it will actually give you more energy and boost your productivity.
Isn’t fasting bad for my metabolism?
Quite the opposite! Long-term starvation diets can certainly harm your metabolism, but an intermittent fasting schedule can actually help to boost the metabolism. (20) And while many weight loss programs result in loss of lean muscle mass, intermittent fasting only targets your stored fat, so you get to preserve all your muscle tissue, which is so critical in keeping your metabolism humming along. (10)
I’m terrible at diets, how do I stick with this one?
You’re not alone. But people who try intermittent fasting overwhelmingly discover that it is surprisingly easy to implement. The main reason diets fail is because behavior change is hard.
But with this, there’s only one rule to follow, and there’s zero advance planning.
In other words, it’s simple enough that you’ll actually be able to keep it up! There’s even scientific research indicating that “subjects quickly adapt” to an intermittent fasting plan, making it a highly effective technique. (21)
Is intermittent fasting really for everyone?
If you are a woman, it’s possible that intermittent fasting may affect you differently. In general, it seems that women tend to respond better to using a schedule that has a wider eating window. For example, some women have noticed increased health benefits by using a 10-hour eating window with a 14-hour fast, instead of the 16:8 plan popularized by male bodybuilders. You can read more in-depth information about intermittent fasting for women above.
As with any diet or exercise plan, we recommend trying different options and listening to your body to see what works best for YOU and supports your overall health. There’s a fantastic all-female intermittent fasting Facebook group here for you to check out if you’d like to connect with other women about their experiences.
Also, if you are diabetic, hypoglycemic, have any issues with blood sugar regulation, are pregnant or breast-feeding, or have a history of an eating disorder, intermittent fasting may not be for you. You should talk to your doctor before making changes to your eating schedule.