How carbs and insulin make you fat and/or ill!

[NU_nutrition_TS]

So as not to take moto's thread any further off-topic I will continue my train of thought here.

What causes insulin secretion? Food does. Even the expectation, sight and smell of food before it even touches the lips can excite an insulin response. But when you eat food, what attributes are most related to the degree of the insulin response?

It has been shown that when administered separately, carbohydrate elicits the greatest insulin response, followed by protein, with fats trailing in last with very little insulin response. When you combine these macros - as would be the norm with real whole foods and full mixed meals - the responses can be less predictable and less consistent.

From the effect of the individual macros you would logically expect a combination of carbohydrate and fat to provoke less of an insulin response than carbohydrate alone - in other words, the minimal insulin-provoking characteristics of fat would attenuate the maximal insulin-provoking characteristics of carbohydrate. Sometimes it does but sometimes it does the opposite.

And with a combination of protein and carbohydrate you would expect a greater insulin response than with either alone. Again, sometimes you do but not always!

Another element with the insulin response of protein (or amino acids, once the protein has been digested) is that there is also a glucagon response. Glucagon is the complimentary hormone to insulin; usually what insulin stimulates glucagon blocks and vice versa.

Glucagon response is linearly associated with the rate of appearance of amino acids into the blood stream with tyrosine and methionine most closely associated with glucagon response. With insulin it was slightly different, the rate of appearance of amino acids was also associated with the insulin response but the degree of that response was much greater with the amino acids leucine, isoleucine, valine, phenylalanine and arginine. So the amino acid profile of the protein can have an effect on degree of the insulin response more so than the glucagon response.

Now compare that information with the following - lists of glucogenic amino acids, ketogenic amino acids and amino acids capable of both:

In humans, the glucogenic amino acids are:

• Glycine
• Serine
• Valine
• Histidine
• Arginine
• Cysteine
• Proline
• Alanine
• Glutamate
• Glutamine
• Aspartate
• Asparagine
• Methionine

In humans, the ketogenic amino acids are:

• leucine
• lysine

In humans, the amino acids which can be ketogenic or glucogenic are:

• threonine
• isoleucine
• phenylalanine
• tryptophan
• tyrosine

Three out of four of the amino acids that stimulate the greatest insulin response are glucogenic, as are the ones that are most associated with glucagon response, and are capable of being turned into glucose via gluconeogenesis. This makes sense if insulin's primary role is the control of serum glucose levels. But insulin switches off gluconeogenesis, so the concomitant release of glucagon counteracts this, as glucagon stimulates gluconeogenesis. So the amino acids are turned into new glucose in the liver and when released into the blood stream, the insulin helps to stimulate the uptake of that glucose into muscle and fat cells.

Insulin has a paracrine effect on glucagon so if insulin is released in the absence of glucagon - as in carbohydrate ingestion - the increasing concentration of insulin prevents glucagon from being released. So, again, the body is using these hormones primarily to control glucose levels. If there is too much exogenous glucose then we do not need gluconeogenesis making more of the stuff, so insulin clears the excess glucose and prevents the liver making its own.

However the reverse is not true. Glucagon does not inhibit the release of insulin but, in the presence of blood glucose, positively stimulates it. It seems evolution has equipped us with a very clever way of not only making our own glucose on demand but of tightly controlling the concentrations of it in the blood also with the complimentary/opposing actions of these two hormones.

It should also be born in mind that glucagon also encourages liver glycogen to be broken down into glucose again and released into the system - indeed low serum glucose is another trigger for glucagon. So, even in the absence of a protein-rich meal to furnish glucogenic amino acids, the body can draw on glucose made previously and stored by insulin.

Another oddity is that the only hormone that seems to store away excess blood glucose (whether endogenous or exogenous) is insulin but, aside from glucagon, there are many hormones designed to stimulate the release of stored glucose or other carbon sources that can then be utilised as a substrate for gluconeogenesis. These include cortisol, epinephrine and growth hormone, for example.

It would seem evolution equipped us with these many hormones to raise blood glucose because exogenous sources were not commonly available and we had to rely, instead, on making, storing and releasing our own supply using these various hormones.

All that changed with the dawn of agriculture as more and more concentrated carbohydrate sources were cultivated, grown and eaten by man. This tended to upset the balance and insulin became the hormone that ruled the roost while glucagon and the others took a back seat and only put in an appearance during times of fast, famine or 'fight or flight' emergencies when extra energy was required.

Consequently the human genome has not been equipped to cope with this chronic elevation of insulin due to increased exogenous carbohydrate intake. It causes us to retain sodium and increase blood pressure, weakens the endothelial cells in the arteries making them more susceptible to atherosclerosis and increases the likelihood that fat will be stored rather than oxidised. All bad news for long-term health.

To be continued....

[Ripped Barbarian]

Ok, but insulin sensitivity and cellular functioning are far more important in health regards.

An insulin sensitive cell can swallow glucose with ease.

It's all about maintaining insulin sensitivity and stable blood glucose, how you achieve it dosn't matter.

You can maintain insulin sensitivitiy and stable blood glucose on a high carb diet, but a doughnut and sweets diet you certainly won't. (or most of what people are eating in the UK)

End of.

[Nicholars]

Im not sure at all about low carb diets tbh, maybe some people like them but personally they make me skinny, weak and foul tempered lol carb cycling is the way to go tbh.

[cheef]

Quote

Ok, but insulin sensitivity and cellular functioning are far more important in health regards.

An insulin sensitive cell can swallow glucose with ease.

It's all about maintaining insulin sensitivity and stable blood glucose, how you achieve it dosn't matter.

You can maintain insulin sensitivitiy and stable blood glucose on a high carb diet, but a doughnut and sweets diet you certainly won't. (or most of what people are eating in the UK)

End of.

x2 why athletes eat high carbs and stay lean and healthy compared to your average couch potoato

[NU_nutrition_TS]

Well, I will answer some of those points when I continue the thread. Need time to gather my thoughts! However, I think being insulin sensitive doesn't really help with the detrimental effects of insulin and glucose in general. It's not just about the uptake and metabolism of glucose by cells...but like I said - tomorrow!

[NU_nutrition_TS]

What is high insulin?

In the post-absorptive state insulin is at basal levels (physiologically lowest levels found in 'normal' subjects) and it is pulsatile in nature, so will wax and wane slightly but not by much as it and glucagon do their thing and keep serum glucose levels stable between meals. As soon as you eat food - particularly insulinogenic carbohydrate foods - insulin levels can rise rapidly by many times above basal levels and remain elevated for up to two hours afterwards. This so it can help cells take up the excess glucose from the blood and return levels to normal.

Sometimes, when the glucose load from food is very high this insulin response can 'overshoot' and serum glucose levels fall too low causing reactive hypoglycaemia (anyone feeling 'sleepy' after a large carbohydrate meal or sugary drink/snack or very quickly craving more sweet foods have probably experienced this phenomenon).

People often think it is better to have several meals/snacks per day and so end up eating every 2-3 hours. If insulin remains elevated above basal rates for up to 2 hours after each meal then that particular individual will have insulin levels above basal rates for much of the day. This will be more pronounced if the diet is principally made up of foods that elicit the greatest insulin responses (carbohydrates for example). It also follows that glucose levels will also be elevated beyond physiologically normal levels (for a time before insulin can clear it) followed by possible hypoglycaemic dips below normal levels.

What does a high glucose level do?

Glucose is actually toxic in higher than normal (about 5 mmol/L) amounts. These are some of the major effects on cells, tissues and organs:

• It significantly reduces the phagocytic index (a measure of immune response) - a blood sugar level of just 6.6 mmol/L can reduce the phagocytic index by 75%
• It increases serum triglycerides (a marker for cardiovascular disease)
• It increases pattern A or the smaller, denser LDL particles (another marker for cardiovascular disease)
• It decreases HDL particles (thought to be a marker of protection from cardiovascular disease)
• It causes 'glycation' - the uncontrolled cross-linking between it and proteins and fats, which can be pro-inflammatory and ageing)
• It increases free radical damage (especially in the mitochondria)
• With insulin, forms the necessary alpha glycerol phosphate need to synthesis the glycerol 'backbone' to which fatty acids are attached, forming triglycerides - the storage-form in fat cells

What about high insulin levels? The major effects are:

• Causes cell proliferation (mytogenic) which can lead to endothelial damage (of the cells lining the arteries, which makes them more susceptible to atherosclerotic lesions) and also cancer
• Causes macrophages to turn into foam cells (which creates the 'fatty streaks' seen as the beginnings of an atherosclerotic leasion in arteries)
• Causes the blood to clot more readily
• Negatively affects nitric oxide synthase so less nitric oxide is produced
• Causes the excretion of vital minerals like magnesium and calcium
• Prevents lipolysis, so you don't 'burn' as much of your existing body fat
• Encourages lipogenesis - the storage of even more body fat as triglycerides

All of these factors combined can lead to increasing insulin resistance and the onset of metabolic syndrome, diabetes, stroke, heart disease and cancer as well as a greater predisposition to getting infections or suffering inflammatory conditions.

[Cyphen]

I can only sustain low carb for short periods of time, mebies 3 weeks tops, after that i feel weak hungry and worst of all bored.

Eating shouldn't be a chore, it's a vital part of being happy for me

[ATZ]

Nu, this is tiresome. Whilst this may be a diet and "health" forum, most on here are training for athletic or bb'ing purposes. In this instance a degree of carb intake is required.

Quote

Full muscule glycogen enhances myogenic gene expression,
Insulin is anabolic for a number of reasons,
The hormonal profile to a zero carb diet is catabolic for an equal number of reasons.

And before you go posted loads of example of x who did y on low CHO diet, have you actually tried maintaining athletic performance or training loads YOURSELF while low carb or ketogenic? All this postulating you do is very well, but it means little in the real world.

[CosmicFish]

Quote

Nu, this is tiresome. Whilst this may be a diet and "health" forum, most on here are training for athletic or bb'ing purposes. In this instance a degree of carb intake is required.



And before you go posted loads of example of x who did y on low CHO diet, have you actually tried maintaining athletic performance or training loads YOURSELF while low carb or ketogenic? All this postulating you do is very well, but it means little in the real world.

Speaking for myself, most times Nu posts something I learn something new. It's useful to learn about the health aspects of our diets as well as how to use them for weight training. One of my goals is to be big and strong, but another is to still be healthy at 100.

[NU_nutrition_TS]

@ATZ: DId that quote come from Lyle McDonald's website again?!

Why not say X did Y on Z? How is any less valid than If I'd done it? For all you know I might very well be a figment of someone else's imagination, who posts here on my behalf, and who eats a high carb diet but just likes to be confrontational!

I've posted a fair few examples of people that maintain an athletic lifestyle on a low or zero carb diet...you can check them out a lot better than you could ever confirm anything I ever said about my own athletic prowess!