Hi everybody, I'm a zoner based in Milan - Italy, where we have a similar forum. I have been following with great interest and hugely benefited from drsears.com forum. I have in many occasions shared with other Italian zoners all the relevant information I've gathered in here. Now I want to put to you some of the questions I've not found a decisive answer yet. I start with one today. In some textbooks on Biochemistry (like the classical from Lehninger et al.) is written that around 120g is the daily consumption of glucose by the brain. This amount is almost independent on sex, age etc. Considering that other organs also consume some glucose, not to mention the consumption by the skeleton muscles, a normal and healthy human shoud need some 140g of carbs per day to say the least. How does the Zone go along with this? If we consider a 11 block menu with a standard P/C ratio of 0,75, we get only 100g of carbs. Can it be this arguably insufficient amount of carbs the explanation of the difficulties encountered by some female candidates to stick to the Zone diet in an early trial conducted by Sears, that made him recommend at least 11 blocks, regardless of the LBM? Should it be any negative correlation between the number of blocks and the P/C ratio, e.g. a 11 block diet commands a P/C of 0.6, in order to ensure at least 120g of carbs daily? I would appreciate your comments on this issue, thanks, Gent

[quote:32cd9c3046="Gent"] In some textbooks on Biochemistry (like the classical from Lehninger et al.) is written that around 120g is the daily consumption of glucose by the brain. This amount is almost independent on sex, age etc. Considering that other organs also consume some glucose, not to mention the consumption by the skeleton muscles, a normal and healthy human shoud need some 140g of carbs per day to say the least. How does the Zone go along with this? [/quote:32cd9c3046] My initial oberservation would be how they came up with these figures. The background diet can influence how much glucose from external sources is needed to feed the brain/muscles. I'd be interested in knowing what the average fasting insulin level was for the work done in this area.

Hi Gent, [quote:e730d058f1="Gent"]Hi everybody, I'm a zoner based in Milan - Italy, where we have a similar forum. I have been following with great interest and hugely benefited from drsears.com forum. I have in many occasions shared with other Italian zoners all the relevant information I've gathered in here. Now I want to put to you some of the questions I've not found a decisive answer yet. I start with one today. In some textbooks on Biochemistry (like the classical from Lehninger et al.) is written that around 120g is the daily consumption of glucose by the brain. This amount is almost independent on sex, age etc. Considering that other organs also consume some glucose, not to mention the consumption by the skeleton muscles, a normal and healthy human shoud need some 140g of carbs per day to say the least. How does the Zone go along with this? If we consider a 11 block menu with a standard P/C ratio of 0,75, we get only 100g of carbs. Can it be this arguably insufficient amount of carbs the explanation of the difficulties encountered by some female candidates to stick to the Zone diet in an early trial conducted by Sears, that made him recommend at least 11 blocks, regardless of the LBM? Should it be any negative correlation between the number of blocks and the P/C ratio, e.g. a 11 block diet commands a P/C of 0.6, in order to ensure at least 120g of carbs daily? I would appreciate your comments on this issue, thanks, Gent[/quote:e730d058f1] Carbs are not the only source of fuel for the brain If they were Aitkins would not work for most people.(they would die) The body is able to adapt with just protein and fat. (but that is not ideal) White Light

Hi Scott, [quote:f204590537="Scott"] My initial oberservation would be how they came up with these figures. [/quote:f204590537] I haven’t found it as yet. But let’s take it for granted for a moment. [quote:f204590537] The background diet can influence how much glucose from external sources is needed to feed the brain/muscles. I'd be interested in knowing what the average fasting insulin level was for the work done in this area.[/quote:f204590537] Hi WL, [quote:f204590537="White Light"] Carbs are not the only source of fuel for the brain If they were Aitkins would not work for most people.(they would die) The body is able to adapt with just protein and fat. (but that is not ideal) [/quote:f204590537] While it is true that the background diet can influence how much glucose from external sources is needed to feed the muscles, it seems that the consumption of the brain, the nervous system, the medullar part of the kidneys, the testicles and the red blood cells use almost exclusively glucose, and the amount is more or less constant over time, day and night. If this is true, then, in order to meet the need for glucose, proteins will be used and the gluconeogenesis process intensified. It is true that the brain may use also ketones as fuel and it does so always, but only marginally when in a Zone diet, and extensively in the Atkins one. If the gap between the need and the supply is relevant, protein catabolism will be inevitable. Sears has always excluded this. An alarm bell for such a process occurring will be an abnormal activity of the amminotransferase enzymes, especially of ALT and AST and altered values may be registered in serum blood. In our forum we’ve witnessed a number of such cases. I need 13 blocks and I’m in the Zone since June 2002. I have noticed increased values (just under or above the upper bound for normal values) for both ALT and AST during the Zone period with respect to the pre-Zone, in three different 6-months-distanced tests I’ve taken at the same test center. I decided four months ago to reduce my P/C to 0,6, and the last results (one month ago) were in line with the pre-Zone values. Sears (to my dismay) never mentions the glucose needs, perhaps because we can always produce some transforming proteins and recycling pyruvate and lactate into glucose. Sears has always excluded ketoses in the Zone, and this is true given that the minimum amount of carbs suggested is 100g. In any case, given that the Zone is assumed to be for life, even if only marginally the needs of the brain and other organs for glucose were satisfied though ketones or protein-derived glucose, in the long run this might be detrimental to the kidneys, liver and health in general. What do you think?

[quote:254950ebd1] While it is true that the background diet can influence how much glucose from external sources is needed to feed the muscles, it seems that the consumption of the brain, the nervous system, the medullar part of the kidneys, the testicles and the red blood cells use almost exclusively glucose, and the amount is more or less constant over time, day and night.[/quote:254950ebd1] I would think that if cravings are an indication of what the brain is requiring, it seems to me that its needs are dependent on the glycemic load of the diet. But let's say its constant-- the liver ideally should be supplying the glucose between meals. When fasting insulin levels are up, glycogenolysis (the breakdown of liver glycogen) is inhibited, and thus frequent feedings of glucose are necessary to keep the brain happy. Dietary glycemic load has an affect on glycogenolysis and the secretion of blood glucose between meals from the liver. The need to consume glucose goes down, if it is supplied by the liver between meals. Evidence of this is the decrease in cravings and hunger between meals as insulin levels lower. . If you combine the 100g for the minimum 11 blocks + the amount stored in the liver for between meals fasting, I would think that you would hit your 120-140g mark. [quote:254950ebd1]. If the gap between the need and the supply is relevant, protein catabolism will be inevitable. Sears has always excluded this.[/quote:254950ebd1] Sears article in the Journal of Advancement in Medicine discusses the catabolic state that develops when the glucagon/insulin ratio becomes too high. Sears, B. [i:254950ebd1]"Essential Fatty Acids and Dietary Endocrinology: A Hypothesis for Cardiovascular Treatment[/i:254950ebd1]" Journal of Advancement of Medicine, Vol. 6, No. 4, 1993 [quote:254950ebd1]An alarm bell for such a process occurring will be an abnormal activity of the amminotransferase enzymes, especially of ALT and AST and altered values may be registered in serum blood. In our forum we’ve witnessed a number of such cases. I need 13 blocks and I’m in the Zone since June 2002. I have noticed increased values (just under or above the upper bound for normal values) for both ALT and AST during the Zone period with respect to the pre-Zone, in three different 6-months-distanced tests I’ve taken at the same test center. I decided four months ago to reduce my P/C to 0,6, and the last results (one month ago) were in line with the pre-Zone values.[/quote:254950ebd1] I could find nothing to indicate why these enzymes would rise on a p/c ratio between .6-1.0. Were you on any medications at the time ALT/AST were above normal? Are you physically active enough that would necessitate higher glucose needs if not adding addtional fat? [quote:254950ebd1]Sears (to my dismay) never mentions the glucose needs, perhaps because we can always produce some transforming proteins and recycling pyruvate and lactate into glucose. Sears has always excluded ketoses in the Zone, and this is true given that the minimum amount of carbs suggested is 100g. In any case, given that the Zone is assumed to be for life, even if only marginally the needs of the brain and other organs for glucose were satisfied though ketones or protein-derived glucose, in the long run this might be detrimental to the kidneys, liver and health in general. What do you think?[/quote:254950ebd1] Sears glucose requirement are determined by the glucagon/insulin response that occurs when various amounts of carbohydrate are ingested with protein (1). I suppose that it is entirely possible that someone's p/c ratio could be off without realizing it, but how much of a detriment is it when a) you are not in ketosis and b) you are not hyperinsulinemic? There is no such thing as an essential carbohydrate and a number of cultures have existed on much lower carbohydrate amounts than the Zone without detriment. The only things I can think of would be a) side effects of medications b) higher physical activity without a corresponding increase in fat (or carbohydrate if not adhering to Sears dietary recommendations for higher physical activity) that results in gluconeogenesis. c) a p/c ratio of .6 is ideal for you. But I am not sure how the ALT/AST enzymes fit into this. (1) Westphal SA, et al "Metabolic response to glucose ingested with various amounts of protein." American Journal of Clinical Nutrition 1990;52;267-72

Hi Gent, [quote:8c76e14eb1] Hi WL, Carbs are not the only source of fuel for the brain If they were Aitkins would not work for most people.(they would die) The body is able to adapt with just protein and fat. (but that is not ideal) [/quote:8c76e14eb1] [quote:8c76e14eb1] While it is true that the background diet can influence how much glucose from external sources is needed to feed the muscles, it seems that the consumption of the brain, the nervous system, the medullar part of the kidneys, the testicles and the red blood cells use almost exclusively glucose, and the amount is more or less constant over time, day and night. If this is true, then, in order to meet the need for glucose, proteins will be used and the gluconeogenesis process intensified. It is true that the brain may use also ketones as fuel and it does so always, but only marginally when in a Zone diet, and extensively in the Atkins one. If the gap between the need and the supply is relevant, protein catabolism will be inevitable. Sears has always excluded this.?[/quote:8c76e14eb1] IMO this really depends totally on the individual and what they consume. While a high LBM high activity person may get 2 or 3* the so called min carbs for brain activity. Clearly an 11 blocker on drop a carb add a fat will not. In this case the brain glucose MUST come from protein (IMO) I am not aware that this specific question has been asked of DR. Sears. [quote:8c76e14eb1] An alarm bell for such a process occurring will be an abnormal activity of the amminotransferase enzymes, especially of ALT and AST and altered values may be registered in serum blood. In our forum we’ve witnessed a number of such cases. I need 13 blocks and I’m in the Zone since June 2002. I have noticed increased values (just under or above the upper bound for normal values) for both ALT and AST during the Zone period with respect to the pre-Zone, in three different 6-months-distanced tests I’ve taken at the same test center. I decided four months ago to reduce my P/C to 0,6, and the last results (one month ago) were in line with the pre-Zone values.?[/quote:8c76e14eb1] IMO many people are not able to achive perfect health regardless of nutrition. if some people eat the carbs they need (unbalanced) they elevate insulin and create worse problems [quote:8c76e14eb1] Sears (to my dismay) never mentions the glucose needs, perhaps because we can always produce some transforming proteins and recycling pyruvate and lactate into glucose. Sears has always excluded ketoses in the Zone, and this is true given that the minimum amount of carbs suggested is 100g. In any case, given that the Zone is assumed to be for life, even if only marginally the needs of the brain and other organs for glucose were satisfied though ketones or protein-derived glucose, in the long run this might be detrimental to the kidneys, liver and health in general. ?[/quote:8c76e14eb1] The vast majority do get adequate carbs and IMO those that dont, are worse off on a high carb diet. [quote:8c76e14eb1] What do you think?[/quote:8c76e14eb1] I think you should pose your Question directly to Dr. Sears (But don't hold your breath) White Light

Hi Scott, [quote:89952c2c85="Scott"] I would think that if cravings are an indication of what the brain is requiring, it seems to me that its needs are dependent on the glycemic load of the diet. But let's say its constant...(cut ... If you combine the 100g for the minimum 11 blocks + the amount stored in the liver for between meals fasting, I would think that you would hit your 120-140g mark. [/quote:89952c2c85] I am only wondering whether at 11 blocks one is perhaps far too close if not under her/his physiological needs of carbs. With the liver glycogene reserve may be possible to hit the target, but the reserve would sooner or later be entirely depleted, wouldn’t it. [quote:89952c2c85] Sears article in the Journal of Advancement in Medicine discusses the catabolic state that develops when the glucagon/insulin ratio becomes too high. [/quote:89952c2c85]. I mean that Sears has excluded that in the Zone carbs may be inufficient and that there will be a need for glucose to be produced from proteins, or ketones from the fatty acids for that matter. [quote:89952c2c85] I could find nothing to indicate why these enzymes would rise on a p/c ratio between .6-1.0. Were you on any medications at the time ALT/AST were above normal? Are you physically active enough that would necessitate higher glucose needs if not adding addtional fat? [/quote:89952c2c85] a) I know that some meds e.g. antibiotics, antidepressives etc. may cause as a side effect an alteration of ALT/AST, but I have not been been on any such drugs neither in the period preceding the test nor later; b) I am a healthy thirty-one years old guy doing my everyday 30’ aerobic exercise in the morning with an activity index of 1,5, and a 12-13% stable FBM. [quote:89952c2c85] Sears glucose requirement are determined by the glucagon/insulin response that occurs when various amounts of carbohydrate are ingested with protein (1). I suppose that it is entirely possible that someone's p/c ratio could be off without realizing it, but how much of a detriment is it when a) you are not in ketosis and b) you are not hyperinsulinemic? There is no such thing as an essential carbohydrate and a number of cultures have existed on much lower carbohydrate amounts than the Zone without detriment. [/quote:89952c2c85] Before the tests I was assuming 117g of carbs (13 blocks of 9g each) and I increased to 150g. I didn’t have cravings before that, I felt great, my bloodwork was great: HDL=99, TC=199, TG=30. I felt more or less the same even after increasing the carbs, I felt in Zone according to the eicosanoids checklist, my bloodwork: HDL=78, TC=159; TG=33. What I’m saying is that we should mind the total amount of carbs. If one is on 17 blocks then he could get more than 150g of carbs with a standard P/C ratio of 0,77. But if one goes with 11 blocks, to get 150g of carbs needs to go to a P/C of 0,5. Let me elaborate on this hypothesis. ALT/AST are enzymes involved in the catabolism of the proteins. The first stage of the catabolism of the most of amminoacids is promoted by such amminotransferrase enzymes. In such reactions the amminic group of the amminoacids is transferred to another element (alpha-ketogluturate) forming glutamic acid as an end product. The glutamic acid will donate this amminic group to pyruvate (produced by the glycolyses) thus forming alanine, which enters the blood and reaches the liver for further processing. In the liver the inverse reaction occurs, forming pyupvate (which is transformed through gluconeogenesis in glucose and enters the blood) and glutamic acid, which then releases the amminic group in the form of ammoniac that is qickly transformed in uric acid (free ammoniac is very toxic). In this reaction ALT (alanine-amminotransferrase is involved both in the muscle and in the liver. An alternative transformation fo the glutamic acid in the liver involves the AST (aspartate-amminotransferrase). This in brief what happens. Now, if the process of producing glucose from proteins and/or recycling of pyruvate as a precursor of glucose is significantly intensified and on a stable basis (not only after an intense sportive activity), in the long run the amount of ALT/AST would increase and be consistently registered in the blood serum. Also the level of azotemia in the urine would increase. It is exactly what happened with my values, the latter also just below the upper bound of the norm. In our forum, people with a higher sports activity that where on 14-15 blocks have witnessed both an increase (even well beyond the upper bound of the normal values) in ALT/AST and azotemia. They were reporting to feel great, their LBM being constant or increasing. Other sport active zoners that were on 18-20 blocks regime, didn’t report similar values. Off course the sample of my observations is too small and I might be in a certain sense biased toward believing what I think might be the reason. In any case, I thought it was worth looking beyond the metabolic and hormonal response our body has to certain amounts of carbs and proteins and figure out whether there were limits there to be respected. And so I read “The principles of biochemistry” (1993 Worth publishers) by Lehninger, Nelson and Cox. Mine is only a speculation that I wanted to discuss in this forum, I haven’t found specific research to support or deny it as yet. Thanks for your thought and research citing, Scott. I have looked even earlier, but could not find the artile of Sears in the Pubmed. Can you show me the link to it? Hi WL, I believe I answered your observations above. [quote:89952c2c85]I think you should pose your Question directly to Dr. Sears (But don't hold your breath) [/quote:89952c2c85] I am thinking to do it. Thanks again.

[quote:2e9f705ae4="Gent"] I am only wondering whether at 11 blocks one is perhaps far too close if not under her/his physiological needs of carbs. With the liver glycogene reserve may be possible to hit the target, but the reserve would sooner or later be entirely depleted, wouldn’t it. [/quote:2e9f705ae4] That crossed my mind as well. [quote:2e9f705ae4] Before the tests I was assuming 117g of carbs (13 blocks of 9g each) and I increased to 150g. I didn’t have cravings before that, I felt great, my bloodwork was great: HDL=99, TC=199, TG=30. I felt more or less the same even after increasing the carbs, I felt in Zone according to the eicosanoids checklist, my bloodwork: HDL=78, TC=159; TG=33. What I’m saying is that we should mind the total amount of carbs. If one is on 17 blocks then he could get more than 150g of carbs with a standard P/C ratio of 0,77. But if one goes with 11 blocks, to get 150g of carbs needs to go to a P/C of 0,5.[/quote:2e9f705ae4] Thanks for the detail--it definitely makes it easier to see the question from your perspective. [quote:2e9f705ae4] Now, if the process of producing glucose from proteins and/or recycling of pyruvate as a precursor of glucose is significantly intensified and on a stable basis (not only after an intense sportive activity), in the long run the amount of ALT/AST would increase and be consistently registered in the blood serum. Also the level of azotemia in the urine would increase. It is exactly what happened with my values, the latter also just below the upper bound of the norm. In our forum, people with a higher sports activity that where on 14-15 blocks have witnessed both an increase (even well beyond the upper bound of the normal values) in ALT/AST and azotemia. They were reporting to feel great, their LBM being constant or increasing. Other sport active zoners that were on 18-20 blocks regime, didn’t report similar values. [/quote:2e9f705ae4] Thanks for elaborating. If ALT/AST enzymes are involved in the catabolism of protein, why would an increase in LBM be experienced? I can definitely understand why ALT/AST would increase for a higher level of physical activity who aren't adding enough fat or carbs or total blocks and are subject to muscle wasting. [quote:2e9f705ae4]Off course the sample of my observations is too small and I might be in a certain sense biased toward believing what I think might be the reason. In any case, I thought it was worth looking beyond the metabolic and hormonal response our body has to certain amounts of carbs and proteins and figure out whether there were limits there to be respected. And so I read “The principles of biochemistry” (1993 Worth publishers) by Lehninger, Nelson and Cox. Mine is only a speculation that I wanted to discuss in this forum, I haven’t found specific research to support or deny it as yet.[/quote:2e9f705ae4] Its definitely worth looking at. I wonder if increasing the number of blocks as opposed to lowering the p/c ratio would be a better solution? This would provide sufficient protein and glucose to avoid catabolism, without the risk of tipping the insulin/glucagon scale. [quote:2e9f705ae4]Thanks for your thought and research citing, Scott. [/quote:2e9f705ae4] Thanks for bringing up the question--its worthwhile to look at these things.

I am not a scientist, and it seems like the people responding to this thread are, but I thought I would jump in with a point that Gent brought up about Sears' exclusion of ketosis in his book. Actually, he doesn't exclude ketosis, but rather states that ketosis is an abnormal metobolic state for the body to be in, and this is his main critique of low-carb diets like the Atkins diet. However, Sears also states that one has access to his/her fat stores while "in the Zone" and can thereby use these fat stores for energy. My understanding is that if the body is generating energy from glucose, then the body is in gluconeogenesis. If the body generating energy from the breakdown of stored body fat, then the body is in ketosis. It seems to me that the Zone diet must rely a great deal on ketosis for people who are doing the Zone as a way to lose weight. Ketosis is the process by which fat is broken down for energy, i.e. if you're using your body fat, you're in ketosis. So I've always thought that Sears critique and dismissal of low-carb diets based on the fact that they put one's body into ketosis rang hollow as it seems that the Zone must as well (although not for weeks at a time). Sears also states 1) that excessive protein is converted into glucose in the bloodstream and 2) that people on low-carb/high-protein diets force their body to attack muscle mass in order to create needed glucose, thereby consuming muscle instead of stored fat for energy and 3) that the Zone diet offers the body enough protein so that it does not attack existing muscle mass. Now, these things also seem in contradition to each other to me. If the Zone diet is giving the body enough protein so that the body does not attack muscle mass, how can Sears state that a person on a diet with higher rations of protein will find their bodies attacking muscle mass? Doesn't make sense. If it works for one diet, it works for another. From another angle, if excessive protein consumption gets broken down into glucose, why would one's body attack muscle mass for glucose when it is deriving glucose from excessive protein consuption? If I am wrong about how the body generates energy and/or my understanding of Sears' positions, please let me know. Sonja

[quote:3d23bdfe20="sonjabean"] My understanding is that if the body is generating energy from glucose, then the body is in gluconeogenesis.[/quote:3d23bdfe20] No, in basic terms, gluconeogenesis is the production of glucose from other sources. [quote:3d23bdfe20] If the body generating energy from the breakdown of stored body fat, then the body is in ketosis. It seems to me that the Zone diet must rely a great deal on ketosis for people who are doing the Zone as a way to lose weight. Ketosis is the process by which fat is broken down for energy, i.e. if you're using your body fat, you're in ketosis. So I've always thought that Sears critique and dismissal of low-carb diets based on the fact that they put one's body into ketosis rang hollow as it seems that the Zone must as well (although not for weeks at a time).[/quote:3d23bdfe20] Fat-burning and ketosis are not the same. In the Zone, where adequate glucose is consumed, fat is fully broken down to C02 and H20. With inadequate glucose intake, fat is only partially broken down to produce ketones for use as an alternative energy source. [quote:3d23bdfe20]how can Sears state that a person on a diet with higher rations of protein will find their bodies attacking muscle mass? Doesn't make sense. If it works for one diet, it works for another. From another angle, if excessive protein consumption gets broken down into glucose, why would one's body attack muscle mass for glucose when it is deriving glucose from excessive protein consuption?[/quote:3d23bdfe20] It depends on which side of the critique you are looking at. Excess protein is not the same as inadequate carbs. The first can put undue load on the kidneys which must get rid of the ammonia byproducts, the latter can result in the use of existing LBM.

Scott, thanks for replying. I've been very curious about these questions. I would really appreciate it if you could clarify a few points, because I'm still a little confused on a few things! [quote:fe89209581] Fat-burning and ketosis are not the same. In the Zone, where adequate glucose is consumed, fat is fully broken down to C02 and H20. With inadequate glucose intake, fat is only partially broken down to produce ketones for use as an alternative energy source.[/quote:fe89209581] But isn't Sears saying that you will be using your fat as an alternative source of energy? If so, then isn't the body deriving energy from the ketones produced by the fat? Are CO2 and H2O sources of energy? [quote:fe89209581] It depends on which side of the critique you are looking at. Excess protein is not the same as inadequate carbs. The first can put undue load on the kidneys which must get rid of the ammonia byproducts, the latter can result in the use of existing LBM.[/quote:fe89209581] Doesn't a low-carb diet almost alwasy go hand-in-hand with a high-protein diet? I know there is such a thing as a "fat fast," but isn't that very rare? In other words, the risk of losing LBM in a low-carb (i.e. high-protein) diet is not any higher than a Zone diet? Thanks again. Looking forward to your responses! Sonja

You're welcome! [quote:4c038917ad] But isn't Sears saying that you will be using your fat as an alternative source of energy? If so, then isn't the body deriving energy from the ketones produced by the fat? Are CO2 and H2O sources of energy?[/quote:4c038917ad] Under most conditions the human body will always use a % of fat and % of carbohydrate for fuel--the % of fat is higher when insulin levels are controlled. Burning fat produces carbon dioxide (CO2) and water (H2O). If glucose intake is inadequate, fat is only [i:4c038917ad]partially[/i:4c038917ad] broken down to form ketones to assist in gluconeogenesis. Here is a nice write-up on the process. http://www.sun.ac.za/med_physbio/me...otnote.htm A lot of websites (both pro and anti low-carb) describe it as simply a by-product of burning fat--I don't agree with this. The question is, does producing them to an excess whereby they need to be eliminated via urine, breath etc. on a regular basis give rise to any long-term metabolic issues? [quote:4c038917ad] Doesn't a low-carb diet almost alwasy go hand-in-hand with a high-protein diet? I know there is such a thing as a "fat fast," but isn't that very rare? In other words, the risk of losing LBM in a low-carb (i.e. high-protein) diet is not any higher than a Zone diet? [/quote:4c038917ad] I think that depends on how you are defining "high protein". If one was eating 75g of protein a day and only 25g of carbs, I would consider this low-carb, but I wouldn't necessarily call it high-protein. As a % of calories, yes, but not in terms of actual protein intake. While it's likely true that you could eat a higher amount of protein to provide the raw material for the gluconeogenesis process and avoid any possible loss of LBM from inadequate carb intake, you still have the issue of eliminating nitrogenous waste by-products. Not a dietary prescription for maximizing health and longevity. The Zone is a calorie-restricted program so that you are minimizing having to eliminate any excess that your body isn't using and decreasing the amount of free-radicals in the process.

Scott--thanks again. You've been so nice to answer my questions! As you've probably guessed, I'm new to this forum and the Zone, and it makes me feel good to have an exchange with someone like you who is patient and knowledgable. So! I read the "footnote" that your link pointed me to. It was very helpful. However, I was unclear about how the break down of fat (when adequate glucose was present) translated into energy. The footnote just said that the mere fact of the two molecules splitting generated energy, but not what form the energy took nor how it was delivered to the body's cells, muslces, etc. The main article by Koeslag (from which the footnote derived) said that fat could not be converted back to glucose and that the creation of ketones was a different process. So how is fat generating energy if not creating glucose or ketones? My understanding was that these were the only two sources of energy for the body. Thanks also for you explanation on how a person on a low-carb, high-protein diet could conceivably be eating such a small amount--total--that protein intake could be insuffient to prevent lost of LBM. Again, that seems unlikely to me, as once you've cut out most carbohydrate from your diet, you're pretty much left with eating foods that are high in protein. But being in ketosis does suppress appetite, and therefore, I could see some cases where insufficient amounts of protein are consumed. Sonja

[quote:13124a95b1]As you've probably guessed, I'm new to this forum and the Zone, and it makes me feel good to have an exchange with someone like you who is patient and knowledgable. [/quote:13124a95b1] Thanks. There are a number of patient and knowledgeable people on this forum who can help! And I hope some of them chime in if I am mistaken on something or if there is disagreement! [quote:13124a95b1]However, I was unclear about how the break down of fat (when adequate glucose was present) translated into energy. The footnote just said that the mere fact of the two molecules splitting generated energy, but not what form the energy took nor how it was delivered to the body's cells, muslces, etc. The main article by Koeslag (from which the footnote derived) said that fat could not be converted back to glucose and that the creation of ketones was a different process. So how is fat generating energy if not creating glucose or ketones? My understanding was that these were the only two sources of energy for the body.[/quote:13124a95b1] Energy comes from the production of ATP. ATP can be produced from glucose, fat, amino acids... [quote:13124a95b1] Thanks also for you explanation on how a person on a low-carb, high-protein diet could conceivably be eating such a small amount--total--that protein intake could be insuffient to prevent lost of LBM. Again, that seems unlikely to me, as once you've cut out most carbohydrate from your diet, you're pretty much left with eating foods that are high in protein. But being in ketosis does suppress appetite, and therefore, I could see some cases where insufficient amounts of protein are consumed.[/quote:13124a95b1] I based my protein number on the current Zone recommendations for the average female (75g). If one is thinking calorically rather than hormonally you are right--if a person is replacing each gram of carb with a gram of protein you would be left perhaps with a diet that is high in protein both in caloric % and in absolute grams. The Zone doesn't work this way. The Zone recommends a certain amount of protein to maintain a positive nitrogen balance. With an adequate carbohydrate intake, this amount seems to come in a range between 75g - 140g based on 11-20 blocks (there are no doubt some who consume less and more blocks). If one is eating too few carbs, a catabolic state develops. Too much carbs and you run the risk of hyperinsulinemia. The Zone does not consider increasing protein intake to prevent such catabolism because that is not a long term dietary solution that will maximize health and longevity. I believe it is better to simply provide adequate glucose to begin with to prevent a high amount of gluconeogenesis in the first place.

[quote:15aca5d33e] Energy comes from the production of ATP. ATP can be produced from glucose, fat, amino acids...[/quote:15aca5d33e] I'm sorry, but I have no idea what ATP stands for! Could you spell that out for me? Then I'll look it up! I know I keep thanking you, but I just want you to know that I appreciate all your help. This really has increased my understanding of the Zone diet a great deal, and I know that for me, I need to understand something before I can really *believe* in it. Sonja

Jonjabean, at last one I know the answer to. Adenosine Tri-Phosphate. I knew that biology degree would be be useful someday!

Thanks Dave! I looked ATP up. Seems like I need to spend some time in a library if I want to really understand this process. I'm not even sure of what questions to ask next! Sonja

Hi Scott, [quote:6eed459237="Scott"] Thanks for elaborating. If ALT/AST enzymes are involved in the catabolism of protein, why would an increase in LBM be experienced? I can definitely understand why ALT/AST would increase for a higher level of physical activity who aren't adding enough fat or carbs or total blocks and are subject to muscle wasting. [/quote:6eed459237] The fact that their LBM was constant or increasing can be an indication that their dietary protein intake was more than sufficient to preserve the body mass and that probably some amount of that dietary protein (not muscle) was partially used to produce glucose. This will equally increase the ALT/AST levels. With catabolism is meant not necessarily the demolition of muscle protein but any use of protein other than for anabolic purposes. [quote:6eed459237] Its definitely worth looking at. I wonder if increasing the number of blocks as opposed to lowering the p/c ratio would be a better solution? This would provide sufficient protein and glucose to avoid catabolism, without the risk of tipping the insulin/glucagon scale. [/quote:6eed459237] Increasing the number of blocks may be a solution, but a higher than necessary amount of protein may be detrimental in the long run (kidneys, liver). This is my hunch. Thanks again for your coments.

[quote:20b1e3cff4="Scott"] Thanks for elaborating. If ALT/AST enzymes are involved in the catabolism of protein, why would an increase in LBM be experienced? [/quote:20b1e3cff4] [quote:20b1e3cff4="Gent"]The fact that their LBM was constant or increasing can be an indication that their dietary protein intake was more than sufficient to preserve the body mass and that probably some amount of that dietary protein (not muscle) was partially used to produce glucose. This will equally increase the ALT/AST levels. [/quote:20b1e3cff4] That's what I figured.