When it comes to using energy for everyday optimal functioning, the body can either be in fed state (during which insulin levels are elevated and glucose is the energy source) or fasted state (during which uses ketones and fatty acids as energy source and the level of insulin is lowered).
Since we are not eating food all the time, our body has developed systems for storing energy, so that we can use it when food is not available. A few hours after our last meal (between 8-12h), the levels of insulin start lowering because there is no more glucose floating in the blood to be used as source of energy for our cells. When the liver receives the signal that the insulin levels are low, it starts producing another hormone called glucagon. Increased levels of glucagon tells the body to start mobilizing fat for energy. Once that happens our body enters in fasting state (which the followers of the ketogenic diet call state of ketosis).
Throughout history people fasted for many different reasons. Going back hundreds of years, people were not always consuming 3 meals per day, plus snacking in-between. There were times when food was scarce and they had to spend many hours, even days without food. Because of this our bodies have developed mechanism to deal with these periods of fame. Nowadays, some people fast out of religious reasons, and others for weight-loss, enhancing their mental focus and improving their health. One of the most commonly practiced fasting methods lately is intermittent fasting (IF).
WHAT IS INTERMITTENT FASTING?
Intermittent fasting is a process of willingly cycling periods of eating and not-eating. It refers to periods of not consuming any food and calories for extended period of time. There are a few different intermittent fasting approaches, like:
- The 5:2 approach – According to this method you can eat normally 5 days a week, while fasting 2 days. During the 2 fasting days you can still eat, consuming around 500-600 calories;
- Alternate-day Fasting – Is an approach where you alternate between not eating at all (or consuming up to 500 calories) one day and eating without restriction the next day;
- Warrior Diet – This diet follows 20h fast with consuming one large meal at night;
- 16:8 Method – This is the most popular IF approach, which I practice most of the time, where you consume food throughout 8h of the day, and fast during the rest 16h.
WHAT CAN YOU EAT WHILE DOING IF?
There is no strict rule when it comes to what type and how much food one can consume during an IF. However, my recommendation is to focus on eating whole foods, including variety of vegetables and fruits, and stick to a healthy, balanced meal plan. Also, make sure that throughout the day you are drinking plenty of water and stay hydrated.
Additionally, during your fasting period you can consume water, tea, bone broth, black coffee, bulletproof coffee, vitamins, and minerals.
HEALTH BENEFITS OF INTERMITTENT FASTING
“I fast for greater physical and mental efficiency” – Plato
Today, majority of people turn to IF for weight loss purposes. The way that IF helps with weight loss is by flipping the metabolic switch. Metabolic switch is a natural process which happens in our body when the glycogen levels in the liver and muscles are depleted and the body uses fat cells and ketones as energy source. As result of flipping the metabolic switch, our body goes from fat storage mode to using fat as energy.
Another process induced by IT which impacts the majority of its health benefits is called autophagy. The word itself comes from the two Greek words “auto” (meaning “self”) and “phagy” (meaning “eat”), which literally refers to “self-eating.” While this may sound a bit scary, our bodies eating themselves, autophagy is highly beneficial for our health.
During the process of autophagy (which optimally starts after 12h of fasting), the body recycles waste products from our cells, and removes toxins and dysfunctional cells. This leaves space for building new, healthy cells and restoring their optimal function, which makes the cells more resilient and increases their longevity. To get most out of the process of autophagy, many experts suggest fasting between 24-72 hours.
Here are the main health benefits of IF:
- Improved brain health¹
- Reducing insulin resistance and managing diabetes¹
- Improving immune system
- Improved gut health¹
- Slowing down cancer¹
- Making cells more resilient and improving their longevity¹
In addition to the physical benefits, IF also benefits us psychologically and mentally. It gives us the opportunity to overcome the fear of hunger, build discipline and practice self-control. Pushing through the discomfort of hunger can give you clarity and help you redefine your relationship with food.
WHO IS INTERMITTENT FASTING NOT FOR?
Although we just saw that IF has many health benefits, there are people with some conditions for whom IF is not recommended. This including people with type 1 diabetes, eating disorders, pregnant and breastfeeding women. Before you try IF please consult with your physician.
Additionally, if you experience any of the following signs while doing IF, you might consider calling it quits before it becomes unsafe or unhealthy for you:
- Becoming to get obsessively worry about what to eat next (it’s a disorder called orthorexia);
- Experience disruptions in your sleep;
- You have difficulty staying focused, feel fatigued or dizzy;
- Experience hair loss and irregular periods;
- Constantly feel “hangry.”
HOW TO INTERMITTENT FAST
If you are considering trying IF, my recommendation is to have your last meal the previous day as early as possible, or at least 2-3h before you go to bed. (I usually have my last meal around 6 pm, no later than 7 pm.) This way out of the 12-16h of fasting, you’ll spend 8h of sleeping. To boost your fasting state, you can consider eating keto dinner and limiting carb consumption before you go to bed. (Also, here is an app I use to track my fed/fasting periods: Life app)
In case you start feeling “hangry” in the morning, drink a few glasses of water, cup of black coffee or tea (without adding any sugar or milk because they will terminate your fasting state). A good way to overcome your hunger is making your coffee/tea bulletproof by adding grass-fed butter or coconut oil/MCT-oil (or both), or buy Bulletproof Coffee from a store near you. This will satisfy your hunger by providing you with healthy fat for energy, while keeping you in fasted state.
When it comes to IF there is no universal practice that fits all people. Take some time to experiment and try different types of IF, see how it feels and which one works best for you. Bottom line, when it comes to nutrition, the most important thing is to adhere to a meal plan that works best for you.
For those of you who would like to learn more about intermittent fasting, here are a few books which I found helpful: The Complete Guide to Fasting, Delay, Don’t Deny, Intermittent Fasting for Beginners, Eat Stop Eat.
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