How much Carbs do you REALLY need?
- 07-12-2009, 11:22 PM
How much Carbs do you REALLY need?
Ok here it goes....
What seems like a basic question to most is quite complex to me. Most say that carbs are essential to fuel muscle...but from what i have studied this is a gross oversimplification that is starting to get on my nerves.
ATP fuels muscles not glycogen. Glycogen is a stored energy source that is broken down into ATP via glycolysis -> Krebs -> Electron Transport chain.
Glycogen is first broken down into glucose, converted into 2 pyruvate. In the presence of oxygen it will then be converted to acetyl CoA and in an anaerobic environment will be converted to lactic acid (like when u work out).
But lets go with the anaerobic process from acetyl CoA its further reduced until it hits the ETP(electron transport chain) as CO2, NADH, and FADH2. The net output about 34-36 ATP.
Now lets go back to the conversion of pyruvate to Acetyl CoA. Fat can be oxidized to fatty acids down to acetyl CoA and then can undergo the Krebs cycle and the ETP which produces a bulk of the 34-36 ATP. Glycolysis only yields a net ATP output of 4 ATP.
Lets take this even further in the process known as gluconeogenesis where glucose is made from pyruvate which can be derived from high levels of acetyl Coa which are converted to pyruvate so and then made into glucose to then be stored as glycogen.
So after a gross over simplification of the pathways i pose the question...why are carbs needed in diets? What are the downfalls of ketosis? Are there actually any documented studies attributed to what happens with prolonged lack of carbs? Will the lack of carbs lead to muscle atrophy if levels of fat and protein intake are sufficient (maintenance or above)?
Also if carbs are needed how much do u actually need in order to avoid possible negs of low carbs? How is carb cycling more efficient at created fat loss/muscle gain? What is the ideal period to cycle? How long should one carb cycle? etc.
Im sick and tired of over simplified answers, bull**** opinions, biases due to promoting some new diet fad to have u spend **** tons of money on their books and products and i want to get down to the science of the matter.
So to my educated peers and superiors on Anabolic Minds....please help. I really want to have some intellectual debate on this matter. I dont want this to be offensive or spark conflict....i just to start getting into the "meat and potatoes" of dieting 101
- 07-12-2009, 11:25 PM
07-12-2009, 11:32 PM
ok, but can it be anabolic with zero carbs given it can produce everything it needs in the absence of carbs? And are there any side effects of excess ketones and such due to these conversions?
07-12-2009, 11:48 PM
I've done keto diets and extended periods of no carbs but i found carb rotation worked best.
It's an energy source so work your training around your diet.
07-12-2009, 11:58 PM
The only dangers of ketones is ketoacidosis which is by-product of high blood sugar levels (from carbs) and ketones. Ketones alone are harmless and can support all bodily functions.
07-13-2009, 12:30 AM
arent ketones used for energy in the absence of carbs?
also isnt ketoacidosis found primarily in patients with out of control diabetes?
I would also like to refer to the Inuit diet void of all carbs and they actually do not suffer from many of the disease of society....(adult onset diabetes, obesity, etc). Can this be a valid example supporting your point loz that carbs are essence not needed to live a healthy life?
07-13-2009, 12:58 AM
07-13-2009, 01:00 AM
07-13-2009, 09:34 AM
You can induce ketoacidosis and not be diabetic by being in deep ketosis and being dehydrated. A lady at work is on a "keto" diet recommended by the local "fat clinic". Without proper education, she is on severly restricted calories and refuses to drink enough water during day. She was doing a spinning class and nearly fell out in the middle. She had been testing darkest purple for 2 days on keto sticks. Needless to say some water made her fell a little better.
07-13-2009, 09:47 AM
I have been on a keto diet for almost a year now, and have had ZERO side effects except FAT LOSS. You can ONLY go into ketoacidosis if you have pre-existing medical conditions or do ZERO exercise which will lead to an over build-up up of ketone bodies in the blood because they are not being burned off for energy. If you exercise even moderately you have pretty much ZERO chance of ever having an issue with ketoacidosis (acidification in the bloodstream).
07-13-2009, 11:18 AM
young sounds like her main problem was lack of water not the diet. Even if she was on a regular diet if she was drinking enough water she would have still passed out during that spin class
07-13-2009, 11:36 AM
Glucose is the obligatory energy substrate for brain and it is almost entirely oxidized to CO2 and H2O.
Numerous studies have been performed to identify molecules that could substitute for glucose as an alternative substrate for brain energy metabolism. Among the vast array of molecules tested, mannose is the only one that can sustain normal brain function in the absence of glucose (59).
Under particular conditions, such as starvation, diabetes, or in breast-fed neonates, plasma levels of the ketone bodies acetoacetate and D-3-hydroxybutyrate increase markedly (41). Under these conditions, acetoacetate and D-3-hydroxybutyrate can be used by the brain as metabolic substrates (41).
Full article here: http://www.acnp.org/g4/gn401000064/CH064.HTML
Just because the body can (arguably to some degree) function without dietary carbohydrate is not grounds for claiming that low/no carb diets are the optimal macro nutrient profile.
07-13-2009, 12:15 PM
Excellent point nitrox, allow me to provide a counter argument.
You are very right and I will not disagree with the statement that glucose is the preferred and most efficient means of providing the brain with energy. I havent completely read that amazing article you posted but i do not believe they were specific on what kind of glucose.
GLucose as i stated previously can be derived in the body by when there is an excess of Acetyl CoA and and absence of glucose. The acetyl coa with be converted to pyruvate which will then be further converted through backwards glycolysis of sorts into glucose. This will provide glucose for the brain. I believe and i can be very mistaken that this whole process is called gluconeogenesis.
I will refer again to the Inuit (eskimo) ppl of alaska where there diet composed entirely of fats and meats and they were able to function at a normal cognitive level. So their brain had to derive glucose from the high intake of fat.
Therefore the intake of glucose is not obligatory. It will by all means enhance given pathways since the body will readily use it for energy but I still do no see it as essential.
Also i pose another question....why does the intake of carbs during carb cycling allow for such dramatic results? Is it the spike in insulin? Is it the increased sensitivity allowing for rapid replenishment of muscle glycogen? What factor/factors attribute to the great success of this diet?
07-13-2009, 12:52 PM
i finally tried carb cycling a few months ago and i felt like crap and gained fat (no not water, i counted that out)
carbs give me a energy spike with a crash, fat gives me consistant energy, a little lower but at least its steady.
im 175 pounds now been as heavy as 230 and if i ate like the average joe (and didnt work out) i would be 300 something pounds.
low carb dieting for life! i love what i eat and ive been pretty consistant with it for about 9 years now.
the only mistakes ive make ive learned from, still gotta keep the cals low (which is easy to do because this diet helps fill you up) avoid cheaze and deep fried chicken wings, trans fats, and just eat enough to feel full.
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07-13-2009, 12:52 PM
07-13-2009, 12:59 PM
07-13-2009, 01:04 PM
the crash experienced by the intake of carbs....i believe and please correct me if im wrong.... is caused by a super insulin spike due to the increased carb sensitivity associated with low carb/ketosis diets.
You crash b/c your body is saying slow down i need to store all this energy before you burn it up. So you get tired and pass out.
07-13-2009, 02:04 PM
07-13-2009, 02:15 PM
Not any downfalls of a managed non-diabetic ketosis other than cholesterol levels depending on your fat sources.
There are studies of long term ketosis as it is used by doctors to treat certain children with epilepsy - ketones being used rather than glucose lowers the amount and severity of seizures. So not only will muscles not atrophy, but you can grow up on a ketogenic diet from a child.
07-13-2009, 02:49 PM
loz that makes sense. every carb up day no matter how much i slept...im gonna pass out...and let me tell you its one hell of a nap.
The biology and physiology of children is a completely different game. For the most part they have different requirements then those of post pubertal individuals. For the most past i think it is somewhat inaccurate to site that as an example.
As far as the muscle atrophy...well see that i something u will have to go into detail a little bit more. There has to be more then a lack of carbs that will cause atrophy seeing as a whole race of individuals where able to survive and be a strong hardy people. I do not believe they underwent muscle atrophy often
Also depending on the hunter gatherer society, the dependence on fruits and nuts varied. Some had a high dependence ketogenic other a low dependence. Some consumed enough fish and meat to be considered in a diet due to the fact that a majority of their calories came from fats and proteins.
07-13-2009, 04:12 PM
The body can obtain glucose from the glycerol component of fat (although from what I understand, in limited amounts) or by deaminizing protein. Since the Inuit diet also contained reasonable amounts of protein I suggest that would be the primary source of glucose.
However deaminizing protein to glucose is relatively inefficient as compared to simply taking in some carbohydrate. Fat is also a 'slow' fuel. Consequently, the longer and higher intensity your activity is the more likely a low/no carb diet is going to lead to 'side effects.'
Carb crashes come from taking in a meal with too high of glycemic load. Contributors to this are higher GI carbs, too many carbs (separating carbs and fats can be a factor in this). This is often called rebound hypoglycemia. blood glucose rises so fast that your body overcompensates with too much insulin. One the influx stops, insulin continues to push glucose below baseline which then causes lethargy and hunger.
The more insulin sensitive you are, the less insulin you need for a given meal.
What are these carb up days that you guys do? Instead of loading up on one day per week just spread them out more evenly - no crashes. IMO Carb/fat mutual exclusion is a load of horse crap.
07-13-2009, 04:37 PM
07-13-2009, 04:37 PM
The inuit diet had very high amounts of fat. Yes protein was high but ther would hae to take in around 3x the protein compared to fat in order for it to be calorically more available then fat. ( 1 g of fat = 9 calories, 1 gram of protein= 4 calories). So i disagree that they use protein as their primary fuel source.
Fat to my understand is readily converted to glucose. Why would i say this? Well if you think about it glucose and glycogen when stored to its max is converted to fat. When depleted fat is used as an energy store and is converted to glucose. So in an environment devoid of carbs it would convert the incoming fat into carbs through multiple pathways.
When you say the glycerol of the fat is used to make carbs is right to a certain degree but doesnt completely identify the pathway. The glycerol is converted to pyruvate and the fatty acid chain can be converted to acetyl CoA. Meaning there are two conversion that will yeild an energy source rather having protein undergo a costly gluconeogenesis.
Also when high levels of physical activity are present, the body will more readily use protein to rebuild damaged tissue and use the fat to be converted into an energy source.
And i am happy you have such a ferevent opinion, but from personal experience(therefore my HO), excluding fat was very detrimental to my health. On the other hand excluding a majority of carbs has actually be quite beneficial.
Another thing....a carb crash can be induced by low glycemic carbohydrates as well as high glycemic carbs. It takes less high glycemic to induce it the crash but when you have removed a large portion of carbs in your daily diet it doesnt take much for your body to respond to whatever large amount of carbs u introduce suddenly.
07-13-2009, 04:38 PM
07-13-2009, 04:44 PM
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