In recent years, you may have heard about the health benefits of intermittent fasting, or IF.
There are a few different techniques which we will explore in this article, but the idea is nothing new–– it involves refraining from eating for a certain period of time. This practice has also historically been incorporated into spiritual traditions from various world religions, such as Hinduism, Christianity, Islam and Judaism.
This new form of fasting, however, is a little different. It’s not associated with any particular belief system, but it is validated by several key scientific developments, as well as supporters who proclaim the health benefits of intermittent fasting.
Whether you’re trying to lose weight, enhance longevity, balance your hormones, or reduce your chances of developing certain diseases, some experts are pointing to intermittent fasting as a simple, affordable way to allow the body to reset itself between meals.
While the science is still unfolding, what follows is a breakdown of the basics of intermittent fasting ( IF), including leading research, how it works, and the reported health benefits of this practice.
The Argument for Intermittent Fasting
Many proponents of intermittent fasting argue that evolutionarily, humans have not had access to 3 meals per day, every day (nor have they been able to snack throughout the day). In fact, many people periodically went for hours, days, or even weeks with little access to food, which may have influenced the way our bodies are designed to process food today.
Nowadays, our eating window is longer than ever. Modern technologies like electricity and the internet keep us awake later, extending the period of time in which we consume our food. This protracted consumption time disrupts our circadian rhythm and contributes to many imbalances, including obesity.
Additionally, our sedentary lifestyles make us less likely to burn the amount of calories we consume each day, leading to possible weight gain and health issues.
Finally, the quality of our food has been compromised. Processed foods and empty carbohydrates dominate the standard American diet, which are known to increase rates of obesity, diabetes and more.
Collectively, these factors have contributed to the discomfort and disease that many modern people experience. So for many, intermittent fasting can serve as a means of reinstating balance and order in our otherwise unregulated eating patterns.
How Intermittent Fasting Works
While there are a few different styles of intermittent fasting, the goal is the same: refrain from consuming food for a period of time, in order to allow the body to enter into a “fasting” mode so it can burn fat and trigger cellular rejuvenation.
To better understand intermittent fasting, we must first understand two key concepts: the role that insulin plays in the body; and a process called autophagy.
In 2017, Dr. Jason Fung published The Obesity Code, which was one of the first books to really make a case for intermittent fasting. In this comprehensive review of modern research, Dr. Fung challenges us to rethink weight gain and weight loss by highlighting the hormone insulin, and insulin resistance, as key factors in our current obesity epidemic.
Insulin is a hormone that pushes glucose (food energy) into our cells. When our cells have enough or too much insulin, we can become “insulin resistant,” meaning glucose stays outside of our cells. This resistance triggers the production of even more insulin, which can lead to diseases like obesity. So the way to break out of the cycle of insulin resistance, he argues, is to give the body a chance to rest from insulin production.
For those who aren’t dealing with obesity, similar principles still apply. As long as we don’t snack between meals, our insulin levels naturally go down, and then our fat cells can release their stored glucose as energy. If we let our insulin levels go down far enough for a long enough period of time, we’ll begin to burn off fat. This is one of the primary reasons why people are attracted to intermittent fasting.
Recently, scientists have learned more about a “housekeeping” process that happens in our body, called autophagy (in Greek, “auto” means self, and “phagein” means to eat). This is essentially our body’s way of eliminating old, dysfunctional cells and producing new ones, which, in the process, may be able to help flush out viruses, regulate inflammation, and bolster the immune system.
Autophagy is a natural part of our homeostasis, but its rate can be increased or decreased due to factors such as diet and caloric intake. When people are on a calorie restricted diet like intermittent fasting, evidence suggests an increase, or up-regulation of autophagy in the body.
However, when autophagy is disrupted, it may increase aging and diseases such as Parkinson’s, type II diabetes, and even cancer.
Types of Intermittent Fasting
As mentioned earlier, fasting in some form, is one of the oldest dietary habits known to man. Major religions like Hinduism, Islam, Judaism and Christianity all ritualize fasting, though usually in the context of spiritual teachings. However, deeper research has discovered the explicit and inherent physical benefits of these traditions.
In recent years, intermittent fasting has been popularized through publications and documentaries such as The 5:2 Diet, Eat Fast, Live Longer, The Fast Diet, and The Obesity Code, mentioned above.
Some common forms of intermittent fasting include:
Take 1-2 days out of the week to eat 25% of your normal caloric intake, while eating normally the rest of the days.
Only eat food for 4-6 hours per day, and give your body the remaining hours of the day to rest.
Often accompanied by plenty of calorie-free fluids, this type of fast lasts longer (1-3 days), and is a more extreme adjustment for the body.
Many cultures have practices of periodically “cleansing” the body by only eating a very simple food (like the Kitchari cleanse in Ayurveda, for instance) for an extended period of time (3 days to 1 week).
Regardless of the type of intermittent fasting, the principles remain the same. The point is to build in periods where no food is eaten in order to give your body ample time to use up excess energy, rest, and rejuvenate.
Health Benefits of Intermittent Fasting
While many choose intermittent fasting for weight loss reasons, there are a few added benefits involved with this practice. Below are the top 3 health benefits of intermittent fasting, as evidenced through scientific research thus-far.
1. Weight Loss
At this point, there is sound scientific evidence suggesting that, “circadian rhythm fasting, when combined with a healthy diet and lifestyle, can be a particularly effective approach to weight loss, especially for people at risk for diabetes.” (Harvard Health Publishing, 2018).
However, in many trials, anywhere from 25%-60% of the people dropped out of the diet.
So although preliminary studies suggest that intermittent fasting may help some people with weight loss, they do not necessarily demonstrate greater effectiveness than other low calorie diets.
2. Cellular Rejuvenation
Again, this is where the process of autophagy comes into play. We now know that the body periodically undergoes this self-cleaning process which expels old cells, viruses, and more and regenerates new cells. This process rapidly provides the fuel for the building blocks of regeneration, and Intermittent fasting appears to be a simple and safe way to stimulate this natural bodily response.
3. Lowered Risk of Breast Cancer, Diabetes & Cardiovascular Disease
Again, the process of autophagy is believed to reduce inflammation in the body and to boost the immune system, which are key factors in disease prevention. A 2011 study examined the health effects of intermittent calorie restriction in 107 overweight, premenopausal women over a period of 8 months. In addition to tracking weight loss, scientists measured biomarkers for breast cancer, diabetes & cardiovascular disease. At the end of 8 months, the group of women who were on intermittent fasting experienced significant reductions in the markers for these diseases.
Health Risks of Intermittent Fasting
If you’re considering experimenting with intermittent fasting, there are a few things you need to know.
First, you should NOT try intermittent fasting without consulting your doctor if you are any of the following :
- Under 17
- Over 70
- Suffering from heart, kidney or adrenal issues
- Someone who has low BMI (Body Mass Index)
Though not a risk, it is also important to know that we do not have sufficient scientific evidence on the health benefits of IF, because it can be difficult for participants to stick to, long-term. If you are someone who feels like they need to snack between meals, or cannot restrict their eating to a smaller time frame during the day, then you might not be a good candidate for intermittent fasting.
Finally, comprehensive science suggests that intermittent fasting will be even more effective when combined with a healthy, whole-foods diet rich in plants and few animal products. So, if you are considering experimenting with intermittent fasting, you may first want to be sure you are eating a healthy, balanced, whole-foods diet.
Intermittent Fasting: In Conclusion
While intermittent fasting may be a new trend for many, its fundamental properties are ancient in origin, and reintroducing them into our modern lives may unlock many beneficial biological functions.
The truth is, there are many factors that contribute to modern chronic health issues–– so a multitude of strategies are required to provide relief and optimal wellness. Commonly, we’ve pointed to calories and exercise as primary factors in weight loss, health and wellness. With new research emerging around circadian rhythms, autophagy, and more, we have greater insight into the importance of when we eat, rather than just what we eat.
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