What is Intermittent Fasting?
Intermittent fasting has been a hot topic in the health and wellness world lately, but it’s more than just a passing trend. Research into the benefits of fasting is growing, the possible uses both for chronic illnesses and overall wellness are expanding, and we’re beginning to understand that being mindful of when we eat in addition to what we eat really is an important part of a healthy and balanced lifestyle.
The body has an extraordinary ability to heal itself, if we let it. Intermittent fasting is, at its core, a method of supporting our innate healing and detoxifying mechanisms. We can think of the body as having two main settings: there’s what it does when we’re eating, which includes building cells and tissues as well as storing nutrients for future use, and then there’s what it does when we’re fasting, which includes clearing out dead and diseased cells, detoxifying, and repairing cells, among other essential functions.
When our routine essentially involves eating from the time we wake up to the time we go to sleep, we are not allowing our bodies enough time to really focus on cleansing and cellular repair. This is akin to the difference between rushing around to dust off a few surfaces before guests arrive, and taking several hours to thoroughly clean the house. This can cause a number of negative effects, which may worsen over time if we don’t change our habits. Intermittent fasting is a tool that we can use to implement the thorough, deep clean into our regular lives.
It may sound daunting at first, but there are a number of effective and sustainable ways to build fasting into your routine. We all fast overnight while we’re asleep. A simple intermittent fasting routine extends that overnight fast by skipping breakfast, eating an earlier dinner and not snacking afterwards, or some combination of both.
What are the Benefits of Intermittent Fasting?
The benefits of intermittent fasting are widespread (1). In addition to the cellular repair processes that are initiated during periods of fasting, studies have found reduced inflammation (2), reduced oxidative stress, improvements in metabolism, improved regulation of hormones, reduced blood pressure, improved blood sugar control, increased production of new brain cells (3), and improved cardiovascular function (4). Fasting may also help us to live longer (5, 6).
A fundamental benefit of fasting is the increased cellular cleansing and repair that occurs. One of the most important processes involved in this repair is autophagy, which literally means “self-eating”. Essentially, the body searches for cells that are dead or dying, damaged, or toxic, eats and breaks them down, and repairs and restores the viable parts for use as energy. This process is stimulated by periods of fasting, and is responsible for many of the healing benefits of the practice (7).
Fasting also helps us to make better use of our energy. Digestion is a tiring process, especially for an overburdened body. It requires a significant amount of energy, and when we’re eating all the time, we’re constantly diverting focus from other important internal activities that require that energy. A great example of this struggle in action is what often happens when we’re battling a virus or infection: we lose our appetites. This is the body’s way of telling us that it needs to focus more of its energy on immune system function (and less on digestion) so that we can recover.
In cases of more chronic fatigue and overload, we may not receive signals from our bodies asking us to give them a break from digestion, but the energy drain manifests itself in different ways, from brain fog to a slower metabolism to difficulty regulating blood sugar. Fasting gives us a break from digestion, and lets us refocus our energy on the many other functions that are necessary to keep us healthy.
Intermittent fasting can also help with hormone resistance. One of the possible effects of being bogged down by toxins and inflammation as many of us are is becoming somewhat desensitized– or resistant– to the hormones that we’re producing. Insulin resistance is a well-known example that we’ll expand on further down, but this occurs with other hormones as well. When these hormones essentially knock at the door of the cell receptor site that will allow them to work, and that door doesn’t open– because it’s exhausted and overburdened– it causes us to overproduce the hormone. Intermittent fasting helps to resensitize our systems to these hormones including insulin, the “stress hormone” cortisol, and thyroid hormone.
Intermittent Fasting and the Brain
When we allow our bodies the time and energy to focus on cleansing and repair by fasting, one of the most exciting benefits that we often see is a clearer and sharper mind. Many individuals feel like the lights have been turned back on, with reduced brain fog and sluggishness, increased focus, and improvements in memory (8).
In addition to helping us to regain mental clarity through cellular repair and detoxification, fasting increases our levels of IDE (Insulin Degrading Enzyme) which, in addition to lowering insulin levels, works to break down toxic plaques that can build up in the brain and have been linked to neurodegenerative disorders including Alzheimer’s.
Fasting also boosts our creation of new nerve cells as well as an important protein called BDNF (Brain Derived Neurotrophic Factor) (9), which may have benefits for depression, Alzheimer’s, and overall brain health.
Intermittent Fasting and Chronic Disease
Intermittent fasting has been shown to reduce inflammation and oxidative stress, both of which are at the root of chronic illnesses of all kinds. Fasting may help to improve autoimmune diseases including Crohn’s, rheumatoid arthritis, and lupus, thanks to its inflammation-reducing and immune-regulating functions.
There are a few interesting links between intermittent fasting and reduced risk of cancer (14). During periods of fasting, our bodies focus more on repairing and rejuvenating existing cells rather than dividing and creating new ones, as cellular repair requires less energy. This is meaningful when it comes to cancer prevention, as cancer cells rely on rapid cellular division. Cancer cells also rely more on sugar for fuel than regular cells do, and therefore fasting, which results in a depletion of glucose for use as fuel, essentially starves cancer cells while continuing to provide energy for normal cells in the form of fat byproducts.
Insulin Resistance and Human Growth Hormone
Fasting is helpful for creating and maintaining overall balance, including hormonal balance. The most important example may be balancing insulin and Human Growth Hormone (HGH).
First, let’s look at insulin on its own. High insulin levels and insulin resistance can lead to a number of increasingly common chronic illnesses including type 2 diabetes, pre-diabetes, heart disease, cancer, and metabolic syndrome. Diabetes and pre-diabetes in particular are characterized by insulin resistance, which is the essentially the desensitization of the body to insulin. This most commonly occurs when we eat in excess of what we need– especially when it comes to sugar. Fasting reduces insulin resistance and helps to normalize levels of the hormone.
So, what is HGH, and what does it have to do with insulin? HGH (Human Growth Hormone) is a hormone that is essential for muscle and bone strength, tissue and cellular repair, and metabolism. Insulin and HGH can be considered opposites in a number of ways. When insulin levels go up, HGH levels go down (15). They are also largely opposite in function: HGH works to reduce inflammation, insulin creates it; HGH works to repair tissues and cells, insulin is more interested in cellular division. The playing field for these two hormones is not level: most of the time, insulin dominates. During periods of fasting, though, insulin levels go down, and HGH production increases significantly (16). This is a win-win situation.
The insulin regulating benefits of intermittent fasting are not limited to the time we spend not eating. A regular fasting practice helps to train (or retrain) the body to respond better to and make better use of insulin even when we are eating.
Intermittent Fasting and Healthy Weight Loss
Weight loss is among the most celebrated benefits of intermittent fasting, especially among those who have tried a number of different things without success. Although you may end up naturally consuming fewer calories overall when practicing a regular fasting routine, this is not the primary reason for its effectiveness when it comes to weight loss. Fasting lowers insulin levels and reduces insulin resistance (which is important for effective weight loss), boosts our metabolism, and allows our bodies to begin to burn fat for fuel. There are a number of other benefits to using fat (instead of sugar) for energy, which are explained below.
Understanding Ketones and the Benefits of Using Fat As Fuel
Most of the time, we rely on glucose, which is easily accessible, for energy. When we fast for extended periods of time, though, we eventually run out of glucose and have to find an alternative energy source. When this happens, we begin to break down fat for fuel. The byproducts of fat that we end up using for energy, called ketones, have been found to have a number of benefits for longevity, chronic disease prevention, metabolism, and cognitive function. Ketones are also much more efficient source of fuel, and they produce less inflammatory waste than glucose does.
Researchers have found that consistent periods of intermittent fasting can actually help to train the body to use ketones for energy more often even when glucose is available.
How To Implement an Intermittent Fasting Routine
There are a number of different methods and schedules out there when it comes to intermittent fasting. One of the most popular and easiest to implement is known as the 16/8 method (fasting for 16 hours, and eating all meals within an 8 hour window). For most people, this is most easily accomplished by foregoing breakfast and foregoing snacks after dinner. For example, you might finish eating by 8 PM, and not eat again until noon the next day. You may also choose to eat an earlier dinner– for example, finishing your meal by 6 PM– so that you can enjoy a late breakfast at 10 AM the next day.
If the thought of skipping or delaying breakfast is terrifying to you, start small. You might want to begin with a consistent 12 hour fast– between 8 PM and 8 AM, for example– to start getting yourself adjusted. A 12 hour fast is not quite long enough to achieve all of the cellular repair benefits of fasting or to begin to use ketones for energy, but it will allow for complete digestion, and it’s a good starting point.
You may also want to start out by practicing this type of intermittent fasting routine 2 or 3 times a week rather than every day. It can take some time to begin to see benefits, and you want to make sure that the routine you choose is manageable enough that you will be able to stick with it. You can always work your way up to longer fasts over time. Some people feel great when they do one 24 hour fast once or twice a week, and a number of the studies on fasting for chronic disease have been done with 24 hour fasts. It is not recommended to jump into this, though.
Before beginning to fast, it’s a good idea to cut back on sugar, starches, and refined carbohydrates. Fasting will be less of a shock to your system the more balanced your blood sugar is, and reducing intake of sugars and starches helps with this (among other things). Increasing consumption of healthy fats like avocados and olive oil both before and during fasting is also important for this reason, as well as to help the body adapt to the use of fat for fuel.
Intermittent fasting offers many promising health benefits, but it does not offer us a free pass to eat whatever we want when our fast has been completed. It’s crucial to eat nutrient-rich, well-balanced meals in between periods of fasting, including lots of healthy fats, lots of vegetables, and clean protein.
Make sure to stay hydrated by drinking lots of water when fasting. It’s also important to make sure your bowels are moving regularly. Drinking enough water will help with this, and supplementing with magnesium, probiotics, and prebiotics can also help to support digestion and proper elimination.
Fasting is not recommended for those who are pregnant, breastfeeding, under 18, or underweight. It’s always best to consult with a practitioner before trying fasting, particularly if you are taking prescription medications or if you have a chronic illness. Research has been positive regarding the use of intermittent fasting for diabetes (17), but if you do have diabetes or are pre-diabetic, it’s best to speak with your practitioner first, and to approach fasting slowly and cautiously.
Final note: if intermittent fasting is a practice that you are serious about exploring, build it into your life and routine in a way that is sustainable for you. Stay consistent, and stay in tune with your body. Good luck!
For more personalized guidance, request a consultation with Dr. John Gannage, MD.
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