Post by kewlkat on Nov 16, 2013 9:36:13 GMT -6
I recently discovered the subject book, full text PDF, and thought I'd share the link here since it may be of interest.
The Ketogenic Diet by Lyle McDonald
I've just begun reading this today but here are a few snippets that were of special interest to me -
Page 16 -
Somewhat difficult to understand is why ketogenic diets have been readily accepted as medical treatment for certain conditions but are so equally decried when mentioned for fat loss. Most of the criticisms of ketogenic diets for fat loss revolve around the purported negative health effects (i.e. kidney damage) or misconceptions about ketogenic metabolism (i.e. ketones are made out of protein).
This begs the question of why a diet presumed so dangerous for fat loss is being used clinically without problem. Pediatric epilepsy patients are routinely kept in deep ketosis for periods up to 3 years, and occasionally longer, with few ill effects (3,5). Yet the mention of a brief stint on a ketogenic diet for fat loss and many people will comment about kidney and liver damage, ketoacidosis, muscle loss, etc. If these side effects occurred due to a ketogenic diet, we would expect to see them in epileptic children.
Page 21 -
Most tissues of the body can use FFA for fuel if it is available. This includes skeletal muscle, the heart, and most organs. However, there are other tissues such as the brain, red blood cells, the renal medulla, bone marrow and Type II muscle fibers which cannot use FFA and require glucose (2).
The fact that the brain is incapable of using FFA for fuel has led to one of the biggest misconceptions about human physiology: that the brain can only use glucose for fuel. While it is true that the brain normally runs on glucose, the brain will readily use ketones for fuel if they are available (4-6).
Arguably the most important tissue in terms of ketone utilization is the brain which can derive up to 75% of its total energy requirements from ketones after adaptation (4-6). In all likelihood, ketones exist primarily to provide a fat-derived fuel for the brain during periods when carbohydrates are unavailable (2,7).
As with glucose and FFA, the utilization of ketones is related to their availability (7). Under normal dietary conditions, ketone concentrations are so low that ketones provide a negligible amount of energy to the tissues of the body (5,8). If ketone concentrations increase, most tissues in the body will begin to derive some portion of their energy requirements from ketones (9). Some research also suggests that ketones are the preferred fuel of many tissues (9). One exception is the liver which does not use ketones for fuel, relying instead on FFA (7,10,11).
As ketosis develops, most tissues which can use ketones for fuel will stop using them to a significant degree by the third week (7,9). This decrease in ketone utilization occurs due to a down regulation of the enzymes responsible for ketone use and occurs in all tissues except the brain (7). After three weeks, most tissues will meet their energy requirements almost exclusively through the breakdown of FFA (9). This is thought to be an adaptation to ensure adequate ketone levels for the brain.
Page 22 -
With chronically overfilled glycogen stores and a high carbohydrate intake, fat utilization is almost completely blocked and any dietary fat consumed is stored.
This has led some authors to suggest an absolute minimization of dietary fat for weight loss (15,16). The premise is that, since incoming carbohydrate will block fat burning by the body, less fat must be eaten to avoid storage. The ketogenic diet approaches this problem from the opposite direction. By reducing carbohydrate intake to minimum levels, fat utilization by the body is maximized.
The Ketogenic Diet by Lyle McDonald
I've just begun reading this today but here are a few snippets that were of special interest to me -
Page 16 -
Somewhat difficult to understand is why ketogenic diets have been readily accepted as medical treatment for certain conditions but are so equally decried when mentioned for fat loss. Most of the criticisms of ketogenic diets for fat loss revolve around the purported negative health effects (i.e. kidney damage) or misconceptions about ketogenic metabolism (i.e. ketones are made out of protein).
This begs the question of why a diet presumed so dangerous for fat loss is being used clinically without problem. Pediatric epilepsy patients are routinely kept in deep ketosis for periods up to 3 years, and occasionally longer, with few ill effects (3,5). Yet the mention of a brief stint on a ketogenic diet for fat loss and many people will comment about kidney and liver damage, ketoacidosis, muscle loss, etc. If these side effects occurred due to a ketogenic diet, we would expect to see them in epileptic children.
Page 21 -
Most tissues of the body can use FFA for fuel if it is available. This includes skeletal muscle, the heart, and most organs. However, there are other tissues such as the brain, red blood cells, the renal medulla, bone marrow and Type II muscle fibers which cannot use FFA and require glucose (2).
The fact that the brain is incapable of using FFA for fuel has led to one of the biggest misconceptions about human physiology: that the brain can only use glucose for fuel. While it is true that the brain normally runs on glucose, the brain will readily use ketones for fuel if they are available (4-6).
Arguably the most important tissue in terms of ketone utilization is the brain which can derive up to 75% of its total energy requirements from ketones after adaptation (4-6). In all likelihood, ketones exist primarily to provide a fat-derived fuel for the brain during periods when carbohydrates are unavailable (2,7).
As with glucose and FFA, the utilization of ketones is related to their availability (7). Under normal dietary conditions, ketone concentrations are so low that ketones provide a negligible amount of energy to the tissues of the body (5,8). If ketone concentrations increase, most tissues in the body will begin to derive some portion of their energy requirements from ketones (9). Some research also suggests that ketones are the preferred fuel of many tissues (9). One exception is the liver which does not use ketones for fuel, relying instead on FFA (7,10,11).
As ketosis develops, most tissues which can use ketones for fuel will stop using them to a significant degree by the third week (7,9). This decrease in ketone utilization occurs due to a down regulation of the enzymes responsible for ketone use and occurs in all tissues except the brain (7). After three weeks, most tissues will meet their energy requirements almost exclusively through the breakdown of FFA (9). This is thought to be an adaptation to ensure adequate ketone levels for the brain.
Page 22 -
With chronically overfilled glycogen stores and a high carbohydrate intake, fat utilization is almost completely blocked and any dietary fat consumed is stored.
This has led some authors to suggest an absolute minimization of dietary fat for weight loss (15,16). The premise is that, since incoming carbohydrate will block fat burning by the body, less fat must be eaten to avoid storage. The ketogenic diet approaches this problem from the opposite direction. By reducing carbohydrate intake to minimum levels, fat utilization by the body is maximized.
