Why I Intermittent Fast
I have seen significant improvements in my health since I implemented IF (intermittent fasting) 1.5 years ago. I practice a 16 hour fast with an 8 hour feeding window 6 days a week. Once a week I practice a 20-24 hour fast. I have seen significant changes in my mental health and ability to manage my hunger. Additionally I have found the practice of IF to make my life easier. By not having to plan and eat breakfast, I have more time available in the morning.
In this blog post, I will go over what IF is and the potential reasons why I am experiencing these benefits.
What is fasting?
Fasting is the abstention from food. We all fast overnight, between 6-8 hours. That’s why we call breakfast break-fast. Breakfast literally means to break the fast. Voluntary abstinence from food is also fasting. After an overnight fast, we can choose to continue the fast for an hour, 5 hours, 24 hours, etc. If one has their last meal at 7pm and does not eat again until 11am the next day, that person will have fasted for 16 hours.
History behind fasting
As humans, we have practiced fasting for millions of years. Three meals a day with snacks was not an option for most people until the industrial revolution. For most of human existence, our ancestors experienced feast and famine. Eating all the time was not an option. We are adapted for two states- the fed & fasted states. Permanently staying in the fed state is bad. Permanently staying in the fasted state is also bad.
Most major religions have practiced fasting. Religions that practice fasting perceive it as good for the human body and spirit. They do not perceive it as harmful.
Muslims do not consume food or drink between sunrise and sunset for a month during Ramadan. Some Greek Orthodox Christians follow various fasts on 180-200 days of the year. Buddhist monks abstain from eating between noon to the next morning.
“The best of all medicine is resting and fasting”
Benjamin Franklin
Fasting has also been used as a heath remedy. The father of modern medicine, Hippocrates, prescribed his obese patients to fast 24 hours a day. Plutarch, ancient Greek writer, is quoted as saying “Instead of using medicine, better fast today.” Ancient Greeks also utilized fasting as a tool to improve mental clarity. Both Plato and Socrates fasted for 7-10 days to gain physical and mental efficiency. Pythagoras fasted 40 days before his exam in Alexandria.
“To eat when you are sick, is to feed your illness”
Plutarch
Less Hungry & Less moody
Personally, when I skip a meal (like breakfast) I do not eat double the amount for lunch. In fact, I eat just a little more than I would if I did have breakfast. So overall, I am consuming less food by waiting until lunch to eat. Also the more I IF, the less often I feel hunger spikes throughout the day. This stable source of energy also keeps my mind working well.
This is probably due to the fact that IF helps with metabolic flexibility. Metabolic flexibility is the ability to efficiently switch between burning fats and carbs as a source of fuel. When we are metabolic flexible, we are less dependent on carbs for energy. This is because after 12 hours of not eating, our glycogen stores (where carbs are stored in the body) start to run out. Our body then starts to burn the fat on our body as a source of fuel. The more we allow our bodies to tap into our stored fat, the better we are at burning it.
At first, one may feel tired and hungry when implementing IF. This is because that person is not accustomed to utilizing fat as the main source of fuel. They have primarily burned carbs as a source of energy. After a period of time, it becomes easier to fast as the body becomes more accustomed to burning fat as a source of fuel. By being more metabolically flexible, one is less dependent on carbs for energy. This is because our body can easily utilize and burn fat stored on the body.
“Glycogen is like your wallet. Money goes in and out constantly. The wallet is easily accessible, but can only hold a limited amount of money. Fat, however, is like the money in your bank account. It is harder to access that money, but there is an unlimited storage space for energy there in your account. Like the wallet, glycogen is quickly able to provide glucose to the body. However, the supply of glycogen is limited. Like the bank account, fat stores contain an unlimited amount of energy, but they are harder to access.”
Jason Fung, The Obesity Code
My improved mental health may be due to the fact that my blood sugars are stable when I fast. When I am fasting, my primary source of energy is coming from the fat on my body. My body creates a steady source of glucose in the liver via gluconeogensis. When one consumes carbs multiple times a day, one is primarily using carbs as a source of fuel. They are not used to burning the fat on their body as a source of fuel. Consuming carbs multiple times a day will cause highs and lows in blood sugar. Highs and lows in blood sugar may result in unfavorable changes in mental health. When blood sugars crash down, 3-4 hours after eating, one may feel shaky, irritable, and “hangry”. Do you ever experience an intense desire to consume a bagel, oatmeal or bread first thing in the morning? Or just 3 to 4 hours after eating? That is the product of metabolic inflexibility. The difficulty to utilize stored body fat for energy, resulting in low blood sugars. Low blood sugars create the desire to consume carbs to bring blood sugars back up.
Potential benefits of ketones on brain
When we burn fat as fuel, some of this fat converts to ketones in the liver. Ketones are an alternative fuel source for the body when glucose is in short supply. These small molecules are used as energy throughout the body, especially the brain. The brain can run on glucose or ketones for fuel.
Ketones may play a role in mental clarity and mood. A ketogenic diet can reduce seizures in epileptic children. It may also slow down the progression of Alzheimer’s disease. In fact, in Alzheimers disease, the brain loses the ability to use glucose. Some theorize that this is the result of chronically consuming a high carb diet The brain can use both ketones and glucose as a source of fuel. Ketones can serve as an alternative fuel source for Alzheimers patients.
In addition, ketones have been shown to enhance mitochondrial respiration, increase neuronal growth factors, strengthen signal between synapses, reduce brain inflammation and reduce oxidative stress. This too may be why my mental health has improved through IF.
Insulin and weight maintenance
Every time we eat, we experience a rise in insulin, a hormone produced in the pancreas. Insulin is necessary for health, but it can cause problems when elevated all the time. When insulin is elevated, we can not burn the fat that is on our bodies. Insulin lowers significantly during IF, making it easy for our bodies to burn stored body fat.
Additionally there is an inverse correlation between insulin and memory. The lower the insulin level, the more memory improves.
When insulin goes down, counter-regulatory substances such as cortisol and norepinephrine go up. Cortisol and norepinephrine are substances that keep us awake and alert. This too may be a reason why I experience an increase in focus when I IF.
Won’t IF lower my metabolism? Will it put me into starvation mode?
In order for our body to function properly, our body is required to burn a certain amount of calories per day. This is measured through BMR (Basal Metabolic Rate). BMR includes basic body processes that we must do every day to stay alive such as breathing, brain function, heart pumping. In fact, most of the calories we burn in a day are through these basic functions, not exercise. BMR is not a fixed number. It can vary by up to 40% based on different variables.
Caloric restriction is well documented to cause a dramatic reduction in BMR. Going from 2500 calories per day to 1500 over a long stretch of time will reduce BMR by 20-30%. The body can not run on a deficit for too long. In a response to the deficit, the body will decrease energy output, decreasing BMR. This reduced metabolism makes us feel cold, tired, hungry and less energetic. Our body is conserving energy because we are providing it less energy. Calorie restriction= lower metabolism= feeling hungry all the time= eventual weight gain. This is precisely why calorie restriction is not an effective weight loss strategy.
Fasting is different from caloric restriction. Caloric restriction is the reduction of food consumed throughout the day. Fasting is the complete removal of food for a period of time. This complete removal of food actually revs up the metabolism. This is because eating nothing signals the body to start burning fat stored on the body. This makes sense from an evolutionary standpoint. Our ancestors would not be able to get their food if they were tired and sluggish all the time.
When we fast, norepinephrine shoots up, a neurotransmitter that prepares the body for action. Norepinephrine keeps us energized and alert.
Additionally, the notion that fasting decreases muscle mass is non-founded. Our bodies have evolved to primarily use stored fat as energy, not lean tissue. Fasting signals the body to excrete growth hormone secretion. This growth hormone helps preserve lean body mass.
Through an evolutionary lens, it does not make sense that our ancestors would lose muscle when deprived of food. The body would want to burn the stored fat first. That is why we have body fat — for energy storage. Body fat is there to provide energy in the event we are out of food. It does not make sense that our body would choose to burn muscle over fat in the absence of food. Our bodies are smarter than we like to give them credit for.
This has been shown in studies. During alternate-day fasting over seventy days, body weight decreased by 6%, fat decreased by 11.4% and lean mass did not change at all.
Reflection
IF has helped improve my energy levels, appetite regulation, and overall mood.
IF has improved my metabolic flexibility. I am better able to switch between burning carbs and fats as a source of fuel.
This metabolic flexibility provides me a steady source of energy through the fat on my body. By being less dependent on carbs, I do not experience the highs and lows in blood sugar. Stable blood sugar provides me with steady energy and appetite regulation.
IF also increases substances that keep me awake and alert, such as cortisol and norephinephrine. I produce ketones when I IF. These ketones may provide my brain with therapeutic benefits through inflammation reduction.
These health benefits make sense through an evolutionary standpoint. Our ancestors did not have access to food 24-7. They had periods of feast and famine.
It makes sense that our ancestors would evolve to be alert during periods of famine. They needed to be awake, alert and energized to be able to find their next meal. When we eat a lot, we feel tired and sluggish. This is because our body is focused on processing the food. Our body does not need to be alert and attentive because it has the food it needs. It is when their is an abstinence of food that the brain fires up. This concept has been understood by many important thinkers of the past. The ancient greeks are one example. They utilized fasting to improve their attention and overall health.
I encourage you to try IF if you would like to improve your mental health and/or better manage your weight. Start with a simple 12 hour fast. Once that becomes easy, increase to 13 hours, then 14 and so on and so forth. I would not recommend going over 24 hours without consulting a doctor. During a fast, make sure to drink plenty of water. Black coffee and tea may be consumed during a fast because they do not contain any calories. After a fast, eat a substantial meal that is rich in protein and fat. Listen to your body and eat until your full. Do not deprive yourself!
If you have any further questions about the practice, feel free to message me!