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Gut Reactions notes
Apr. 5th, 2021 12:22 pm* after a time of little or no sugar in the diet, the brain and tongue reprogram themselves to detect much lower amounts of sweet. things that never tasted sweet before now taste sweet.
* in nature sugar is usually found as sucrose, a molecule composed of two simple sugars: glucose and fructose. we call them carbohydrates because they are made of carbon and water. your body has to use a tiny bit of energy to break the molecule apart into the two simple sugars. glucose can be used immediately by muscles, brains, and other organs. fructose is sent to the liver for processing.
* fructose does not raise insulin levels. Thus the appetite stimulating hormone grehlin is still produced, and we still feel hungry. the satiety hormone leptin is not produced, so we don't feel full.
the glucose receptors in the brain's hypothalamus that tell us to stop feeding are not activated. the tasty food is still in front of us and our homeostasis mechanism aren't kicking in to stop us from overeating.
eating a high fructose meal leads to high levels of fat, triglicerides, even when the same total number of calories is controlled for. about 30% of the fructose is turned into fat in the liver, much of this extra fat is stored in the liver where it was produced, not in fat cells elsewhere in the body. excess liver fat causes the same kind of liver disease as excess alcohol consumption. (Non-alcoholic fatty liver disease.) Fat in and around the liver, known as visceral fat, abdominal fat, or beer belly, is the dangerous fat associated with heart disease, stroke, and diabeties.
not all the fat from fructose is stored however. some of it leaks out into the blood as free fatty acids, those cause the muscle cells to become less sensitive to insulin. they no longer hear the signal to burn glucose so the glucose must be removed from the blood by the fat cells which store it as fat.
in the liver, fructose metabolism creates the inflammatory molecule JNK1. interferes with insulin receptors in the liver cells. the liver becomes insensitive to insulin, so it does not hear the insulin signal telling it to stop converting stored glycogen into bloodsugar. Bloodsugar rises, prompting more insulin production. the muscle and liver aren't listening to that signal, so the fat cells have to remove the sugar, and store it as fat.
(interrupted by husband, at 30:05 of book)
fructose does more damage than simply adding fat. it causes heart disease by making the liver produce too much uric acid. uric acid raises blood pressure by reducing nitric acid production. nitric acid is the molecule that makes blood vessels dilate, lowering blood pressure. it is what nitroglycerin tablets release into the blood to relieve angina. uric acid is what causes gout. the high insulin levels raise blood pressure, combined with the uric acid the prevents the blood vessels from getting the nitric oxide signal to dilate. we now have two signals leading to hypertension.
the high insulin levels also interfere with the brain's leptin receptors. Leptin is the hormone that tells the brain to stop eating. Leptin also reduces the reward signals that we get in the brain from eating, so eating more isn't as much fun.
(31:18)
* in nature sugar is usually found as sucrose, a molecule composed of two simple sugars: glucose and fructose. we call them carbohydrates because they are made of carbon and water. your body has to use a tiny bit of energy to break the molecule apart into the two simple sugars. glucose can be used immediately by muscles, brains, and other organs. fructose is sent to the liver for processing.
* fructose does not raise insulin levels. Thus the appetite stimulating hormone grehlin is still produced, and we still feel hungry. the satiety hormone leptin is not produced, so we don't feel full.
the glucose receptors in the brain's hypothalamus that tell us to stop feeding are not activated. the tasty food is still in front of us and our homeostasis mechanism aren't kicking in to stop us from overeating.
eating a high fructose meal leads to high levels of fat, triglicerides, even when the same total number of calories is controlled for. about 30% of the fructose is turned into fat in the liver, much of this extra fat is stored in the liver where it was produced, not in fat cells elsewhere in the body. excess liver fat causes the same kind of liver disease as excess alcohol consumption. (Non-alcoholic fatty liver disease.) Fat in and around the liver, known as visceral fat, abdominal fat, or beer belly, is the dangerous fat associated with heart disease, stroke, and diabeties.
not all the fat from fructose is stored however. some of it leaks out into the blood as free fatty acids, those cause the muscle cells to become less sensitive to insulin. they no longer hear the signal to burn glucose so the glucose must be removed from the blood by the fat cells which store it as fat.
in the liver, fructose metabolism creates the inflammatory molecule JNK1. interferes with insulin receptors in the liver cells. the liver becomes insensitive to insulin, so it does not hear the insulin signal telling it to stop converting stored glycogen into bloodsugar. Bloodsugar rises, prompting more insulin production. the muscle and liver aren't listening to that signal, so the fat cells have to remove the sugar, and store it as fat.
(interrupted by husband, at 30:05 of book)
fructose does more damage than simply adding fat. it causes heart disease by making the liver produce too much uric acid. uric acid raises blood pressure by reducing nitric acid production. nitric acid is the molecule that makes blood vessels dilate, lowering blood pressure. it is what nitroglycerin tablets release into the blood to relieve angina. uric acid is what causes gout. the high insulin levels raise blood pressure, combined with the uric acid the prevents the blood vessels from getting the nitric oxide signal to dilate. we now have two signals leading to hypertension.
the high insulin levels also interfere with the brain's leptin receptors. Leptin is the hormone that tells the brain to stop eating. Leptin also reduces the reward signals that we get in the brain from eating, so eating more isn't as much fun.
(31:18)
