Science-backed Health Benefits of Intermittent Fasting
The concept of forgoing food for prolonged periods of time is nothing new, but research is still uncovering some of the incredible benefits of fasting.
If you’re a food lover, the idea of fasting may sound overwhelming or downright torturous. The good news is, there are many fasting protocols that make it pretty painless to abstain from food in short bursts so you can reap all of the associated benefits.
Unlike prolonged fasts, intermittent fasting gives your body short breaks from food to focus on rest and repair.
Intermittent fasting (IF) is a type of fasting protocol that typically lasts anywhere from 10 to 24 hours. Unlike a typical eating schedule, when you intermittently fast, you’ll allow yourself eating windows while refraining from consuming food or caloric beverages the rest of the day.
Following an IF protocol comes with a range of benefits as it gives your digestive system a break and allows your body to repair and rebuild.
By abstaining from food intake, you also give the systems in your body like detoxification and metabolism a rest — giving yourself a little reboot.
What’s more, many of the benefits of following a ketogenic diet apply to IF due to the fact that fasting often requires you to burn through your glucose stores and enter a state of ketosis as your body searches for new sources of fuel.
IF can be used daily, a couple of times a week, or as little as once a month, depending on your goals and how well your body responds to fasting. There are a variety of different protocols, so you can choose which type of fasting schedule best fits your body and lifestyle.
The concept of taking breaks from food and giving yourself a period of fasting is nothing new. In fact, across the globe, people have been using fasting protocols for both religious and health purposes for thousands of years.
For example, during the month of Ramadan Muslims are required to fast every day from dawn to sunset, and it’s believed that the practice of fasting in Islam goes back to 610 A.D[*].
Hippocrates recommended fasting as far back as the 5th century B.C. for patients exhibiting certain symptoms of illness. And in Ayurvedic medicine, the practice of fasting (known as pratyahara) has been used for five thousand years as a way to give the body a break from anything taken into the body.
Today, there are several different fasting protocols that people have found to be helpful. For some, a longer fast done once or twice a week is ideal. For others, shorter daily fasts work best.
Regardless of the length of your fast, or your eating window, fasting is a way to take some pressure off your digestive organs and allow your system some time for rest and repair.
#1 Enhances Autophagy
Autophagy is a process by which your body removes old or dysfunctional cells or cell parts. This natural process allows for the degradation and recycling of your cells, keeping you young and healthy on a cellular level[*].
In other words, autophagy is your body’s way of cleaning out the old to make room for the new.
This process helps to protect your body against a variety of ailments from neurodegenerative disease to infections and malignancies[*].
#2 Boosts Fat Loss While Retaining Muscle Mass
One of the unique benefits of fasting is your body’s ability to retain muscle mass while losing body fat at the same time.
Typically, when you lose fat mass, a fair amount of muscle will go along for the ride. With IF, however, a hormonal shift occurs that allows for your body to lose fat while holding on to your precious lean muscle.
This is due to the interplay between two hormones — HGH (human growth hormone) and insulin.
Insulin, which is normally present when there is glucose in your bloodstream, remains low during a fast. HGH, which has an inverse relationship with insulin, remains high. Low levels of insulin are associated with fat loss, as are high levels of HGH — which provides you with the ideal conditions to burn fat[*][*][*].
HGH also has a muscle-sparing effect, as do ketones. Since a fasted state is marked by an increase in both ketone bodies and HGH, you not only get to burn fat while fasting, but your muscle stays put as well[*].
#3 May Prevent and Treat Cancer
While human studies are still lacking, there is a significant amount of animal research that shows that fasting can suppress cancerous tumors’ growth while also supporting the efficacy of chemotherapy drugs[*].
Interestingly, in chemotherapy studies, fasting also seems to provide a protective mechanism for healthy cells — shielding them from the toxicity that comes with chemotherapeutic agents. It’s proposed that fasting can enhance the stress-resistance of healthy cells while creating more sensitivity in tumor cells to the chemo[*][*].
#4 Improves Insulin Sensitivity
Insulin resistance, a state where your cells are no longer sensitive to the effects of insulin, is known as a primary driver for type 2 diabetes. However, insulin resistance also plays a role in heart disease, Alzheimer’s disease, and inflammatory conditions[*][*].
When you fast, your insulin levels naturally fall as you abstain from taking in food and triggering the release of this hormone. At the same time, however, fasting appears to increase your cells’ sensitivity to insulin, and thus improves your body’s overall blood sugar control[*].
#5 Boosts Brain Health
Research shows that IF can improve something called neuroplasticity in your brain. Neuroplasticity can be described as your brain’s ability to reorganize its synaptic wiring, allowing you to evolve and learn throughout your life[*].
Along with your ability to learn and evolve, IF can also help to improve cognitive function through its anti-inflammatory activity and the production of ketones. This may be of great importance as you age, as many age-related neurological diseases are marked by the brain’s inability to use glucose efficiently[*].
#6 Lowers Inflammation
Inflammation is a root cause of almost every disease state and metabolic imbalance out there. While low levels of inflammation are a regular part of your immune process, ongoing chronic inflammation can be detrimental to your health.
Research shows that IF can result in lower levels of several inflammatory markers, including C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α)[*].
CRP is associated with an increased risk for inflammatory diseases like rheumatoid arthritis, lupus, or heart disease[*], while TNF is associated with conditions like ankylosing spondylitis, inflammatory bowel disease, and psoriasis[*].
#7 Slows Aging
Aging is a natural process that your body goes through as you get on in years. Your cells and tissues slowly start to break down more, your metabolic processes become less efficient, and the repair mechanisms in your body slow down.
While aging is a fact of life, there are ways to modulate the rate at which your body slows down, potentially helping you to live longer.
IF has been shown to upregulate several pathways that support longevity, and may decrease the rate at which your cells age, including processes like autophagy, DNA repair, and mitochondrial health[*].
While more clinical trials need to be conducted, animal studies show that imposing fasting periods can increase the lives of the animals, thereby enhancing their longevity[*].
#8 Supports Heart Health
The CDC states that one person dies every 37 seconds in the United States from cardiovascular disease[*]. Factors like inflammation, oxidative stress, blood lipids, and blood pressure all play a role in the progression of heart disease — most of which can be prevented with lifestyle interventions.
IF may be one such intervention. Research shows that following an IF protocol can lower your blood triglycerides, lower blood pressure, and reduce inflammation (thereby inhibiting plaque formation)[*][*][*].
If the concept of fasting sounds overwhelming, rest assured that there are several different types of fasting protocols you can follow. The shorter fasts are often the best place to start as they’re much less intimidating.
As you get used to fasting, you may find that doing one or two longer fasts each week works better for you; either way, you’ll still reap the benefits of abstaining from food for short periods of time.
Here are some of the most common fasting protocols:
#1 Eating Windows (Shorter Fasts)
Shorter fasts involve eating windows where you only allow yourself to eat within a specific timeframe. This type of short-term fasting often referred to as time-restricted eating, can be followed daily as it still allows you to consume food each day within your eating window.
The most common eating windows are 8 to 10 hours, with a 14 to 16 hour fast within a 24 hour period. These are also referred to as the 16:8 or the 14:10 method.
For a 16:8 fast, this could look like:
- 10 am breakfast
- 2 pm lunch
- 5:30 dinner (done by 6 pm)
Then, from 6pm at night you’ll begin your fast until you break it at 10am the following morning.
Eating windows is a popular fasting technique because it allows you to keep your eating schedule pretty regular, and you don’t have to go without food for too long.
And if you’re wondering if you’ll get the same benefits with a shorter fast, research shows that an eating window up to ten hours long can result in weight loss, lower blood pressure, lower cholesterol, improved sleep, and reduced risk for diabetes and heart disease[*].
#2 Longer Fasts
You may prefer to do longer fasts once or twice a week and maintain your regular eating schedule for the rest of the week. Longer fasts, often 24-hours or more, are a great way to get the benefits of fasting in with just a couple days of altered eating.
While going a full 24-hours may sound like a long time to abstain from food, you can actually schedule your fasts so that you still get to eat each day.
For example, if you were to stop eating after lunch on Monday (let’s say 2 pm), and then wait until lunch on Tuesday to eat again (2 pm again), you’ve gone a full 24-hours without food. This method allows you to have at least one or two meals each day, which is a lot less intimidating than going a whole day without any food.
For the more advanced faster, you may want to try a full day without food, which would end up being closer to 32 to 36 hours of fasting if you include two nights of sleep.
#3 Alternate Day Fasting
Alternate day fasting (ADF) involves alternating between eating on a regular food schedule day and following a fasting protocol every other day.
With ADF, you can choose to go without food entirely on your fasting days, or you can cut your calories down to 25% of your normal intake every other day.
Research shows that those who opt for 25% of their typical caloric intake on “fasting” days can still experience weight loss and heart health-boosting benefits[*].
An example of ADF for someone who consumes 2000 calories a day may look like:
- Fasting day: 0 calories to 500 calories for the day (0-25%)
- Feeding day: 2000 calories for the day
There are a couple of things to keep in mind with ADF:
#1 Since your fasting period will include the night (while you sleep) of your previous feeding day as well as the night through your fasting day, the total number of fasted hours ends up being around 36.
While there are many benefits to alternate day fasting, one potential downside is the intense hunger that many people feel when following a full 36-hour fast. If you’re someone who tends to get hangry, following a time-restricted eating protocol may be more practical[*].
#2 On feeding days, you can technically eat whatever and however much you like. For some people, this may trigger binge eating, so continue to be mindful of your food choices on feeding days.
It’s okay to go over your typical daily caloric intake on these days (especially if weight loss isn’t your goal), but try not to look at your fasting days as a get out of jail free card for your eating days.
#4 5:2 Fasting Diet
The 5:2 diet is a fasting protocol that includes five days of normal eating, with two days of fasting a week.
There are a couple of different ways you can set up your 5:2 fasting schedule. For Instance, you could fast for two days in a row (48-hour fast), or you could pick two days during the week (Monday and Thursday, for Instance) to forgo food.
It’s recommended that you pick the same two days each week, if possible, to keep things simple. However, if it works better for your schedule to mix it up, that’s fine, as long as you fast for two days a week.
The guidelines for 5:2 fasting are as follows:
- Two days a week, you either fast completely for 24-hours or follow caloric restriction and only consume 500-600 calories (partial fast).
- Five days a week eat normally (no restricting and no overeating to make up for fasted days).
- You choose when to fast — go for the full 48 hours, or break your fast up into two 24-hour fasts.
The 5:2 diet is less extreme than alternate-day fasting because instead of fasting every other day, you’re only taking two days a week off of food. However, this is still a more extreme option than fasting windows where you’re still getting food every day.
Breaking up your regular eating pattern with periods of fasting not only imparts benefits like fat burning and weight management but has a positive impact on several health conditions
From managing blood sugar levels to lowering inflammation and oxidative stress, following an intermittent fasting protocol is one of the best ways to optimize your body for health and longevity.
To truly reap the benefits of IF, however, be sure to focus on healthy foods during your eating windows. It’s very easy to see fasting as a hall pass for overeating or to indulge in unhealthy foods — but try to abstain from this type of thinking.