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Originally Posted by Samuel
Although ketosis is the basic subject on which low carb diets are based, Each one of us seems to have his own explanation of this subject.
Even Dr. Atkins himself despite my great respect for him has mentioned a phrase in his book about ketosis which I can't agree with. His phrase was:
"There is no lipolysis without ketosis, no ketosis without lipolysis."
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It depends how you define ketosis. It's false if you define ketosis as measurable ketosis (meaning tasting nailpolish breath, being real thirsty, having no appetite, turning a strip pink, whatever measure you use to estimate ketone concentration). It's true if you use the most literal definition of ketosis as meaning "breaking down fat into energy producing some ketones". You cannot break down fat (lipolysis) without creating a ketogenic state (ketosis). It's simply impossible. However it is entirely possible to break down such a small quantity of fat that ketosis is undetectable (for example, a normal diet or even a moderate low fat weight loss diet - in which the small amount of fat comes from diet and/or body fat)
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If there was no lipolysis without ketosis we could have seen that the people who are on high carb low calorie diet who lose plenty of weight produce a large amounts of ketones, but this is not true.
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Not necessarily. Carbohydrate sensitivity excluded for simplicity of understanding, people on low fat diets who lose weight are producing ketones from burning body fat. The caloric deficit forces them to draw on body fat stores, which they then break down into ketones. It's just that the majority of their energy needs are met from dietary glucose so ketone concentration never rises to the point where it is detectable, the same way people on a normal fat calorie-adequate rarely have detectable amounts of ketones in their bodies because dietary fat is too small a percentage of energy for ketone concentration to be noticeable.
Sometimes even people on low fat diets or normal diets can have ketone concentration rise enough so it's detectable. It's not uncommon for individuals who like to exercise first thing in the morning to detect ketosis afterward. Of course this stops when they eat and there body burns sugar for energy again.
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And if there was no ketosis without liplysis we would not have seen low carb dieters who are not losing or even gaining weight while noticing high concentration of ketones in their urine. The source of theiir ketones must be dietary fat.
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There can be no ketosis without lipolysis. Lipolysis does not mean "weight loss" lipolysis means "breaking down fat into usable energy" (i.e. ketones). People who fail to lose weight on ketogenic diets are simply eating too much caloric energy from dietary fats for their metabolism, so no energy deficit is created and the body does not burn it's own fats. This uncommon phenomena (uncommon because the limited/boring nature of a ketogenic diet combined with its potent anorexic effect usually means some weight loss) does not invalidate the statement. All it means is that ketosis does not help everyone eat less and lose weight.
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Here is my explanation for the subject of ketosis:
There are two methods to metabolize fats:
(1) The default method in which fatty acids go through series of processes and end with a fuel which is used for energy. After all the body's energy needs are met, the left over energy is stored as body fat.
(2) The second method in which fatty acids break into ketone bodies and a different kind of fatty acids (shorter in chain length) before they complete their journey. Ketones supply body cells with energy. After all energy needs are met, ketones can only exit the body. They cannot be stored as body fat.
To my believe, the body uses the first method alone when carb intake exceeds (100-120) carbs depending on the individual.
When carb intake is reduced below this amount, the two methods take place at the same time and method 2 share grows as the carb intake moves down twards zero.
So carb reduction acts like moving a mode switch slowly from one extreme to another. The first extreme is for a fully vegetarian human (during the pre-agriculture era) and the second extreme is for a fully meat eating human.
The vegetarian human can metabolize fats, but probably not the perfect way. The meat eating human metabolizes fats better and safer.
Ketones do not appear in the urine or saliva until they exceed the amount the body can use. This is why you don't notice them unless you eat 35 carbs or less.
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What troubles me about your theory is that it doesn't seem based on anything observable.
1) IF fats are metabolized differently depending on the presence of dietary carbohydrate, what is the nature of the "other way"?
I know carbohydrate encourages storage because carbohydrate promotes insulin, and I also know that the body prefers to utilize carbohydrate and store fat since this is the "thriftiest" route. So, if you eat caloric excess, the body is more likely to store the fat and not burn it. Complicating matters further, the level at which "excess" happens decreases the higher percentage of carbohydrate you eat (since it is more metabolically efficient for the body to use carbohydrate as fuel, less calories are burned and the point at which dietary fat stops being burned and starts being stored gets increasingly less generous).
2) I do not believe it is impossible to store fat on a ketogenic diet. I believe it is less likely since appetite is usually crushed and the body is better at burning fat & metabolism is generally higher. I don't believe it is impossible. The only only way fail to store fat is if there is a deficit of insulin of such a magnitude that one is
diseased, like T1 DM. Without insulin more things happen besides not being able to store fat. You get out of control fat burning, you get ketoacidosis, hyperglycemia as the body keeps making & dumping more sugar from protein. You die very quickly.
Basically what I'm saying is this. If it were true that eating only fat created a deficit of insulin to the point where it was IMPOSSIBLE to store fat, then it would also be true that a deficit of insulin of that magnitude would create numerous other side effects which were less desirable and quite fatal. It is , quite simply,
an abnormality to not be able to store fat. It is a normal function of a normal body. If the body can't store fat that also means it can't do other essential things.