Fasting has long been practiced in many human societies, and by many world religions. In Hinduism, it’s common to fast on Ekadashi, the 11th lunar day of each of the two lunar phases in a Vedic calendar month. Followers of Islam fast from dawn to sunset during Ramadan. Christians observe Lent, where followers don’t eat meat during the 40 days before Easter. Likewise, Buddhism, Jainism, Sikhism, Taoism, and Judaism have also followed fasting practices. In the past, being able to acquire plentiful or even substantial quantities of food was a luxury for many, and often not easily affordable. When it came to eating, most people had to stick to the basics. Certain food items were available only during festive seasons, and so, fasting inadvertently kept our ancestors healthy and disciplined in accordance with that which was prescribed by their religions.

So, what is intermittent fasting? How is it different from the more historically familiar idea of fasting in general? Technically, the two are not so different, one just happens to have a fancier name. So, let’s explore these terms in-depth!

Intermittent fasting involves two distinct time periods: one in which food is consumed (the eating window), the other in which nothing is consumed (the fasting window). Say, for example, you ate breakfast at 10 A.M. and dinner in the evening at around 7 P.M. That would be your eating window. Your fasting window opens after you finish eating your dinner by 8 P.M and stop eating until the next day. You’re in a fasted state until you have your next meal, whether it’s breakfast or lunch.

Funnily enough, some of us already practice this habit daily, without being aware of it! Some researchers posit that, ideally, we would all fast from dinner until breakfast, or perhaps even lunch. This is because, when we enter into a fasted state, the glucose – or carbohydrate stores –  in our bodies start to break down, so that they can be used for energy. After a period of time, once these glucose levels start to become depleted, the body automatically switches to burning stored fats from our body instead. At this point, fatty acids called ketones are released into the bloodstream, which are beneficial to the body, as they provide our brains and bodies with a more stable source of energy, and have neuroprotective effects. So in many ways, intermittent fasting can truly help us tackle obesity and other health conditions, as not only is excess fat within the body more likely to be burned as fuel, but we are also enhancing the health of our brains! We’ll explore more about these and other effects of intermittent fasting a little later, but for now let’s explore some approaches you could take when embarking on a journey like this.

Different Types of Intermittent Fasting

One approach to intermittent fasting is the “16:8” approach, which dictates that we are in a fasted state for 16 hours and can then eat within a period of 8 hours. Sound difficult? Let’s break this approach down a little more to take a closer look! If we eat dinner at 7 P.M. and then refrain from eating anything else until lunch, or a late breakfast, at say 11 A.M. The next day, we’d already be following the 16:8 approach to intermittent fasting.

Likewise, if we were to have dinner at 7 P.M. and lunch the following day only at 1 P.M. (i.e. skipping breakfast), we’d be adopting an “18:6” approach to intermittent fasting. In stretching this process out further still by having dinner at 7 P.M. and lunch the following day only at around 3 P.M., we’d be adopting a “20:4” approach. The number on the left for each of the intermittent fasting protocols we’ve described (i.e. 16:8, 18:6, 20:4) denotes the number of hours spent in the fasted state, with the number on the right representing the number of hours spent in a fed state. As you can see in the example above, skipping breakfast isn’t always necessary, but it’s an option. Intermittent fasting can also be practiced if we eat breakfast and lunch and then skip dinner, or have breakfast and dinner and skip lunch. There’s room to play around here. It all depends on your schedule! We can begin intermittent fasting at the time that best suits us. The main factor here is the number of hours between the stages of fasting and feeding. 

There are other approaches to intermittent fasting, such as the “5:2” approach, and Alternate Day Fasting (ADF). Followers of  the 5:2 approach eat in a typical manner over the course of five days, then endeavor to eat only 500 to 600 calories per day for the remaining two days of the week. The two fasting days can be consecutive or not. For example, one could consume 500 calories on Monday, eat regularly on Tuesday, return to eating 500 calories on Wednesday, and then resume regular calorie consumption again for the rest of the week.

Alternatively, with ADF, the approach is as follows: we could, for example, eat regularly on a Monday, fast on Tuesday, eat regularly on Wednesday, fast on Thursday, and so on. It’s important to consider that the fasting days have to be non-consecutive. It can be a daunting task if we’re trying it out for the very first time, but take it from those who have been fasting for longer periods, we can all reap the benefits of intermittent fasting to some degree! It’s a matter of allowing the body enough time to adjust itself to the process.

Fasting in general has many metabolic benefits. Before you decide on the approach that suits you best, always consult with a medical practitioner or nutritionist to make sure you’re following the safest and healthiest approach for you.

Calorie Restriction vs Intermittent Fasting

Some people may think that intermittent fasting is the same as restricting our daily calorie intake, but this is not the case. In adopting an intermittent fasting regime, we can eat until our stomach feels full. Indeed, with the majority of intermittent fasting protocols, there are few to no restrictions on how many calories are consumed per meal. Conversely, in the case of calorie-restricted meals and protocols, the central aim is to purposefully consume fewer calories. In other words, while the concept of intermittent fasting focuses on tweaking when you eat, calorie restriction focuses on reducing the quantities of what you eat. As such, intermittent fasting has the effect of making us more attentive to the lengths of time we’re leaving between our meals, rather than our final daily calorie intake.

A 2017 study published in the Journal of Nutrition, Health and Aging sheds light on this topic. Two groups of individuals were assigned to either an intermittent fasting regime (i.e. without caloric restriction) or a calorie-restriction regime over a period of two years. Following this time period, results showed that the participants who followed the intermittent fasting protocol without calorie restriction exhibited better health parameters than those who consumed fewer calories. 

What Happens Inside Our Bodies During Intermittent Fasting?

In general, the food we eat is largely broken down into glucose and used as energy to fuel our bodies and carry out our daily activities. If calories aren’t quickly metabolized in this way for energy, the body may choose to store them as fat for future use.

This fat that will be used for future energy is stored in our body’s fat tissues in the form of triglycerides. When the fasting window opens, these triglycerides are converted into their smaller building blocks, called fatty acids and glycerol. Now that they are broken down, these fatty acids and glycerol molecules can be used as essential sources of not only energy, but also of fat-soluble vitamins. At this point in the process, our liver chimes in and comes into its own. Indeed, our livers play the vital function of converting fatty acids into ketones, which can then serve as fuel for many tissues, especially the brain, during our fasting period.

There are fewer ketones in the body when we’re in the fed state, but there’s a considerable spike in the ketones when the fasting state starts. Within 8 to 12 hours of fasting, the ketones reach 0.2 to 0.5 mm, and they almost double by the end of 48 hours of fasting. These ketones play a vital role in healthy cell and organ function in our bodies. Ketones influence the expression and activity of many proteins and molecules, affecting health and aging. Pretty interesting, right?

Now Let’s Talk About The Six Holistic Benefits of Intermittent Fasting!

  1. Helping to reverse Type 2 diabetes. Intermittent fasting can be a powerful way to help in the reversal of Type 2 diabetes. Diabetes creates insulin resistance in the body, and the practice of intermittent fasting helps to reduce insulin resistance, thereby also helping to reduce one’s levels of fasting glucose and fasting insulin.
  1. Weight loss. As the body enters into a fasted state, depleting its glucose levels, it switches to the body’s fat reserve, helping the body lose weight that has been stored in the form of excess fat. Intermittent fasting can produce clinically significant weight loss, as well as improve metabolic health in individuals with obesity. An analysis by researchers at the University of Illinois showed how all forms of fasting reviewed in this meta-analysis (i.e. ADF, the 5:2 diet and time-restricted eating) were seen to produce mild to moderate weight loss. In some studies within the review, participants who were overweight or obese lost an average of 3% of their body weight after following a time-restricted eating protocol, regardless of the time of the eating window. Some studies in the review also showed that ADF resulted in a loss of 3-8% of participants’ body weight over three to eight weeks, with weight loss results for ADF strategies seeming to be at their peak effectiveness at the 12 week juncture.
  1. Anti-aging and longevity. When we employ intermittent fasting strategies, our overall insulin sensitivity is improved. As we described, when stores of glucose are running low in our fasted state, the body switches to fat-burning mode, as it still needs energy to keep the body functioning. In this process of using fat as fuel, levels of a chemical that we make in our bodies called human growth hormone (HGH) are significantly boosted. HGH plays a crucial role in keeping our muscle mass and bone density up to the mark, which acts to delay the aging process. HGH may also help us live a life free of many age-related complications, which in itself may ultimately increase our lifespan.
  1. Cognition and focus. Intermittent fasting has been shown to enhance cognition in multiple domains, such as for those suffering from brain disorders like Alzheimer’s disease, multiple sclerosis and epilepsy. Balance and coordination have also been seen to improve in animals on daily time-restricted feeding or alternate-day fasting regimens.    
  1. Reduced inflammation. Experiments have been conducted to show that intermittent fasting reduces the release of pro-inflammatory cells called “monocytes” in blood circulation. With some deep diving into this area, it was also discovered that, during periods of fasting, these inflammatory cells become less active, and are therefore less inflammatory than their cellular counterparts found in those in a fed state.
  1. Assists autophagy. The word autophagy comes from the Greek words auto, meaning self, and phagein, meaning to eat. In other words, to “eat the self”. This is a natural process carried out by our bodies since birth. Thousands of microscopic bodily cells die, with new ones taking their place daily. This is where the autophagy process comes in, as it serves to hinder the accumulation of toxins in cells, removes any harmful cells and recycles dead cells. Eating in a time-restricted window can speed up autophagy and rid the body of waste and toxic cells, delaying the onset of certain diseases like Alzheimer’s and Parkinson’s. Additionally, studies on rodents have shown that ADF can reduce the occurrence of spontaneous tumor formation, as well as suppress many other types of tumors, allowing them to better respond to chemotherapy and radiation.

What Can We Eat in the Fasting Window? Let’s Take a Look!

In the fasting window, we can’t consume any solid foods; this is ideally the stage of abstinence from food. Water, black coffee, and black tea are some go-to options that aren’t considered to break the fast. Bear in mind that it’s better not to consume drinks that may spike our insulin. The idea is to keep our insulin levels as low as possible for the fasting period, in order to reap the greatest benefits. Water, tea without milk or cream, and black coffee don’t contain significant calories, or anything that may induce insulin production in the body for digestive purposes. So, sipping on tea and coffee could help you deal with any hunger pangs you may experience at the beginning of the intermittent fasting regime.

Once the feeding window starts, is it okay to eat everything available to us? As far as possible, it is actually recommended to maintain a generally healthy diet during any feeding stage, as our bodies still require a large variety of nutrients and high quality food sources in order to perform well and to carry out their many tasks. As such, no – it’s not recommended to consume everything in sight once we reach the feeding window. While there’s no specifically prescribed diet that we are required to follow when experimenting with an intermittent fasting protocol, your chosen meals will depend on individual choice, taste, and perhaps even product availability in your region. As much as possible, we can try to eat a variety of healthy, nutritious foods that are delicious and help our bodies and brains to function well.

Try to avoid eating highly saturated, sugary, or baked items in the feeding window. These foods may not positively affect our bodies, or give the full benefits you’re looking for. In the first weeks of experimenting with intermittent fasting, it’s possible that we may feel dizzy, and experience headaches, irritability, etc. though these symptoms improve over time. In the early phase, for about two to three weeks, we may eat more than usual during the feeding window, but this is only natural. Once our bodies adjust to this novel regime, the hunger pangs will tend to fade, and we may start to derive greater enjoyment from the process when we start to see results. Indeed, researchers publishing in the journal Cell Metabolism noted an overall improvement in health for those following an intermittent fasting protocol, irrespective of what is eaten during the feeding window. The bottom line here is that eating healthy food is good for us, our environment, and our planet, wouldn’t you agree?

The 21st century has brought a lot of technological innovations, which certainly help with our creativity, as well as our food availability and accessibility. We’ve been blessed by an abundance of choice. We have far more milk and meat alternatives and types of bread and grains than we ever previously had! Today, we’re able to explore and enjoy delicacies from every culture in the world, often at the click of a button. However, our immunity is at its lowest ever ebb. Many of us are grappling with lifestyle-based diseases unknown to our ancestors. Is there a light at the end of the tunnel? Yes, definitely! Intermittent fasting can help us lead the life we are all striving for.

Is Intermittent Fasting Restricted to a Specific Group of People?

It’s very important that people with certain medical conditions consult with their doctors before starting to explore intermittent fasting. For example, pregnant women, breastfeeding mothers, or women trying to conceive are strongly advised to seek professional advice from health practitioners before embarking on a journey such as this. Underweight individuals, children under 18 years of age, and people who have a history of, or are in the process of dealing with, an eating disorder are not recommended to try this particular protocol. Furthermore, people with diabetes and blood pressure problems may not be in the position to take this up independently without professional guidance.

Now that you know just how many holistic health doors the practice of intermittent fasting can help you to unlock, you can choose which approach you find most convenient for you – i.e. one that fits your health goals, and that matches with your personal schedule. Whether you’re opting to try out the OMAD approach, or the 16:8, it’s always advisable that you consult a health professional, such as a nutritionist, beforehand in order to ensure that intermittent fasting is a safe and beneficial practice for you.