QUOTE from Dr Fung (emphasis mine):
“THE BODY’S RESPONSE TO FASTING: GLUCOSE AND FAT are the body’s main sources of energy. When glucose is not available, then the body adjusts by using fat, without any health detriment. This compensation is a natural part of life. Periodic food scarcity has always been part of human history, and our bodies have evolved processes to deal with this fact of Paleolithic life. The transition from the fed state to the fasted state occurs in several stages:
Feeding: During meals, insulin levels are raised. This allows glucose uptake by tissues such as the muscle or brain for direct use as energy. Excess glucose is stored as glycogen in the liver.
The post-absorptive phase (six to twenty-four hours after fasting starts): Insulin levels begin to fall. The breakdown of glycogen releases glucose for energy. Glycogen stores last for roughly twenty-four hours.
Gluconeogenesis (twenty-four hours to two days): The liver manufactures new glucose from amino acids and glycerol. In non-diabetic persons, glucose levels fall but stay within the normal range.
Ketosis (one to three days after fasting starts): The storage form of fat, triglycerides, is broken into the glycerol backbone and three fatty acid chains. Glycerol is used for gluconeogenesis. Fatty acids may be used directly for energy by many tissues in the body, but not the brain. Ketone bodies, capable of crossing the blood-brain barrier, are produced from fatty acids for use by the brain. Ketones can supply up to 75 percent of the energy used by the brain.4 The two major types of ketones produced are beta hydroxybutyrate and acetoacetate, which can increase more than seventy-fold during fasting.5
Protein conservation phase (after five days): High levels of growth hormone maintain muscle mass and lean tissues. The energy for maintenance of basal metabolism is almost entirely met by the use of free fatty acids and ketones. Increased norepinephrine (adrenalin) levels prevent the decrease in metabolic rate.”
NOTE – What does it say?
When glucose is not available, then the body adjusts by using fat, without any health detriment. This is normal; that’s the purpose of the body retaining fat for energy. Consequently, in order to lose weight, to decrease fat on the body, we can stop making external glucose available.
During meals, insulin levels are raised; 6 to 24 hours after fasting starts, insulin levels begin to fall. After 24 hours to two days of fasting, the body is in a state of gluconeogenesis, where the liver manufactures new glucose from amino acids and glycerol. One to three days after fasting starts, the body is now adjusted to efficiently burn fat for fuel.
After 5 days of fasting, a variety of mechanisms operate to protect the body from losing protein in the form of muscle mass and lean tissue. The energy for metabolism is almost entirely met by the use of free fatty acids and ketones, a byproduct of burning fat. Increased adrenalin keeps metabolic levels high when fasting. Energy is needed, after all, to hunt and search for food when one is not eating.
What does it say that we need to obey?
I need to be aware of the stages my body goes through based on how long a time between meals.
STRATEGY: My goal is to establish a habit of the IDM building blocks – fast three days a week, either 24 hours (supper to supper), the Varady diet, or 36 hours (supper to breakfast).
What gets my attention?
Do I understand the need or problem?
Do I understand the potential solution?
Do I understand how to apply that strategy?
What questions do I have for the experts? What might be the answers?
Who needs to hear this?
What do I do next?
SOURCE – Footnotes:
 Quote from The Obesity Code: Unlocking the Secrets of Weight Loss by Dr. Jason Fung; Greystone Books (March 3, 2016). Page 238.
Photo Fasting-a-glass-of-water-on-an-empty-plate, via Wikimedia Commons
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Key: Fung-11 Last Revision: 02/19/2021