Fasting for mental and physical health is not a new concept. In the last few years, fasting is everywhere. And, as with many things brought over from ancient cultures, there are just as many kinds of fasts, voices and ‘experts’. This can be overwhelming for someone just starting out. So, here is my smart yet simple guide to Fasting for maximum health impact. I based this in my own practice and evidence-based science. I will explain why you should make this an essential part of your healthy-living strategy. I have also included key biohacking tips on how to easily add fasting to your daily routine for maximum health benefits.
Many cultures have been practicing fasting for hundreds of thousands of years. For example, in Muslim culture, faith-followers are encouraged to fast from sunrise to sunset for 30 consecutive days once every lunar year. During a fast, muslims don’t eat or drink anything until sundown. This is also known as a dry fast. This month of fasting is celebrated with 3 days of feast at the end. The primary objective is to practice discipline, gratitude and improve health. There is also a spiritual aspect to this period which includes reflection and those with means are obligated to share their food with the less fortunate ones.
Why fast for health?
Fasting is associated with a long list of benefits for our bodies and minds. So much of what we do on a daily basis is based on our beliefs, routines and fears around food. Besides allowing our systems to reset and reset, fasting allows us to learn to listen to bodies better at a deeper level.
If you’re concerned about fasting and not having enough energy to burn, just know this: Even when you’re at the lower end of your normal body weight, you still have about 15-25% of your body weight stored as fat. This is around 30,000 to 100,000 excess calories worth at any given time. It may not be comfortable in the beginning, but you can start slow. You’ll be surprised, how quickly your body adjusts to this new routine.
Here are some of the key benefits of fasting:
- Fasting may support sustainable weight loss. Our bodies are not made to eat as often as we do in modern times. Our hunter-gatherer ancestors spent hours each day searching for food that was not consistently available. They’d fast, and then they’d feast. These ancient humans developed a “thrifty” genotype that helped them adapt to these cycles of want and plenty. Today, we carry the same genotype. This means that the body functions at its optimum level when we are not feeding it constantly. If we feed our body constantly with 3 meals plus snacks in a day, we may get extra fat on our bodies, our insulin sensitivity may be reduced, and our body may not perform as well as it could.
- Fasting may help improve insulin sensitivity. Insulin sensitivity and Type 2 Diabetes is an invention of our modern diet. This is now one of the biggest diseases in the world. What is insulin sensitivity? After a meal, carbohydrates are broken down into glucose, an immediate source of energy. Excess glucose gets stored in the liver as glycogen or, with the help of insulin, converted into fatty acids, circulated to other parts of the body and stored as fat in adipose tissue (also known as body fat). When there is an overabundance of fatty acids, fat also builds up in the liver. If we allow enough time between meals such as during an Intermittent Fast (IF), our insulin levels eventually go down, and our cells release stored sugars and we burn off our fat. If we have too much fat stored in our cells, our cells do not allow insulin to bring in more fat, and hence insulin sensitivity decreases. This can lead to Type 2 Diabetes. Here’s a link to an article I wrote about Insulin Resistance: What You Can Do About It?
- Fasting may reduce inflammation and auto-immune diseases. It does so without affecting the immune system’s response to acute infections, according to a new study by researchers at Mount Sinai in New York and published in the journal Cell.
- Fasting improves gut health. Studies show that Intermittent Fasting can promote the growth of beneficial bacteria and decrease harmful ones in the gut.
- Fasting may increase lifespan, and promote healthy aging. In a 2017 study published in Science Translation Medicine by Dr. Valter Longo, results showed that intermittent calorie restriction is highly effective in reducing risk factors related to aging and age-related diseases such as Diabetes, high blood pressure and cardiovascular diseases.
- Fasting promotes Autophagy. Autophagy means “self-eating.” It’s a detox process your body undergoes to clean out damaged cells and regenerate new ones. This happens only in the absence of external resources aka. food. Autophagy starts at around 18-20 hour mark of IF (intermittent fasting), and maximum benefits are usually around 48-72 hours. In fact, scientists are now exploring Autophagy as a therapeutic strategy for cancer suppression. It is one of the best ways to detox and is completely free!
- Fasting improves mood, anxiety, memory, focus and overall cognitive functions. It does so by regulating inflammatory pathways in the brain. It is now being explored as a therapeutic for Alzheimers, anxiety and epilepsy among other conditions related to brain function.
The Importance of Circadian Eating
Before we dive into fasting specifics, it is important to understand how eating and circadian clock impact each other. The right way to practice intermittent fasting (and eating habits in general) is by syncing your eating times to your circadian clock. According to a study done at USC by Dr. Valter Longo, the circadian clock intimately interacts with nutrient-sensing pathways. Circadian Rhythm or Day and Night rhythm is an imprinted clock in our organs and systems and respecting it by not eating during the night mirrors this internal clock. The clock regulates critical functions such as behavior, hormone levels, sleep, body temperature and metabolism. Our wellbeing is affected when there is a temporary mismatch between our external environment and this internal biological clock, for example when we travel across timezones, or if we eat late in the night. This mismatch can lead to our inner mechanisms being thrown out of balance which can eventually lead to weight gain and disease. This discovery was awarded the Nobel Prize in Medicine in 2017.
Circadian eating balances periods of food intake with periods of no food intake. This helps the body take a break from intaking food when it should be spending it to help repair and restore during the night. If we eat late into the evening, the body then stores this food as fat. In fact, there have been numerous scientific studies such as this one that showed that by eating the exact same amount of calories earlier in the day, dieters who ate their main meal before 3 p.m. lost significantly more weight than those who ate later in the day.
Following a circadian rhythm fast, for example, you might fast by not eating between from 6pm to 8am, or 8pm (depending on what works best for you) to 8am which could help you maintain a healthy body weight. There have been many scientific breakthroughs and discoveries in the field of time restricted eating, calorie restriction, metabolism, seasonal rhythms and circadian rhythms. Read my guide to seasonal rhythms and living here.
3 Types of Fasting
Fasting is a powerful and free tool at our disposal to improve our health immediately. It does not need to be complicated. You can start simple and slow. The ultimate goal is to give your body a break, to heal and rejuvenate so it can go on to be the healthiest home for us. While there are many different types and durations of fasts, once you know the science behind it, you can experiment to see what works best for you. And, you can even change it up based on how you feel at any given time.
Fasting strategies can be simplified into 3 types.
- Intermittent fasting (12-14 hours or 5:2)
- Short-term fasting (2-3 days)
- Prolonged fasting (3+ days)
1. Intermittent Fasting (also known as Time Restricted Eating)
IF (or TRE) includes fasting from anywhere between 12-24 hours on a regular basis. This gives your body a break from digestive processes and repair itself.
If you are just starting out, or looking for a sustainable way to incorporate fasting into your routine, I recommend starting with 12-14 hour of fast. For example if you eat dinner at 6pm, then have breakfast at 8am the next day. No snacks in between. This type of fast is also a common practice among most of the centenarians and people living in the Blue Zones.
A 14-16 hour fast is a key part of my own health strategy. I find it easy to incorporate in my daily life without giving up too much. It helps me keep my glucose levels in check (Type 2 Diabetes runs in my family). In the past, when I had lyme disease, fasting improved my inflammation levels and pain considerably.
This type of Intermittent Fasting or TRE also includes other types of fasts such as alternate day fast (which is usually not recommended by most health practitioners) and 5:2, where you restrict calories to less than 500 for women and 600 for men on 2 days of the week. These are non-consecutive days. The rest of the 5 days you eat regularly. However, this particular strategy is mostly used for weight-loss and you can also achieve the same benefits with time restricted eating.
2. Short-term Fasting
Short-term fasting includes a fast for 2 or 3 days. This type of fasting is a little harder than Intermittent Fasting and is often used for help managing disease, aging and inflammation etc. The discovery of Autophagy won the Nobel Prize in Medicine in 2016. In simplest terms, autophagy is the process by which a cell consumes its debris and organelles in order to rejuvenate and clean its inside space.
3. Prolonged Fasting
This type of fasting means only consuming water for 3 or more days. The main objective for practicing prolonged fasting is to induce a faster weight loss and trigger a deeper ketosis and cellular effects such Autophagy and cellular rejuvenation, all of which support healthy aging and metabolic reset. Ketosis is a process where your body switches to burning stored fat, after it has used its stored glucose.
I’ve been practicing a 5-day fast at least once a year for healthy aging and improving physical and mental performance. Since, this type of fast can be difficult, I use Prolon® fasting mimicking diet. The ProLon Fasting Mimicking Diet® gives the benefits of a fast while providing tasty food and nourishment to help fight hunger and protect lean body mass. During this diet, you get about 800 calories on day 1, and then 500 calories during the remaining 4 days. Not a lot of food, but I still find it to be far easier than a water alone fast. Here’s a 10% discount on Prolon® Fasting Mimicking Diet through my affiliate link if you’d like to try it out.
6 Ways to use this science for better health
How can you use the latest scientific information in your daily lives to achieve maximum benefits even when you’re not fasting? This is where knowledge becomes powerful and allows us to use science to achieve focused benefits. Some may even call this biohacking.
- Avoid refined carbs and sugar. Instead, eat fruits, vegetables, beans, lentils, whole grains, lean proteins, and healthy fats (a sensible, plant-based, or plant-heavy diet).
- Let your body burn fat between meals. Avoid snacking. Snacking doesn’t allow your body to burn its stored reserves. It also taxes your digestive system by now allowing it to rest and repair.
- Build muscle tone as muscle helps burn stored glycogen. To turn your body into a fat-burning machine, you have to deplete the glycogen stored in the liver and the muscle glycogen stores. Otherwise, excess glycogen is stored as fat in the body.
- Consider a simple form of intermittent fasting. Limit the hours of the day when you eat, and for best effect, make it earlier in the day to take advantage of the circadian clock (between 7 am to 3 pm, or even 10 am to 6 pm, but definitely not in the evening before bed).
- Eat nutritionally dense foods so that your body is getting all the right nutrients it needs during the repair process. Eat lots of colorful vegetables, leafy greens and fruits such as berries.
- Stick with it. In the beginning, especially if you’re not used to it, you may be consumed with feeling hungry or thinking about food. My tip is to start with a simple 12 hour, and then increase your daily fasting window by 1 hour each week until your reach your goal (at least 14-16 hours 2-3 times a week). This is often due to the fact that our bodies are used to primarily running on glucose which is what we want to improve. Trust me, it gets easier over time and you may soon enjoy the improvement in mental clarity and physical health.
What Happens to Your Body on a Fast
Dr. Valter Longo describes the day by day impact of fasting on our bodies as follows:
Day 1: Fasting State. The body transitions into burning glucose and stored glycogen.
Day 2: Fat burning and Ketogenesis. Body continues to burn through stored glycogen in most people. Fat-burning ramps up, contributing to the initiation of ketogenesis (ketone production for fuel using stored fat). By the end of this day (48hrs), ketosis may occur.
Day 3: Autophagy. Cellular clean-up (autophagy) begins. Fat-burning and ketone production/ utilization continues and increases
Day 4: Cellular Rejuvenation. Cellular cleaning/renewal & fat-burning continues.
Day 5: Regeneration and Renewal. Stem cell-based regeneration continues for rejuvenation from within.
What to Eat When You Break Your Fast
No matter what type of fast you follow, what you eat when you open your fast is critical. It is the food that your renewed cells will be waiting for all this time. You are what you eat, after all. So, make sure to give it the highest amounts of nutrition as possible. I like to open my fast with a smoothie like this one, which has a good amount of antioxidants, healthy fats and protein. Soups are also a good option. I like to break my fast with mostly plant-based foods as animal products can be taxing on our bodies. If you choose to break your fast with solid foods, it is better to stick to lightly cooked vegetables as they are gentler on the body than raw salads.
And as always, stay away from processed food, sugar, refined carbohydrates and fried foods. These so-called ‘foods’ have no room in a healthy life anyway!
I hope this post has helped explain the science behind fasting and how you can simplify it to fit your life. Let me know if you found this useful or if you have any questions. Also, we have an amazing Private Community of women who are enthusiastic about improving their health. It’s free and we would love to have you join us here.
Note: Fasting may not be for everyone. Especially, pregnant women, people with certain medical conditions such as Type 1 Diabetes or eating disorders should not fast or should consult their doctors.