Here showing long term low carbers getting harmful 200+ spikes after 100 grams of glucose:
http://www.jbc.org/content/83/3/747.full.pdf
But returning to OK numbers after a period of “normal” eating.
[quote]mertdawg wrote:
Here showing long term low carbers getting harmful 200+ spikes after 100 grams of glucose:
http://www.jbc.org/content/83/3/747.full.pdf
But returning to OK numbers after a period of “normal” eating.[/quote]
That actually seems to indicate the problem with a super low carb, low/moderate protien diet is a slow down in insulin production, not insulin resistance. It also indicates that higher protein with around 54 grams of carbs keeps production stimulated enough to avoid the spikes if you do then eat some carbs.
Have you seen something indicating insulin resistance? If the problem is just production, it seems like doing things like taking whey protein might stimulate production enough to avoid this.
[quote]DoubleDuce wrote:
[quote]mertdawg wrote:
Here showing long term low carbers getting harmful 200+ spikes after 100 grams of glucose:
http://www.jbc.org/content/83/3/747.full.pdf
But returning to OK numbers after a period of “normal” eating.[/quote]
That actually seems to indicate the problem with a super low carb, low/moderate protien diet is a slow down in insulin production, not insulin resistance. It also indicates that higher protein with around 54 grams of carbs keeps production stimulated enough to avoid the spikes if you do then eat some carbs.
Have you seen something indicating insulin resistance? If the problem is just production, it seems like doing things like taking whey protein might stimulate production enough to avoid this.
[/quote]
two things, yes I have read that ketogenic diets increase insulin resistance versus “basic glucose needs met by dietary glucose” ie 100-150 grams a day.
-
Very low carb does cause physiological insulin resistance, basically the body keeping blood sugar higher when dietary glucose is scarce. You can search for “physiological insulin resistance”. Most of the sites I have in mind probably can’t be linked on T-Nation.
-
Very low carbs, by increasing energy from beta oxidation, and oxidation of ketones and decreasing energy from glycolysis definitely promotes beta cell mass atrophy. The main signal of beta gell crowth and regeneration is glycolytic enzyme pieces that increase as glycolysis increases. This would apply more to ketogenic diets where glycolysis decreases, rather than low carb diets where glucose is produced from gluconeogenesis-tearing down protein. NEither one seems optimal to me.
-
When someone does a glucose tolerance test on a low carb diet (even going under 150 grams for the 3 days prior to the test), they may get a false positive for prediabetes or diabetes, say a 150 at the two hour mark. This is despite normal insulin levels being seen, although as stated before beta cells do not proliferate when little energy is coming from glycolysis (ketogenesis and high beta oxidation). So chronic very low carbing can lead to beta mass atrophy while short term low carbing can lead to physiological insulin resistance.
Here’s one take on physiological insulin resistance and low carb diets: http://high-fat-nutrition.blogspot.com/2007/10/physiological-insulin-resistance.html
Basically this one asserts that a fasting blood sugar of 115 is not bad, and certainly 99 is not, IF it is the result of a low carb diet and your HBa1C is good.
Also asserts that yes the low insulin levels trigger the insulin resistance, but the resistance is not equivalent to low insulin. It is a change in how the cell operates due to the lipid enzyme mentioned.
[quote]mertdawg wrote:
Here’s one take on physiological insulin resistance and low carb diets: Hyperlipid: Physiological insulin resistance
Basically this one asserts that a fasting blood sugar of 115 is not bad, and certainly 99 is not, IF it is the result of a low carb diet and your HBa1C is good.
Also asserts that yes the low insulin levels trigger the insulin resistance, but the resistance is not equivalent to low insulin. It is a change in how the cell operates due to the lipid enzyme mentioned.
[/quote]
HAH. Yeah I already read that one from googling. And yeah, from what I’ve been reading muscle tissue does become insulin resistant, but it seems more due to it switching over to fat metabolism. It basically sounds like the muscle gets too busy with fat to bother with carbs and it takes a couple of days for the muscle to switch back over. And your 100g of carbs a day keeps the glucose pathway active.
my question now is, does keeping that pathway open impair muscle fat usage? Are they somewhat mutually exclusive?
It does seem like it could be dangerous if you are a very low carber that frequently binges. Like skip loading or carbing up once a week. You might be getting REALLY high blood sugar levels on a regular basis.
I’m also curious if the low carb diet affects the non-insulin glucose pathways into muscle (glut 4 or whatever it’s called). So, does muscle become sugar sensitive, even if insulin resistant on low carb, after exercise. Basically if you want to go really low carb but still have a carb cheat now and again, would it be okay after a tough session or would you still be seeing 200+ blood sugar spikes?
These are all great questions. I have come to realize that there is a lot unknown still about metabolic pathway activation and supression.
I am thinking that since very low carbs reduce metabolic rate (by up to 60%) over a period of a few weeks, then the best way to use BOTH pathways is to stay in a sweet spot zone for carbs and fat, and since insulin sensitivity is HIGHEST with 100-150 grams of carbs a day then that seems to be a natural biological tendancy to use carbs and fat. Obviously you can’t fuel your day with 125 grams of carbs so you have to be burning fat.
If you take in 50% fat and 25% carbs, and then drop the carbs and drop the metabolism 60%, guess what? It looks like you are basically processing the same fat (either directly or after gluconeogenesis) and you are processing no dietary carbs! The drop in metabolism basically is a very close match to the reduction in carbs from “optimal for insulin resistance” to zero.
So it doesn’t look like to me that burning 125 grams of dietary carbs (versus near zero) reduces fat burning at all. It just adds 500 cals to your metabolic rate.
And I still think that carbing up from 25% carbs may be good on occasion. Supercompensation occurs after glycogen depletion, BUT IT SEEMS TO BE BLOCKED on very low carb diets. I remember a phenomenon that was being looked at in grad school that glycogen depleted athletes did not supercompensate as well if they just ate sugar (sucrose, glucose) or glucose polymers after being depleted because the depletion of liver glycogen prevented a lot of the carbs from going to the muscle. As a result, they got better results carbing up by carbing up the liver with fructose (which is OK if your liver glycogen is low) and THEN the muscles were more receptive to rebuilding glycogen. They would even carb up the liver 8 hours before with mostly fructose.
I?ll go ahead and add my 2 cents on metabolic rate even though it?s probably a bit off topic and I haven?t personally found much of a slow down with low carb. I’d like to hear feedback on what I think.
I would much rather have an efficient body where I eat less as long as both I still perform the way I want and I?m not going hungry.
Everyone always takes increased metabolic rate as a good thing, I don?t. Aside from there being an association between slower metabolic rate and longer life, I think there are a number of reasons slower can be better.
First, being at a higher rate means you can eat more food (presumably you can stay more satiated even when dieting by eating more). I don?t think this is true. What should matter is the balance between hunger (and it?s mechanisms) and metabolism (and it?s mechanisms). Slower metabolism can mean less hunger and less time being hungry on a diet. If you get to eat when you want and as much as you want, what does absolute quantity matter? You could probably go through and replace things that claim to ?get your rate up? with ?get your hunger up? and it would be as true. This is especially true of exercise where I think people who go to ?burn calories? are probably working up an appetite to match.
Second, less food, less money.
Third, less food needed to gain weight. I?ve always been a hard gainer and I think more hard gainers should consider this aspect.
Forth, scheduling. I like to be able to go longer without eating and without getting hungry or cranky. This can be huge if you travel a lot. A slower rate should mean longer before going catabolic without food, more stable blood sugar when not eating, est.
[quote]DoubleDuce wrote:
I?ll go ahead and add my 2 cents on metabolic rate even though it?s probably a bit off topic and I haven?t personally found much of a slow down with low carb. I’d like to hear feedback on what I think.
I would much rather have an efficient body where I eat less as long as both I still perform the way I want and I?m not going hungry.
Everyone always takes increased metabolic rate as a good thing, I don?t. Aside from there being an association between slower metabolic rate and longer life, I think there are a number of reasons slower can be better.
First, being at a higher rate means you can eat more food (presumably you can stay more satiated even when dieting by eating more). I don?t think this is true. What should matter is the balance between hunger (and it?s mechanisms) and metabolism (and it?s mechanisms). Slower metabolism can mean less hunger and less time being hungry on a diet. If you get to eat when you want and as much as you want, what does absolute quantity matter? You could probably go through and replace things that claim to ?get your rate up? with ?get your hunger up? and it would be as true. This is especially true of exercise where I think people who go to ?burn calories? are probably working up an appetite to match.
Second, less food, less money.
Third, less food needed to gain weight. I?ve always been a hard gainer and I think more hard gainers should consider this aspect.
Forth, scheduling. I like to be able to go longer without eating and without getting hungry or cranky. This can be huge if you travel a lot. A slower rate should mean longer before going catabolic without food, more stable blood sugar when not eating, est.
[/quote]
This all makes sense. My only real concern with lowered metabolic rate (and from my experience, if I go low carb my rate of burning calories drops a little by the end of the first week and a lot at the end of 4 weeks when I really need to re-carb) is that fat loss is slower on exclusively very low carbs than on moderate, or with a cycling carbs, or with one higher carb period every 3-4 weeks.
The second possible issue is that your glycogen stores will always be slightly under-loaded. There are some who believe that that prevents stretching/pumping the muscle to gain size, or that lower glycogen promotes the use of muscle for gluconeogenesis.
Third, insulin causes hypertrophy. Obviously pushing it to the point of becoming insulin resistant (more than about 150 grams a day starts to reduce sensitivity over long periods of time) is not doing you any good, but since you have the best insulin sensitivity at 20-30% carbs, then you get the most bang for your bucks from your insulin.
And fourth, again less than 20% carbs tends to raise LDL.
[quote]mertdawg wrote:
And fourth, again less than 20% carbs tends to raise LDL.[/quote]
Just to note, out of all cholesterol scores LDL is the least productive of heart disease and LDL on low carb tends to be the non-harmful big fluffy kind. But I’m curious where did you see this? I’ve seen studies showing to opposite (atkins dieters do better on LDL and other cholesterol scores than other major diets).