Jason Fung Quotes

“A fourteen-day fast delivers seven times the benefit of a two-day fast but is only marginally more difficult.”

“Because consistently high insulin levels are the root cause of all the diseases of metabolic syndrome, it’s especially important for those with metabolic syndrome to consider how foods stimulate the release of insulin.”

“Fasting has no upper limit.”

“Fasting improves mental clarity and concentration and induces weight and body fat loss.”

“Fasting is not so much a treatment for illness but a treatment for wellness.”

“Fasting, by taking a completely different approach, is much easier to understand. It is so simple that it can be explained in two sentences: Eat nothing. Drink water, tea, coffee, or bone broth. That’s it.”

“Hunger is a state of mind, not a state of stomach.”

“If you feast, you must fast.”

“Interestingly, I’ve seen the highest success rates with husbands and wives who try fasting together: the mutual support is a big help and makes fasting far easier.”

“Myth #3: Fasting causes low blood sugar

Sometimes people worry that blood sugar will fall very low during fasting and they will become shaky and sweaty. Luckily, this does not actually happen.

Blood sugar level is tightly monitored by the body, and there are multiple mechanisms to keep it in the proper range.

During fasting, our body begins by breaking down glycogen (remember, that’s the glucose in short-term storage) in the liver to provide glucose. This happens every night as you sleep to keep blood sugars normal as you fast overnight.

People who engage in fasting for religious or spiritual purposes often report feelings of extreme clear-headedness and physical and emotional well-being. Some even feel a sense of euphoria.

They usually attribute this to achieving some kind of spiritual enlightenment, but the truth is much more down-to-earth and scientific than that: it’s the ketones! Ketones are a 'superfood' for the brain.

When the body and brain are fueled primarily by fatty acids and ketones, respectively, the 'brain fog', mood swings, and emotional instability that are caused by wild fluctuations in blood sugar become a thing of the past and clear thinking is the new normal.

If you fast for longer than twenty-four to thirty-six hours, glycogen stores become depleted. The liver now can manufacture new glucose in a process called gluconeogenesis, using the glycerol that’s a by-product of the breakdown of fat.

This means that we do not need to eat glucose for our blood glucose levels to remain normal. A related myth is that brain cells can only use glucose for energy. This is incorrect.

Human brains, unique amongst animals, can also use ketone bodies—particles that are produced when fat is metabolized — as a fuel source. This allows us to function optimally even when food is not readily available. Ketones provide the majority of the energy we need.

Consider the consequences if glucose were absolutely necessary for brain function. After twenty-four hours without food, glucose stored in our bodies in the form of glycogen is depleted. At that point, we’d become blubbering idiots as our brains shut down.

In the Paleolithic era, our intellect was our only advantage against wild animals with their sharp claws, sharp fangs, and bulging muscles. Without it, humans would have become extinct long ago.

When glucose is not available, the body begins to burn fat and produce ketone bodies, which are able to cross the blood-brain barrier to feed the brain cells.

Up to 75 percent of the brain’s energy requirements can be met by ketones. Of course, that means that glucose still provides 25 percent of the brain’s energy requirements.”

“Practical experience with hundreds of patients shows that while they’re on an intermittent fasting regimen, they most often see their hunger diminish, not increase.”

“Some leading scientists, such as Dr. Thomas Seyfried, a professor of biology at Boston College, have proposed a yearly seven-day water-only fast.”

“Study of a religious forty-day fast found that baseline growth hormone levels increased from 0.73 ng/mL to peak at 9.86 ng/mL. That is a 1250 percent increase in growth hormone, all done without drugs.”

“The basics of good nutrition can be summarized in these simple rules.

Eat whole, unprocessed foods.
Avoid sugar.
Avoid refined grains.
Eat a diet high in natural fats.
Balance feeding with fasting.”

“The price of fasting is zero.”

“These studies all came to the same startling conclusion: the low-carb diet was significantly better for weight loss than the low-fat diet.

Even more stunning was that all the important risk factors for cardiovascular disease — including cholesterol, blood sugar level, and blood pressure — were also much improved on the low-carb diet.”

“Try to physically remove yourself from all food stimuli during a fast. Cooking a meal or even just seeing and smelling food while fasting is almost unbearably difficult.

This is not simply a matter of weak willpower. Our cephalic phase responses are fully activated, and to feel those responses without actually eating is like trying to stop a piranha feeding frenzy.

This, of course, is the same reason you should not shop for food when hungry, or keep snacks in the pantry.”

“We are wired for feast and famine, not feast, feast, feast.”