Ketosis and nutrient-intake

tigersword

At rest 70% of everyone's calorie burn is from fat.

So fat is the preferred fuel at rest ?

Still no. The body is constantly using both glucose and fat as energy sources. The ratio changes based on activity level. The body burns more fat at rest because fat is a slow energy source, so it allows the body to conserve glucose for when more intense activity is required. The more active you are, the more glucose is burned, and the less fat is burned, the less active, the reverse happens. It's not "preference," it's conservation.

tigersword

No. Ketones are a product of fat oxidation. Ketones don't burn fat. Fat burning creates ketones. To be honest, I'm not really sure what you're even trying to ask, because it's a question that doesn't really make sense.

I was asking if you are talking about 70% of everyone's calorie burn coming from Ketones?

And the answer to that is no, as that question doesn't make sense. It's like asking if a fire comes from the smoke. Completely backwards.

So ketones aren't fuel?

Ketones can be used in the citric acid cycle when glucose is unavailable. During normal metabolism, no, they are not fuel.

Do you have any studies (peer reviewed) to support that claim?

http://www.ncbi.nlm.nih.gov/pubmed/24706027

"Acetoacetate (AcAc) and 3-hydroxybutyrate (3HB), the two main ketone bodies of humans, are important vectors of energy transport from the liver to extrahepatic tissues, especially during fasting, when glucose supply is low."

I eat a low carb high fat diet so my normal metabolism has a low glucose supply, therefore for me and plenty of others ketones are fuel! Also anybody fasting (does that count the normal fast we all take part in between our last food of the evening and the first food the following day?), will be using ketones as fuel.

http://ajpendo.physiology.org/content/292/6/E1724.abstract?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=maratos-flier&fulltext=ketosis&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT

http://www.ncbi.nlm.nih.gov/pubmed/7554586

So you're just intentionally ignoring the part where I specified that glucose needs to be unavailable?

FYI - Unavailable is not the same as low.

I keep my glucose levels low and not unavailable. Or are you just intentionally ignoring that part.

And being at rest is not the same as being in ketosis. Which brings us back to the question you actually asked, and the answer is still no.

So what you are saying is you can be in rest and in ketosis at the same time?

lame deflect from your Low and Unavailable mix up by the way.

They are mutually exclusive. You can be in ketosis, or at rest, or both, or neither. One really has absolutely nothing to do with the other. Also, low and unavailable are essentially the same, because when glucose is unavailable the body uses gluconeogenesis to manufacture the glucose necessary from protein and fat sources. It's physically impossible for the human body to function without any glucose, whereas it is perfectly capable of functioning on 100% glucose.

tennisdude2004

At rest 70% of everyone's calorie burn is from fat.

So fat is the preferred fuel at rest ?

Still no. The body is constantly using both glucose and fat as energy sources. The ratio changes based on activity level. The body burns more fat at rest because fat is a slow energy source, so it allows the body to conserve glucose for when more intense activity is required. The more active you are, the more glucose is burned, and the less fat is burned, the less active, the reverse happens. It's not "preference," it's conservation.

So most people (especially on a fast or consuming high fat, low carbs) at rest or moving at low level activity for a majority of their day and are burning a larger ratio of ketones as fuel - so burning ketones at a higher percentage than glucose does not make it a preferred source - right nice logic.

traceywoody

I have a serious question about this - what happens if and when you resume a fully balanced diet?

tennisdude2004

No. Ketones are a product of fat oxidation. Ketones don't burn fat. Fat burning creates ketones. To be honest, I'm not really sure what you're even trying to ask, because it's a question that doesn't really make sense.

I was asking if you are talking about 70% of everyone's calorie burn coming from Ketones?

And the answer to that is no, as that question doesn't make sense. It's like asking if a fire comes from the smoke. Completely backwards.

So ketones aren't fuel?

Ketones can be used in the citric acid cycle when glucose is unavailable. During normal metabolism, no, they are not fuel.

Do you have any studies (peer reviewed) to support that claim?

http://www.ncbi.nlm.nih.gov/pubmed/24706027

"Acetoacetate (AcAc) and 3-hydroxybutyrate (3HB), the two main ketone bodies of humans, are important vectors of energy transport from the liver to extrahepatic tissues, especially during fasting, when glucose supply is low."

I eat a low carb high fat diet so my normal metabolism has a low glucose supply, therefore for me and plenty of others ketones are fuel! Also anybody fasting (does that count the normal fast we all take part in between our last food of the evening and the first food the following day?), will be using ketones as fuel.

http://ajpendo.physiology.org/content/292/6/E1724.abstract?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=maratos-flier&fulltext=ketosis&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT

http://www.ncbi.nlm.nih.gov/pubmed/7554586

So you're just intentionally ignoring the part where I specified that glucose needs to be unavailable?

FYI - Unavailable is not the same as low.

I keep my glucose levels low and not unavailable. Or are you just intentionally ignoring that part.

And being at rest is not the same as being in ketosis. Which brings us back to the question you actually asked, and the answer is still no.

So what you are saying is you can be in rest and in ketosis at the same time?

lame deflect from your Low and Unavailable mix up by the way.

They are mutually exclusive. You can be in ketosis, or at rest, or both, or neither. One really has absolutely nothing to do with the other. Also, low and unavailable are essentially the same, because when glucose is unavailable the body uses gluconeogenesis to manufacture the glucose necessary from protein and fat sources. It's physically impossible for the human body to function without any glucose, whereas it is perfectly capable of functioning on 100% glucose.

Agreed the body does absolutely need glucose, but not at the levels the typical western diet pumps in. And as you point out the body is very capable of producing glucose itself (without the need for dietary carbs).

Also the organs in our body are very adapted at running on a mix of glucose and ketones (thus reducing the requirement for glucose). At low level activity (below 75% effort - approx. - out muscles are very efficient at using ketones to fuel them).

I would question that is Glucose is the preferred fuel source for the body then why we have such a limited ability to store or produce it in sufficient quantity to run on it solely without dietary assistance.

Now ketones (converted from adipose tissue) that we all have in abundance.

tennisdude2004

I have a serious question about this - what happens if and when you resume a fully balanced diet?

Do you mean if you eat a larger volume of carbs?

If you are eating below your calorie target, your blood sugar levels will be higher, your body will produce more insulin, which in turn will help that glucose to be either burned as fuel, stored in the muscles and liver, or if consuming surplus calories converted into body fat.

mickey9694

When I resumed, I didn't gain any weight back. But I ate healthier stuff than I was before, like fruit and nuts. After a holiday or event when I ate a bunch of food, I might gain 3 or 4 lbs. but within a few days I was back to my regular weight.

yarwell

Still no. The body is constantly using both glucose and fat as energy sources. The ratio changes based on activity level. The body burns more fat at rest because fat is a slow energy source, so it allows the body to conserve glucose for when more intense activity is required. The more active you are, the more glucose is burned, and the less fat is burned, the less active, the reverse happens. It's not "preference," it's conservation.

So there is no such thing as a preferred fuel. Sorted.

http://ajcn.nutrition.org/content/70/6/1040/T3.expansion.html shows how average fuel use tends towards the dietary intake, with control subjects in a metabolic chamber getting about 55% of their daily energy from carbs and 32% from fats. Diet was 40F / 47C / 13P. Green tea extract moved the balance towards fat from carbs.

Carb eaters are carb burners and Peter Attia's n=1 showed how the substrate utilisation changes with prolonged ketosis
http://eatingacademy.com/how-a-low-carb-diet-affected-my-athletic-performance

albertabeefy

I'm really not sure what you're suggesting the difference between ketosis and burning fat for fuel is. Yes ketosis occurs when blood ketone levels are elevated, and ketone levels are elevated when the body is turning fat into ketones for use as fuel. If what you're saying about burning fat for fuel only happens once keto adapted, then anyone on a high carb diet wouldn't be able to burn off body fat and we know that isn't true so of course you don't have to be keto adapted in order to use fat stores for fuel.

The state of ketosis isn't simply elevated ketones... ketosis also causes a decrease in glucose utilization AND production. For the NON-keto-adapted individual (where their bodies prefer glucose) the body will release glucose from liver glycogen stores or produce it via gluconeogenesis. This happens less in a keto-adapted individual. Because of the decrease in breakdown of protein for energy (gluconeogenesis), keto-adaptation is also protein-sparing.

This doesn't explain why what I said is wrong. I said the body enters ketosis in a fasted state and anytime it has to use fat for fuel. This has nothing to do with fat being a preferred source of fuel.

Perhaps i misread your comment - the only thing I was correcting was the idea that ketosis happens anytime you're utilizing fat stores ... which, in hindsight, isn't exactly what you said, but it's what my brain somehow interpreted... Apologies there.

As far as being keto adapted goes, the only benefit I see to this is getting over the "keto flu" as they call it. I have seen no evidence that being keto adapted suddenly makes fat loss much more efficient than any other diet.

Protein-sparing is a huge benefit. Which is why many experts recommend it in bodybuilding circles.

For those of us that enjoy endurance athletics, being keto-adapted allows us to do hours upon hours of endurance events without popping glucose drinks/tabs/gels/bars/ constantly. Heck, I can do a sub 3hour 100km bike ride with nothing but PowerAde zero. I know keto-adapted people who do marathons with NO intake during the event. It's nice NOT bonking. The only thing I ever need glucose for is ANAEROBIC effort. (That being said, this is for us weekend warriors - elite athletes generally cannot generate world-class performances while following a low-carb/ketogenic diet, because they are always on the edge of anaerobic capacity.)

And as someone above said, when glucose is present it will always be burned first and in the absence of glucose the body has no choice but to burn fat.

Not true. The body will release glucose from glycogen stores OR catabolize protein (ie: lean mass) to create it. We know the ketogenic diet is protein-sparing. While it is true that a high carbohydrate intake can be protein sparing, it is often ignored that this same high carbohydrate also decreases the use of fat for fuel. Thus in addition to being ‘protein sparing’, carbohydrate is also ‘fat sparing’. (See Lyle McDonald, the ketogenic diet, chapter 3.)

It still needs some glucose though to burn fat.

No... The "fat burns in the flame of carbohydrate" idea is an old adage from the 19th Century ... Modern science shows that fat burns in the flame of oxaloacetate, which can be derived from either glucose or amino acids.

And I'm sorry but that last bit just doesn't make sense. You have to be keto adapted in order for your body to burn fat first and not glucose? So what if there's no glucose available but you're not "keto adapted"?

If the body NEEDS glucose (and until keto-adapted, it does need more than when keto-adapted) it will generate it via gluconeogenesis. This is what happens in fasting individuals, If glucose requirements are high but glucose availability is low -as in the initial days of fasting - the body will break down its own protein stores to produce glucose.

Are you saying the body is not going to use fat? Because that's just not true. And it doesn't really matter what the body uses first, if you are in an energy deficit you will burn body fat one way or the other.

No, I'm saying the body of a non-keto-adapted individual will burn glucose when available, manufacture it from protein (catabolization) and some fatty-acid oxidation.

If you are NOT keto-adapted, your brain is getting 100% of it's energy from glucose, as are many of your cells. If you don't have it, you MUST create it. That means the breakdown of lean tissue, because gluconeogenesis creates glucose from amino acids, NOT fatty acids.

If you can you really SHOULD read "The Ketogenic Diet" by Lyle McDonald, it covers all these topics beautifully, with all the references. It covers the history of ketogenic diets, physiology/biochemistry, various types of keto diets (standard, targeted, cyclical) and much, much more. It's an excellent read.

albertabeefy

Extended keto causes muscle loss, as well as water weight loss. That's one reason why the scale drops so quickly at first. Your body needs glucose, so when you cut carbs, your body converts the protein you eat into glucose instead of using it to maintain muscle. Carbs also regulate growth hormone and spike insulin, and insulin is one of the main hormones responsible for muscle growth and maintenance, along side HGH and IGF-1 (both also requiring carbs for proper functioning.)

Combine that with you not having any idea how much you're actually eating, and it sounds like a recipe for muscle loss.

^ and vitamin deficiency.

please consider this advice. Keto is not sustainable long-term.

Keto is absolutely sustainable long-term. I've been on it over 40 months, and I know people who've been on low-carb ketogenic diets since as long as 1998.

Keto itself does not cause muscle loss, nor a vitamin deficiency. (Though starvation or lack of nutrients will - but you don't need to be on a "keto" diet for that.)

While your body does need some glucose, from a physiological standpoint there is technically no dietary requirement for carbohydrate, as it can generate what little it needs (under 20g in a keto-adapted individual).

albertabeefy

The whole "keto adapted" phrase is really just pseudoscientific junk.

As you're obviously very biased here, and using your own opinion and bro-science instead of educating yourself with the true science behind a ketogenic diet, I'll refer you to Lyle McDonald. If you can read his book, study the references, and still argue with it logically, that's awesome. But I'm pretty sure you cannot, since it's all quite valid.

FYI, the ketogenic diet is NOT for everyone. There are limitations to it (anaerobic performance, etc.) but there are certainly those that benefit from it greatly.

To dismiss it as "psuedoscientific junk" with no science yourself backing up your claim is nonsensical. For a large percentage of the population that needs to lose weight (The obese, diabetics, those with metabolic syndrome, certain thyroid conditions, etc.) it's by-far the best diet in terms of overall fat-loss, body composition, glycemic control and markers of heart health. This according to dozens upon dozens of randomized controlled trials now.

albertabeefy

I have a serious question about this - what happens if and when you resume a fully balanced diet?

First, done properly a ketogenic diet is fully-balanced with all the nutrients one needs.

That being said, if you maintain a caloric balance (neither a surplus nor deficit) you'll gain back some water weight as your glycogen stores replenish. That's it.

*IF* you resume over-eating, you'll gain weight. The people who say "you gain all the weight back" are referring to those who over-eat when they go "off" their diet. And that's 90% of dieters REGARDLESS of the type of diet they choose.

tennisdude2004

Tiger, save your energy. He argues for the sake or arguing. Not because he has a specific stance on a subject. He debates just to debate....you'll see that soon enough

No I argue because people like you, tiger, ndj are incorrect.

I definitely have a stance.

Low carb high fat works - for some not all (in regards to sustainability). Is it healthy - yes

IIFYM and calorie counting works - for some not all ( in regards to sustainability). Is it healthy - yes

You guys seem to think that I size fits all and that's just a bit too narrow minded.

Also I tend to to enjoy debating stupid statements like - the brain only uses glucose, your body needs carbs to survive, cutting out food groups is unsustainable, no one in the world can suffer from an addiction to food Etc and many other statements made.

So whilst you guys continue to set off the derp alert, I'll continue to argue.

Besides these forums wouldn't be as much fun without opposing view points.

pennyllayne

The state of ketosis isn't simply elevated ketones... ketosis also causes a decrease in glucose utilization AND production. For the NON-keto-adapted individual (where their bodies prefer glucose) the body will release glucose from liver glycogen stores or produce it via gluconeogenesis. This happens less in a keto-adapted individual. Because of the decrease in breakdown of protein for energy (gluconeogenesis), keto-adaptation is also protein-sparing.

I'm sorry but you seem to be continuously twisting my words. I don't know if this is intentional or unintentional, but my main point was that ketosis and burning fat for fuel are essentially the same thing whereas you claimed they are not and then said something about being keto adapted and fat being the body's preferred fuel source, which I didn't even comment on.

Yes I do agree about keto diets being protein sparing, I said that in an earlier post and I also agree about it being good for endurance sports but I was referring more in terms of a fat loss diet as the OP is using it. I have seen no evidence that it makes fat loss easier than any other diet in general, but perhaps this is the case for some people. I don't see how being keto adapted is relevant to someone with very low stores of glycogen anyway. All diets cause muscle loss to some extent and high protein diets are also muscle sparing. If you could provide some studies to show that keto adapted people don't use their glycogen stores while non-keto adapted people do I'd really like to see it as to me this simply doesn't make sense. We have glycogen storage for a reason, why would our bodies bypass instant energy and go through the process of turning to fat stores? And then what happens to the stored glycogen? Are the calories just "wasted"?

Not true. The body will release glucose from glycogen stores OR catabolize protein (ie: lean mass) to create it. We know the ketogenic diet is protein-sparing. While it is true that a high carbohydrate intake can be protein sparing, it is often ignored that this same high carbohydrate also decreases the use of fat for fuel. Thus in addition to being ‘protein sparing’, carbohydrate is also ‘fat sparing’. (See Lyle McDonald, the ketogenic diet, chapter 3.)

In the context of a calorie deficit I don't see how this matters. You eat 100g of carbohydrate, you use them up through energy. Your body still needs energy to function so it turns to fat.

No... The "fat burns in the flame of carbohydrate" idea is an old adage from the 19th Century ... Modern science shows that fat burns in the flame of oxaloacetate, which can be derived from either glucose or amino acids.

I don't know what type of exercise you are referring to. Some exercise uses glucose and protein, whilst others use fat and glucose. Again, if you have any links to show that fat doesn't require glucose to be burned I'd like to see it. I am studying this subject and if my course material is wrong I should really take it up with my tutor.

If the body NEEDS glucose (and until keto-adapted, it does need more than when keto-adapted) it will generate it via gluconeogenesis. This is what happens in fasting individuals, If glucose requirements are high but glucose availability is low -as in the initial days of fasting - the body will break down its own protein stores to produce glucose.

As far as I understood it, glucose needs to not change but rather the source of glucose. The body can turn fat into glucose for use when it needs to, but obviously using protein is a faster source so it will depend what it needs it for. It is well known in the nutrition world that high intensity exercise requires glucose as it uses a different energy system to aerobic activity. So even being keto adapted is not going to help you if you do a lot of high intensity training and many athletes find their performance suffers.

No, I'm saying the body of a non-keto-adapted individual will burn glucose when available, manufacture it from protein (catabolization) and some fatty-acid oxidation.

If you are NOT keto-adapted, your brain is getting 100% of it's energy from glucose, as are many of your cells. If you don't have it, you MUST create it. That means the breakdown of lean tissue, because gluconeogenesis creates glucose from amino acids, NOT fatty acids.

If you can you really SHOULD read "The Ketogenic Diet" by Lyle McDonald, it covers all these topics beautifully, with all the references. It covers the history of ketogenic diets, physiology/biochemistry, various types of keto diets (standard, targeted, cyclical) and much, much more. It's an excellent read.

You seem to have contradicted yourself above, first saying a non-keto adapted person will create glucose from fatty acids and then later on you say they can only create glucose from amino acids. Which is it? The research I have done states fatty acids can be converted into glucose. So you seem to be suggesting that in a keto adapted person, glucose creation does not occur at all because the body no longer needs it? I do not believe this to be the case, but that rather the body creates glucose out of fatty acids when it is needed.

albertabeefy

All diets cause muscle loss to some extent and high protein diets are also muscle sparing. If you could provide some studies to show that keto adapted people don't use their glycogen stores while non-keto adapted people do I'd really like to see it as to me this simply doesn't make sense. We have glycogen storage for a reason, why would our bodies bypass instant energy and go through the process of turning to fat stores? And then what happens to the stored glycogen? Are the calories just "wasted"?

Glycogen stores are depleted on a ketogenic diet, which you must know if you're studying this.

There are not a huge amount of studies on ketogenic diets and athletic performance, but those that do find similar results: Athletes have better endurance (time to exhaustion increases) on the keto diet vs. their regular, and during low and/or medium intensity exercise, the diet is shown to actually SPARE carbohydrate stores, even though they are LOWER to begin with:

From one study (and no, not the Steve Phinney one for those who think it's biased ) :

"...adaptation to a high-fat diet would result in an enhanced resistance to fatigue and a significant sparing of endogenous carbohydrate during low to moderate intensity exercise in a relatively glycogen-depleted state and unimpaired performance during high intensity exercise..."

From another:

"The low RQ and the fact that blood glucose and muscle glycogen were maintained during exhausting exercise after 6 wk of a PSF suggest that prolonged ketosis results in an adaptation, after which lipid becomes the major metabolic fuel, and net carbohydrate utilization is markedly reduced during moderate but ultimately exhausting exercise."

http://www.jissn.com/content/1/2/7
http://www.sciencedirect.com/science/article/pii/0026049583901063
http://link.springer.com/article/10.1007/BF00392032
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC371554/?rendertype=abstract

No... The "fat burns in the flame of carbohydrate" idea is an old adage from the 19th Century ... Modern science shows that fat burns in the flame of oxaloacetate, which can be derived from either glucose or amino acids.

I don't know what type of exercise you are referring to. Some exercise uses glucose and protein, whilst others use fat and glucose. Again, if you have any links to show that fat doesn't require glucose to be burned I'd like to see it. I am studying this subject and if my course material is wrong I should really take it up with my tutor.

As mentioned previously, and supported by studies, when keto-adapted, exercise does utilize more fatty-acids for cellular respiration than it does glucose.

If the body NEEDS glucose (and until keto-adapted, it does need more than when keto-adapted) it will generate it via gluconeogenesis. This is what happens in fasting individuals, If glucose requirements are high but glucose availability is low -as in the initial days of fasting - the body will break down its own protein stores to produce glucose.

As far as I understood it, glucose needs to not change but rather the source of glucose. The body can turn fat into glucose for use when it needs to, but obviously using protein is a faster source so it will depend what it needs it for. It is well known in the nutrition world that high intensity exercise requires glucose as it uses a different energy system to aerobic activity. So even being keto adapted is not going to help you if you do a lot of high intensity training and many athletes find their performance suffers

No, the body can NOT "turn fat into glucose" . The process of gluconeogenesis wouldn't use fatty acids as substrates for gluconeogenesis. Some have theorized it's possible in very experimental conditions where dietary intake of protein was also severely deprived, but not research exists that I'm aware of. Gluconeogenesis in a healthy individual doesn't utilize fatty acids, and it's never been proven to do so. http://bioinformatics.oxfordjournals.org/content/25/1/152

As far as high-intensity exercise goes, it depends on the length and true intensity of it. I would never recommend an elite, world-class athlete could remain competitive on a LCHF diet - because that's not the case. However, for 99% of the population, those that undergo keto-adaptation find they can fuel their intense exercise extremely well using a ketogenic diet. Those doing MORE intense exercise can adopt a Targeted Ketogenic Diet and still have all the glucose required for any strength-training regimen or even any HIIT protocol Tabata has ever run. Read more on the Targeted Ketogenic Diet here: http://www.bodyrecomposition.com/fat-loss/comparing-the-diets-part-4.html

You seem to have contradicted yourself above, first saying a non-keto adapted person will create glucose from fatty acids and then later on you say they can only create glucose from amino acids. Which is it?

I've never contradicted myself - I've never stated the body can create glucose from fatty-acids, as it cannot.

The research I have done states fatty acids can be converted into glucose.

As I've pointed out above, your research has led you to an incorrect conclusion. The only way the process of gluconeogenesis can do so is using the glyoxylate cycle. And that only happens if you're a plant. I'm pretty sure I'm NOT a plant, are you?

So you seem to be suggesting that in a keto adapted person, glucose creation does not occur at all because the body no longer needs it? I do not believe this to be the case, but that rather the body creates glucose out of fatty acids when it is needed.

NO, I've never suggested glucose creation doesn't occur. I've stated it DOES occur, if needed, for the under 20g typically required by the human body if a person doesn't get it from dietary CHO intake.

But as mentioned, it cannot create it from fatty-acids. If you believe that, you are mistaken. There are no studies, texts, etc. that ever conclude or suggest human beings can or will create glucose from fatty-acids.

pennyllayne

Glycogen stores are depleted on a ketogenic diet, which you must know if you're studying this.

There are not a huge amount of studies on ketogenic diets and athletic performance, but those that do find similar results: Athletes have better endurance (time to exhaustion increases) on the keto diet vs. their regular, and during low and/or medium intensity exercise, the diet is shown to actually SPARE carbohydrate stores, even though they are LOWER to begin with:

Yes I'm aware that glycogen stores are depleted on a ketogenic diet, and this is where I'm confused about your explanation that keto adaptation makes fat the body's preferred fuel. How can you possibly know this if glycogen stores are depleted and there is no opportunity for the body to bypass the glucose? You are saying that the body would bypass glycogen but you actually haven't given any evidence that in the presence of glycogen this would be the case.

I'm well aware that low intensity exercise favours fat for fuel - that is because it's a different energy system that is used (aerobic) and it favours fat for fuel. But this doesn't prove that being keto adapted if more useful as a method of fat burning than any other diet. Let me just clarify that I don't believe the body needs carbohydrates, I'm well aware that it doesn't. I just don't believe that being keto adapted makes your body burn more fat than any other diet unless you have a medical problem.

As mentioned previously, and supported by studies, when keto-adapted, exercise does utilize more fatty-acids for cellular respiration than it does glucose.

Using more fat than glucose is not the same as using only fat and no glucose. You said the body can burn fat without glucose and I asked for some evidence of this, but what you have provided simply proves that both fat and glycogen are used but fat at a higher ratio which I don't disagree with. The studies you cited state reduced utilization of glycogen, not NO utilization.

No, the body can NOT "turn fat into glucose" . The process of gluconeogenesis wouldn't use fatty acids as substrates for gluconeogenesis. Some have theorized it's possible in very experimental conditions where dietary intake of protein was also severely deprived, but not research exists that I'm aware of. Gluconeogenesis in a healthy individual doesn't utilize fatty acids, and it's never been proven to do so. http://bioinformatics.oxfordjournals.org/content/25/1/152

As far as high-intensity exercise goes, it depends on the length and true intensity of it. I would never recommend an elite, world-class athlete could remain competitive on a LCHF diet - because that's not the case. However, for 99% of the population, those that undergo keto-adaptation find they can fuel their intense exercise extremely well using a ketogenic diet. Those doing MORE intense exercise can adopt a Targeted Ketogenic Diet and still have all the glucose required for any strength-training regimen or even any HIIT protocol Tabata has ever run. Read more on the Targeted Ketogenic Diet here: http://www.bodyrecomposition.com/fat-loss/comparing-the-diets-part-4.html

I don't agree that the body can't create glucose from fatty acids. Here's an article that explains it: http://blog.cholesterol-and-health.com/2012/01/we-really-can-make-glucose-from-fatty.html.

A lot of people doing high intensity training have a difficult time on a ketogenic diet, so I will put it down to different body types. But I would not suggest it for high intensity training as it has been shown to decrease performance in many.

As I've pointed out above, your research has led you to an incorrect conclusion. The only way the process of gluconeogenesis can do so is using the glyoxylate cycle. And that only happens if you're a plant. I'm pretty sure I'm NOT a plant, are you?

The link I provided above explains how humans create glucose from fatty acids, therefore I don't need to be a plant.

NO, I've never suggested glucose creation doesn't occur. I've stated it DOES occur, if needed, for the under 20g typically required by the human body if a person doesn't get it from dietary CHO intake.

But as mentioned, it cannot create it from fatty-acids. If you believe that, you are mistaken. There are no studies, texts, etc. that ever conclude or suggest human beings can or will create glucose from fatty-acids.

Again, I've addressed this already, but this again seems to contradict what you said before. If the body produces glucose when needed and does not have any carbohydrate to get it from then what you are saying is that it can only be created from protein and this would then suggest that a ketogenic diet would lead to more muscle loss than other diets since protein consumption is typically low too. Granted 20g is not much but that's not really the point I'm trying to make. I still don't see any evidence that glucose needs actually decrease once one becomes keto adapted. The body switches to burning more fat for fuel during aerobic exercise in everybody, but someone who hasn't adapted to this and has relied too heavily on fuelling exercise through glucose may suffer physically until they have adapted. This has no bearing on the body's need for glucose, just what it has become used to as a result of fuelling training and that is very different to burning fat as part of a weight loss plan.

I will take a look at the book you mention anyway. I'm always interested to learn more, but I think we are getting mixed up in different issues here. I have been talking in context of a weight loss plan and you are talking in terms of athletic performance which are 2 very different issues.

mickey9694

can anyone tell me if a keto diet would hurt running performance? i'm not running huge distances, about 3 miles per session a few times a week

pennyllayne

can anyone tell me if a keto diet would hurt running performance? i'm not running huge distances, about 3 miles per session a few times a week

It depends on the intensity. If you're sprinting or doing short bursts of high intensity exercise, a ketogenic diet may hurt your performance. If you're doing low intensity exercise a ketogenic diet should be fine as the body favours fat for aerobic activity. However, if you have been used to using glucose for fuelling your performance so far it may take some time for your body to adapt to the lowered amount of glucose. I wouldn't suggest jumping straight into a keto diet in the middle of training - it would be best to start during a rest period and allow your body to adapt first.

amusedmonkey

If you are worried about missing nutrients, start tracking and take a good multi.

Also for keto, your protein goal is a target. Try and hit it without exceeding. Your carb target is a limit so try not to go over. Fat is the filler to give you energy and fill up your calorie needs.

Don't listen to the doom mongers and nay sayers. Science is on your side on this. Keto/Paleo, even long term is good for you and despite the weight loss benefit, you are protected against Diabetes, Heart disease, Alzheimers etc....

Sadly you are never protected from these, some people are bound to get them no matter what they do. Please note that I'm not paranoid when it comes to low carbing - or any other kind of diet for that matter... The human body is so adaptable that living on cardboard and vitamin/mineral supplement would still be possible as long as you have enough fatty tissue to run on. That said, the same process that makes us adaptable can also be a curse, as we tend to be faulty by the means of how genetics work.

Low carb can actually be harmful for a diabetic! It's highly individualized. When I first found out I was pre-diabetic all fingers seems to point me to the very low carb diet direction, and those were the worst 3 months I ever attempted!

1. For a person who does not like the taste of meat, it is torture
2. It made my blood sugar go up and stay up at all times instead of casual spikes!

Turns out it's more complicated that that. Cortisol turns protein, both dietary and from muscle, to glucose. Being stressed about hating what I was eating did not help either!

After some experimenting, I noticed my body goes into a glucose producing overdrive any time I go under 120. My happiest carb intake seems to like to hover around 150-200. Go figure!