It’s an established fact that going without food is therapeutic. What you may not know is the hour-by-hour benefits of fasting. For instance, what are the hourly benefits of fasting for six hours, 16 hours, or 48 hours, in terms of its impact on blood sugar, insulin, liver glycogen, human growth hormone, fat burning, glucagon, and the magical process of autophagy? Stay with me as I break down the process.
The Process Of Fasting
Here’s a brief overview of what happens physiologically when you fast. The human body runs on energy. Energy is needed both in a fasted and non-fasted state. The body’s main energy source is glucose, which is abundant in carbohydrates. Both the liver and muscles store glucose in the form of glycogen.
This stored glucose is a secondary energy source, and is what enables you to sleep through the night without needing to eat. Approximately 1200 calories of glycogen are stored in the muscular system and liver. The liver stores simple sugars, whereas, complex carbohydrates are stored in the muscle. How much glycogen you’re able to store is in direct correlation to how much muscle mass you have.
When glycogen becomes depleted, the body transitions into a fasted state. Energy is then created via a process called gluconeogenesis, whereby energy is made using protein and fat. Since no glucose is coming in, energy must still be made, and with glycogen no longer available, fat becomes the preferred energy source. This is why weight loss is a welcomed side effect of fasting.
Over time, when fat can no longer be used, the body eventually enters starvation mode, which causes the metabolism to slow down. The body then resorts to burning muscle for fuel. This scenario typically happens after weeks of fasting. My preferred method of fasting is intermittent fasting, which is more sustainable and strategic than traditional fasting. The OMAD diet is another method of fasting where just one meal a day is eaten. Read my posts below to learn more:
[Read More: Human Growth Hormone and Intermittent Fasting]
[Read More: 7 Reasons To Consider the OMAD Diet]
Human Growth Hormone
Human growth hormone (HGH), secreted from the pituitary gland, is responsible for regulating growth and body composition, protein synthesis, fat-burning, muscle and bone growth, and fat and sugar metabolism. It regulates the growth of every cell in the body. It is the hormone associated with youth, and like other hormones, declines with age.
Low levels of human growth hormone lead to reduced muscle mass, increased body fat, reduced bone density, insulin resistance, cardiovascular problems, anxiety and depression, low-exercise tolerance, fatigue, and insomnia. Essentially, it manifests as the symptoms associated with aging. Increased levels of HGH improve body composition, stabilize mood, boost energy, and optimize immune function. HGH is the ultimate fat burner and its production increases during fasting.
Ketosis is a metabolic state characterized by high levels of ketones in the blood. Ketones are made in the liver and are produced when insulin levels are low, and when glucose can’t be used for energy. Ketosis can be achieved by restricting carbohydrates to under 50 grams a day or by fasting. In this state, energy is created by burning stored body fat, rather than burning glucose for fuel.
With carbohydrates so plentiful, most people rarely enter ketosis, an adaptive metabolic pathway used in times of scarcity when sources of glucose aren’t available. Ketosis is a normal state of metabolism with ketones providing a reliable alternate energy source.
There are many variations of the ketogenic diet, just as there are numerous ways to intermittent fast. The benefits of ketosis include hormone and blood sugar regulation, increased fat-burning, appetite suppression, better oxygen utilization, the preservation of muscle glycogen, increased mental focus, and better physical performance.
Authophagy is a hot topic. In fact, the Nobel Prize in medicine was awarded for work on autophagy, which means “self-eating” or “self-consuming.” And that’s exactly what autophagy does, it recycles old, damaged, and diseased cellular components so they can be reused. Worn out cells need to be replaced for systems in the body to function optimally. This recycling process is stimulated by fasting as the body cannot “self-eat” when food is coming in.
Benefits of autophagy include: increased insulin sensitivity, eradication of pathogens, increased detoxification, reduction in progression of degenerative diseases, such as Alzheimer’s, Parkinsons, and even cancer, due to its favorable effect on tumor progression. Autophagy retards aging, reduces inflammation, boosts stem cell production, balances hormones, increases growth hormone, and improves immune function. Notably, brain tumors have been shown to regress from autophagy.
Autophagy is stimulated by fasting for at least 16 to 20 hours. For the process to be activated, glycogen stores need to be depleted and ketosis induced. All excess calories must be burned before autophagy kicks in. The number of calories previously consumed will be a determining factor as to when the process begins. Exercise, and movement of all types, accelerates glycogen depletion as will implementing a ketogenic diet.
Glucagon is a fat-burning hormone secreted by the pancreas that opposes the effects of insulin. Insulin is secreted by the beta cells within the gland, whereas, glucagon is released from the alpha cells.
The actions of insulin and glucagon work in tandem to keep blood sugar levels stable. The role of glucagon is to raise the concentration of fatty acids and glucose in the blood when insulin levels are low. Elevated insulin levels, on the other hand, prevent the release of fat.
When glucagon is elevated, glycogen in the liver is mobilized. Glucagon induces lipolysis, the mobilization and breakdown of stored energy, when levels of insulin are low. It increases the expenditure of energy, and is raised during times of stress, such as fasting.
The Hourly Benefits Of Fasting
Here are some of the tremendous benefits of fasting that are broken down into specific time increments:
4 to 6 Hours
At the four-hour mark, all food has left the stomach. Blood sugar is decreasing, as well as insulin, which is no longer produced in the absence of glucose. If you consistently spaced your meals every four hours, instead of eating every two like many people do, you would regulate your hormones and body weight.
After eight hours of fasting, glycogen reserves are depleted. Gluconeogenesis is initiated as the body enters a fasted state. Since glucose is no longer available, the liver converts protein and fat into energy. Calorie-burning is accelerated, the basal metabolic rate slows, and the body becomes more efficient at using available energy. Due to this reduction in metabolic rate, blood pressure and heart rate both decrease.
The body enters a healing phase after 12 hours without food. The digestive system begins to rest as there are no calories to burn. Levels of human growth hormone ramp up, and glucagon is secreted from the pancreas to keep blood sugar levels within the normal range.
At this point in the fasted state, the body begins to convert fat into glucose for energy. Human growth hormone continues to rise significantly as fat-burning continues. The most incredible benefit of fasting is the cellular clean-up process of autophagy, which is mildly induced around the 16-hour mark. This is when things start to get good.
Precisely when autophagy is activated will depend on several factors, such as, how many carbs and how much protein were eaten at the last meal, if exercise was part of the picture, and if any fruit was consumed. Fruit contains fructose which replenishes glycogen stores.
|4 – 6 hours||Reductions in blood sugar and insulin|
|8 hours||Glycogen reserves are depleted, gluconeogenesis is initiated, the liver converts protein and fat into energy
Calorie burning is accelerated, basal metabolic rate slows, blood pressure and heart rate both decrease
|12 hours||A healing phase is initiated, the digestive system begins to rest, levels of HGH ramp up
Glucagon is secreted from the pancreas to keep blood sugar levels within normal range
|14 – 18 hours||Fat is converted into glucose for energy, HGH continues to rise as fat-burning continues
The cellular clean-up process of autophagy is induced around the 16-hour mark
|24 hours||Autophagy takes off, toxin-elimination ramps up, fat-burning is in full swing as HGH increases
Insulin decreases, ketones are released, lipolysis is induced
|36 hours||Autophagy skyrockets, HGH production increases, fat-burning and toxin-elimination continue
Insulin continues to drop, while lipolysis increases
|48 hours||Autophagy increases unabated (up to 30%), the immune system begins to repair and regenerate
The inflammatory process is reduced, lipolysis is maintained, cellular toxins are released
|72 hours||Autophagy continues to work its magic and accelerates up to five fold due to calorie-restriction
and reduced insulin levels
The incredible process of autophagy really takes off at the 24-hour mark. Toxin-elimination also ramps up. Fat-burning is in full swing thanks to the rise in HGH and the decrease in insulin. Ketones, an efficient source of energy from fat, are released. The more insulin sensitive a person is, the faster lipolysis will be induced, which underscores how critical exercise and its insulin-lowering effects are.
The cellular clean-up, repair, and renewal process of autophagy continues to skyrocket. HGH production, fat-burning and toxin-elimination continues due to the drop in insulin and boost in lipolyis. Reducing levels of insulin is very significant, but so is the amount of time that levels remain low. This is why longer fasts yield such amazing results. Autophagy cannot be activated in the presence of insulin.
Autophagy progresses unabated, accelerating up to 30% or more. After two days without food, the immune system begins to repair and regenerate. The inflammatory process is notably reduced as lipolysis is maintained. Toxins continue to be released as damaged molecules within the cells are broken down.
Autophagy continues to work its magic. Many of the benefits attributed to calorie-restriction stem from autophagy. The lower the levels of insulin are, the higher the rate of autophagy, which after three days of fasting can increase up to five fold. Like many other processes in the body, autophagy declines with age.
As the rate of autophagy slows, cellular debris begins to accumulate. Insulin resistance, which is epidemic in today’s society, accentuates the problem by further inhibiting autophagy. This reduced rate likely accounts for many of the negative effects of obesity and diabetes. Fasting is a fantastic way to reset autophagy. Keep in mind, if you’re going to fast for 72 hours, once a season is enough.
Autophagy and toxin-release can create a detox or Herxheimer’s reaction. Binders and clays can be helpful for mopping up mobilized toxins before they can be recirculated. Common detox reactions may include headaches, joint pain, skin rashes and breakouts, irritability, insomnia, and fatigue.
If you experience any of these symptoms, step up your detox strategies. Colonics, coffee enemas, rebounding, exercise, epsom salt baths, and saunas are all effective methods to eliminate toxicity. Also, drink plenty of filtered water to stay hydrated and foster the release of toxins.
Aging is the result of the body’s inability to repair and recycle. When damage accumulates, the signs of aging become visible. Fasting, through the stimulation of autophagy, can reset the rate at which the body is able to repair and heal. There’s not a better strategy to look and feel younger longer.
What are your experiences with fasting? Did you know many of its beneficial effects are attributed to autophagy? Let me know in the comments:)