We’ve all seen those shocking ‘before’ and ‘after’ photos of someone who used Intermittent Fasting (IF) to Shed 50 Pounds. Or those tweets about how IF helped stabilize blood sugar. But, is intermittent fasting really that great at helping people improve health? And if so, is it safe? Read on to learn the pros and cons of using IF as part of your lifestyle, and to figure out if IF is right for you.
Takeaways:
- Intermittent fasting is an ever-growing topic in the public and in research.
- Research shows IF does appear to provide at least some health benefits.
- IF is not for everyone and if you do want to try it, you can tailor it to your needs.
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So, what exactly is intermittent fasting?
For several years now, IF has captivated the public and researchers alike in terms of its purported and research-supported benefits. To understand IF, we must first understand fasting.
In short, fasting is the state you’re in when you’re not eating or drinking any calories. Ideally, this state is brought on voluntarily (such as when you’re sleeping, you’re preparing for lab work, or if you’re choosing to use intermittent fasting). It can also be brought on when you’ve forgotten your lunch at home, and you’ve forgotten your wallet, and not one of your co-workers has a penny to lend you, so you’re left with a grumbling stomach all day… definitely not speaking from experience.
Regardless of the reason for your fast, it changes up your metabolism a bit. Your metabolism is optimized to keep your body running by using the food you eat throughout the day. When you’re not eating, such as when you’re asleep, your body still needs energy, so your metabolism switches and breaks into the energy stores found in your muscle and fat cells and uses those up.
Typically, you’d wake up feeling hungry; this is because your body has used up the food you ate for dinner the previous night and has started to tap into those other energy stores. Then, you’d eat breakfast which would partly replenish your energy stores and fill your stomach up with food to be used immediately for other energy needs throughout your body.
Now that we understand fasting, let’s spice it up and throw in ‘intermittent.’
Intermittent fasting is simply when you use fasting following a specific schedule. There are several different types of IF you could use:
- Some people prefer the 16:8 fasting method. For this one, you simply choose 8 of your 24 hours in a day to use as your eating window. In those 8 hours, you might choose to have two meals and a couple of snacks. For the other 16 hours, you’d fast! This is one of the more common IF methods used, as the 8-hour window can easily be shifted to fit your needs. If you’re not much of a breakfast person anyway, you might start your eating window with lunch at noon and end it with dinner at 8pm. Or, you could have breakfast at 10am, lunch at 1:30pm, and dinner and dessert at 6pm; whatever works for you. Another option is to change it to a 14:10 pattern, where you extend the eating window by two hours. The beautiful thing with IF is you can make it your own!
- Alternate day fasting, or ADF, involves fasting every other day in an effort to reap the benefits of fasting. On eating days, you’d strive to eat normal, balanced meals and snacks. On fasting days, you could do a strict fast and avoid all food and beverage calories, but it’s more popular to restrict calories. Straight-up fasting so frequently can lead to a lot of issues, such as headaches, stomach discomfort, dizziness, overeating, and difficulty concentrating.
- Then there’s 5:2 intermittent fasting, where you eat a balanced diet for 5 days and fast for 2 days out of the week. Similar to ADF, on fasting days with the 5:2 method you can opt for a true fast or stick with the recommended calorie restriction. The 5:2 method can be a good way to ease yourself into ADF if you feel ADF is calling your name but you’re not ready to fast every. other. day.
- Overnight fasting is one of the gentler methods of fasting. It is easier to do if you don’t work a night shift or are not a night owl. Simply stop eating after your last meal of the day, and don’t eat until your first meal the following day. This means no midnight snacking or late-night runs to the pizza shop on these days. Side note: Have you ever wondered why breakfast is named as such? You’re breaking your overnight fast!
The great thing about fasting is that it can be tailored to your needs. No single method is perfect for every person, and fasting, in general, is not recommended for everyone (more on that later). Creative license is totally encouraged with fasting and finding patterns that work for you.
What are the pros and cons of IF?
As with any eating pattern or diet out there, there are going to be pros and cons to using IF in your life:
Pros of intermittent fasting
Weight loss
One of the more popular benefits of IF is weight loss. In the last decade, the fittest people in entertainment, sports, and even business have used IF to achieve weight goals, including Terry Crews, Jack Dorsey, Kourtney Kardashian, and Joe Rogan. IF is a popular prep diet for actors in Marvel or DC movies, like Josh Brolin who’s also in the new movie Dune. He’s pulled some serious diet adjustments, like skipping and scheduling his meals.
Decreased risk of chronic disease
IF has been linked to a decreased risk for chronic disease in multiple studies. Mark Mattson, PhD, a neuroscientist at Johns Hopkins, says, ‘Many things happen during intermittent fasting that can protect organs against chronic diseases like type 2 diabetes, heart disease, age-related neurodegenerative disorders, even inflammatory bowel disease and many cancers.’
In an interview, the director of the Massachusetts General Hospital Weight Center, Angela Fitch, MD said IF, ‘may have other benefits, too, such as decreasing cancer risk, managing autoimmune diseases and even adding years to a person’s life.’
Preliminary research indicates IF may be beneficial in improving health outcomes in people who have diabetes, including weight loss and normalization of blood glucose levels. A review published in the American Journal of Medicine in 2020 also says IF may be linked with a decreased risk for heart disease by improving markers such as weight control, blood pressure, lipid panels, and diabetes.
May promote brain health
IF may help keep your brain healthy. While there is not too much research in people, mouse studies indicate fasting may improve blood lipid levels, which in turn may provide neurological protection and prevent age-related memory declines.
Once all your glucose stores are used up during a fast, your metabolism switches to start burning up your fat stores. This metabolic switch has been found to be beneficial to your brain by promoting neuroplasticity and increasing your brain’s resiliency to injury and disease, each of which can promote clarity of thought. Struggling with brain fog? IF may be the answer you’ve been searching for! (But also, if brain fog is an issue for you, but you don’t like the idea of food restriction, new research suggests you can snack your way to a clearer mind!)
Cons of intermittent fasting
High dropout rates
Dropout rates from IF can be very high and with good reason. The word ‘fasting’ typically does not evoke feelings of satisfaction and contentedness. Going long periods of time without eating can lead you to feel hungry, tired, irritable, and just plain miserable if your body isn’t used to a strict schedule. Old habits die hard and forcing yourself into a new eating schedule requires a lot of self-control. As Tracy Lockwood explained in a Men’s Health interview, ‘if eating at scheduled times during the day is a habit that our body has inherently become used to, it’s going to be hard to remove food during those scheduled times… [and] especially hard to adhere to — causing people to tap out.’
Does not promote mindful eating habits
IF does not promote mindful eating habits (i.e. listening to and honoring hunger/fullness cues) which can lead to food obsession and binging. Dr. Frank Hu, from the Harvard T.H. Chan School of Public Health, points out, ‘it’s human nature… to want to reward themselves after doing very hard work, such as exercise or fasting for a long period of time, so there is a danger of indulging in unhealthy dietary habits on non-fasting days.’
Additionally, your body is not able to tell if a period of fasting is actually the beginning stages of a prolonged famine. When your body senses a prolonged calorie deficit, your wiring tells your body to eat as much as it can the next time it has the opportunity, which means you are more likely to overeat when you break your fast.
Can impact social eating
A major downside to IF can be the impact it has on your social life, especially if you choose to follow a stricter regimen. Because, in all honesty, most social interactions revolve around food to some extent! Staying dedicated to ADF, for example, may be difficult when you’re invited to a birthday celebration on a fasting day. And if you choose to socialize on fasting days regardless, and lean on willpower to not eat anything, you’ll likely still feel tired or irritable since you’ll be operating on very few calories.
Loss of muscle mass
While IF can be an effective strategy for weight loss, all the weight you lose may not be from body fat alone. Restricting your food intake, and especially your protein intake may also impact your lean muscle mass. In other words, you might find that you lose muscle! Your muscle proteins are constantly being broken down and replenished by your diet, so restricting your intake of those essential nutrients with intermittent fasting isn’t thought to be the best for anyone looking to maintain or grow muscle. However, more research needs to be done to determine exactly how fasting can impact your muscle mass.
Increase in stress (cortisol levels)
Finally, it’s important to note that IF may also impact your hormones, specifically your “stress hormone” cortisol. Several studies have found that being in a state of calorie restriction can raise your cortisol levels due to the stress that it puts on your body. Unfortunately, high cortisol levels can also change your metabolism and make it harder for you to lose weight if left unchecked!
How to know if intermittent fasting is right for you
If you fall into any one of the following categories IF is probably not right for you. Speak with your doctor before trying IF if you:
- Are pregnant
- Are less than 18 years old
- Are underweight
- Have a history of disordered eating or are at risk of developing an eating disorder
- Have diabetes
- Are on any blood pressure or heart disease medications
If you do not fall into any of the aforementioned categories, you should still proceed with caution. Test out different types of IF to see which pattern works best for you and the lifestyle you want. If you find yourself getting hangry all the time, or just not feeling well IF isn’t for you. Remember, no single eating pattern is right for everyone. So, the fact IF worked for Josh Brolin does not mean it should work for everyone.
With that being said IF does have the potential to work for most people and bring some positive health benefits. If you’ve got the time and energy to do some experimenting, give IF a shot.
There are a bunch of different apps that can help you get on track with incorporating intermittent fasting into your life. Apps like Simple, the Ate Food Diary, and Zero each have awesome features to help you stay on track with the healthy habits you are trying to establish, including intermittent fasting!
And, as always, don’t hesitate to reach out to a healthcare professional, like a doctor or a registered dietitian, for any questions and concerns you have.
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