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The Many Health Benefits of Intermittent Fasting

About ten years ago, I watched a BBC documentary on aging and intermittent fasting produced by Dr. Michael Mosley. What I learned inspired me to integrate intermittent fasting into my lifestyle, and I encourage everyone to try it and experience the many amazing, truly unbelievable benefits.

As most of the research in this area is being done in the United States, the UK-based Dr. Mosley travelled to the National Institute on Aging in Maryland to interview Dr. Mark Mattson, who had originally introduced him to the concept of intermittent fasting. While there are many ways to fast, Mattson focuses on the approach where you eat normally for five days, but fast for two non-consecutive days a week (the 5:2 Diet). Mattson’s research found that intermittent fasting and caloric restriction can increase lifespan by 30% to 40% while slowing the processes that contribute to neurodegenerative disorders including Alzheimer’s, Parkinson’s, and ALS. More recently, Mattson has produced research indicating that intermittent fasting builds brain neurons, increases HGH (human growth hormone), decreases oxidative stress, decreases insulin levels, reduces inflammation, and lowers blood pressure. In addition to the health benefits, it's a great way to lose weight, too.

During fasting, HGH increases as much as five-fold, which can help increase muscle and reduce fat. Insulin levels drop when we fast, while glucagon levels rise. A hormone with effects opposite to insulin, glucagon helps control blood glucose levels and restore insulin sensitivity, which can improve symptoms of Type 2 diabetes, prediabetes, and polycystic ovarian syndrome. Fasting also increases the release of norepinephrine, the fat-burning hormone.

Dr. Jason Fung, a nephrologist in Ontario, has been successfully treating patients with Type 2 diabetes using fasting and a ketogenic diet. I referred a client who was an insulin-dependent diabetic to Dr. Fung, and in about 10 months, she no longer required insulin or any drugs to control her diabetes. Dr. Fung is the author of The Complete Guide to Fasting, the most comprehensive book ever written on the many health benefits of fasting.

Two key features of fasting are autophagy, a cellular repair process where cells eliminate and "recycle" old and dysfunctional proteins, and ketosis, where the body uses fat for energy instead of glucose (sugar).


Yoshinori Ohsumi won the Nobel Prize in Medicine for his autophagy research, where he confirmed that this natural process switches on during nutrient deprivation and from exercise. Fasting from 12 to 36 hours lowers insulin levels and allows glucagon to eliminate damaged or diseased cells while promoting the generation of growth hormone and new cells (including brain cells). The increase in glucagon during fasting boosts autophagy.

The autophagic process works to reduce inflammation and strengthen the immune system. The word is derived from the Greek auto (self), and phagein (to eat), so autophagy means "self-eating." It's a mechanism where the body gets rid of old dysfunctional cells (including cancer cells and toxic proteins that accumulate in the brain) while recycling and repairing when possible. Autophagy may be the most powerful system in the body for slowing down the aging process, as it creates younger cells while eliminating cells that are no longer functioning well. In addition, autophagy removes harmful proteins like tau and beta-amyloid that are associated with neurodegenerative diseases. Eating turns off autophagy, so any glucose, proteins, or even a single amino acid will stop the process. It's also unique to fasting, so it isn't turned on by caloric restriction. One interesting exception is curcumin (the bioactive component in turmeric spice) which has been shown in many studies to induce autophagy.


Another major benefit of fasting is ketosis, a metabolic state that occurs when you reduce your consumption of carbohydrates. Ketosis happens during fasting, or by limiting carbohydrate consumption to 20 to 50 grams per day. The ketogenic or “keto” diet is very high in fat, low in carbohydrates, and low to moderate in protein consumption. Ketones (also called ketone bodies) are an alternate fuel produced by the liver from stored fat when there is not enough glucose available for energy. In other words, when your body doesn't have enough sugar for immediate use, it needs to find an alternate source of energy. It switches to breaking down fat, and this produces ketones. The liver then releases the ketones into the bloodstream to be used as fuel to support muscle function and metabolism. You can use ketone testing strips to determine if you are in the ketogenic state; they simply detect the presence of ketones in the urine.

When the body produces ketones for energy, a is not required to push the ketones into the cells as it is with glucose. An important added benefit is that when the body burns fat for fuel, insulin sensitivity is restored, resulting not only in weight loss, but reducing the risk of diabetes while boosting brain function.

While most people are interested in the ketogenic diet because it's a great way to lose weight, it’s been used therapeutically for over a hundred years to treat epileptic seizures in children. There's an increasing body of research that indicates the ketogenic diet results in cognitive, psychological, and physical health benefits. While the brain prefers glucose for fuel because it's metabolized quickly, glucose is not clean-burning, and it leaves debris in the mitochondria (the energy furnaces in our cells). Glucose also produces reactive oxygen species (free radicals that damage cells). This oxidative stress contributes to the production of toxic proteins in the brain that are associated with cognitive impairment and Alzheimer's disease. This process where the brain becomes resistant to insulin is sometimes called "Type 3 diabetes", and may contribute to depression and other psychiatric disorders. When brain cells use fat (as ketones) for fuel, the oxidative damage in brain cells is curtailed.

Ketosis is a fantastic weight loss method, as the body uses stored fat instead of carbs for energy. A study of 34 older adults found that an eight-week ketogenic diet resulted in five times the fat loss, as compared to a standard low-fat diet. Other benefits include improving insulin sensitivity by as much as 75%. Innotech Nutrition developed a delicious low-calorie drink called Fasting Days that provides amino acids, minerals, and vitamins that can help curb hunger and make it easier to stay in ketosis. The nutrient support can also help alleviate leg cramps that some people experience when fasting.

Fasting Plate

Often when I tell people about the benefits of fasting, they assume they’ll be hungry all the time. It may seem counter-intuitive, but once you get used to fasting, you notice that you aren’t hungry. Often, just a large glass of water, which expands the stomach (I add some fresh lemon juice) eliminates the hunger pangs. When sourcing energy from fat, energy levels actually increase and are sustained throughout the day rather than spiking and crashing.
One of the marvelous physiological changes that takes place during fasting (after about three days in ketosis) is gluconeogenesis, where the liver and kidneys begin to turn fat into glucose that the body can use for fuel and energy. This is the process that results in fat loss and facilitates all the benefits of fasting.

As I've gotten older, I’ve found it more difficult to maintain my ideal weight. Intermittent fasting helps me to normalize my weight, and I love that I can thoroughly enjoy eating on my "non-fasting" days, knowing that my fasting days will even things out. I also feel we should do everything we can to maximize growth hormone and brain function; both are supported by fasting, among its many other remarkable health benefits.

Health Disclaimer. Copyright ©2021. Nathan Zassman is a trained nutrition practitioner and the owner of Aviva Natural Health Solutions.

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