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Insulin – one hormone that needs some respect!

I have been getting stuck into furthering my knowledge around insulin, it gets bashed quite a lot in the fitness and nutrition world, so much that people probably fear this hormone. You hear of people saying how you should never spike insulin, or how it should only be spiked at certain times. It attracts a label as a bad hormone, that causes fat storage and all manner of scary things. As with most extreme statements I find the solution often lies somewhere in the middle. This most definitely is not going to be a “eat less carbs, reduce insulin” kind of blog…I tend to think a little deeper than that.

Using myself as an anecdotal case for a few years I regularly ate up to 6 chocolate bars per day, drank fizzy drinks and to my knowledge did not become insulin resistant. Maybe I lacked the genetic predisposition for such a diet to lead to insulin resistance, maybe it was because I was very active, maybe the rest of my diet was really good and inflammation was lower, maybe it just didn’t go on long enough, maybe I just wasn’t eating too much or had less stress….who knows?!

As you will know doubt see I have become a little interested in insulin, and really want this page to encompass much of what I have been reading lately, capture some of my current thoughts, and provide some informative reading for others.

What is Insulin?

Insulin is a hormone released by the pancreas, it has many roles within the body. All hormones are chemical messengers, exerting an influence on your bodies cells. Your cells are like roads in a city, each containing different traffic lights. Hormones turn some lights green, and others red and influence the flow and direction of traffic through the roads. Occasionally problems occur and traffic lights stop working, hormones are so powerful they will make sure traffic keeps moving by creating solutions. Of course these solutions may not be optimum and may slow down the flow and cause disruption elsewhere. Your body is like a road network and the hormones just want to keep it flowing as smoothly as possible!

What does this hormone do?

Cellular Glucose Absorption

When blood sugar rises insulin is released, this switches one of the traffic lights on muscle and fat cells called GLUT4 to green. This allows sugar to drive into the cell, thus maintaining the bodies desired blood sugar level.

Inhibits Gluconeogenesis

Gluconeogenesis basically means the creation of new glucose, the hormone glucagon aids this process. I remember it as – Gluco = glucose/ Neo = new/ Genesis = Creation. The presence of insulin stops this happening.

When glucose is in insufficient quantities in the blood stream to fuel demand on the body, your body looks to create this by other means. It uses glycogen, fats and proteins to make fuel. Glucagon is released and signals the breakdown of stored glycogen, which raises blood glucose. The body can also release glucocortisoid hormones (name given due to role in glucose metabolism) such as cortisol to increase activity of gluconeogenesis.

Now if the blood already contains enough glucose, insulin is clearly going to be released. This obviously removes the need for the body to increase blood glucose via gluconeogenesis.

Insulin role in stopping the livers contribution to blood glucose levels is likely a key factor in the overall role blood sugar management by insulin. For example if insulin output is reduced in some way, or the liver doesn’t recognise the insulin signal and therefore leaves its traffic lights on green, allowing glucose into the blood stream – we are left with elevated blood sugar levels which is not healthy for the body.

Promotes Protein Synthesis and Reduces Protein Degradation

Here is what is often missed. Protein also stimulates insulin secretion! That’s right, its not just stimulated by sugar. Proteins will turn their traffic lights on cells green, allowing amino acids (protein building blocks) to enter liver, muscle and other tissues.

Insulin sets off a cascade of traffic signals for want of a better phrase, which allows mTOR to take the driving seat. mTOR is a type of enzyme that initiates a series of reactions within the body that influence cell growth. Yep – that means muscle!

If you want to see what this looks like check out this diagram of insulin signalling. Pretty simple…urrrmmm not!

Regulates appetite

Yep that’s right, insulin has also been implicated within the regulation of appetite via its effects on the hypothalamus. The hypothalamus is part of the brain with numerous functions involving the endocrine and nervous systems. Given these functions, it influences hunger. Research seems to indicate a role for insulin along with leptin (another appetite hormone) in regulating food intake and bodyweight.

Unfortunately within the body, things can go wrong. When our systems are stretched to the limit, the body fights back. One such fight is that of insulin resistance.

Insulin resistance, what is it?

The simplistic view is that If we bombard our body with sugar which causes a release of insulin, eventually our cells will build up a resistance to its effects. In other words the traffic lights on the cells stay red so blood sugar remains high. As a result more insulin needs to be released to turn the cells traffic lights green to let sugar go from the blood into the cell, thus reaching a state of balance! We become insulin resistant. Eventually the cells that release insulin become sluggish and just can not fire enough out.

The more I learn the more I seem to ask even more questions! So does excess carbohydrate cause the insulin resistance? What about protein? Protein causes insulin release also so does this not contribute? Is it really high insulin that causes further resistance? Can we blame insulin for fat gain? Or are there lots of other things going on? Well I have been on a mission to really delve into this so lets take a look.

Does protein cause an insulin spike?

Protein most definitely raises insulin! Yep that’s right, those people saying they do not are misinformed – don’t be harsh to them, you and I were misinformed once too! Here is some cool information on beef and whey protein in the context of insulin spikes. So there has to be other factors involved in causing this state of insulin resistance. If it was just caused because insulin itself was being released, why would we not see this in people with high protein diets?

Protein (whey protein for example) may actually assist in clearing glucose from the blood through switching on more GLUT4 traffic lights! If we can assume what happens in the rats in this study also occur in humans that is.

Perhaps something else influences insulin resistance. Inflammation perhaps…

We do know that obesity is linked to insulin resistance, and in such cases inflammation promotes this insulin resistance. This is certainly an emerging area of research and it makes sense! You can read up more about the links between inflammation and diabetes here.

We know people have different tolerance levels. We all know of someone who can eat endless quantities of carbohydrates, and appears in peak health. So for their cells to continue being insulin sensitive in the presence of relatively high carbohydrate content there are clearly other influencers. I do believe that there will be genetic and historical influences that likely contribute to this sensitivity – the body is far too complex for us all to be the same!

In the context of inflammation I can say confidently as a result of my job that adjusting the carbohydrate balance of a clients diet, and getting them eating more veg has resulted in some pretty good reductions in body fat. Does a reduction in inflammation also occur? Perhaps. This report certainly suggest a reduction in inflammation through changing food choices. Fibrous foods for example have certainly been implicated in reducing inflammation, and there is also a link between diets high in fibre and a reduction in inflammatory markers.

While I am on the topic of fibre you may like to read this from the team at Precision Nutrition:

Or maybe we just eat too much?

It is not that infallible a statement to make. Whilst I am a fan of people eating as much as they can to get fat loss, this is not a green light to eat as much as you can full stop! Perhaps insulin resistance is a response to taking on board too many calories? There is data suggesting this as a contributory factor. If your cells are full and really can not take in any more glucose to store, then why would they let any in? That is what fat cells are for surely, to mop up the excess.

So we can not rule out over consumption as being a contributor. However lets clarify, 3000 calories might be too much if it is all mars bars, yet be metabolised perfectly fine in the body if it is a more mixed diet providing nutrition the body actually needs. As with anything it depends! We can not ignore the fact that fat itself has an influence on insulin resistance. Fat stored within muscle fibres can increase insulin resistance, however this does not appear to be the case with everyone. There will be an influence by rate of fat turnover, such that an endurance athlete will have very effective energy metabolism. They will have more of something called mitochondria (our cellular power stations), which will also function better. Ultimately they will use more fat. Paradoxically they will also store more fat within the muscle fibre yet not experience the insulin resistance of a sedentary person. Remember nutrition is context dependant, and there are rarely any blanket statements! This research paper explains in further detail.

Of course then comes the question – what drives over consumption? Is it the subsequent blood sugar crash that occurs as a result of insulin doing its job, shuttling the sugar into the cells? If blood sugar is low, this is a threat to survival and it makes sense that hunger hormones that signal hunger would make an appearance. The result…..more sugary foods? These foods are also crammed full of calories, yet not much in the way of essential vitamins and minerals….contributing further to increased inflammation.

Insulin resistance does not just stop at the muscle tissue, the brain is very much involved also – given that’s where our appetite regulation control centre lies (the hypothalamus). Something is happening that switches off insulin appetite signal in the brain. Tied in to this is the psychology of food marketing. Probably best not to even get into the association of sitting down to watch a film and eating a giant bag of sweets without thought…triggered by our first trip to the cinema perhaps?! Psychology is powerful, and yes what we learn by association also influences our hormonal output, which then influences our choices. This is an important recognition that is often missed! Your body is capable of anticipatory feed forward mechanisms, that means that hormones involved in digestion become trained to release as a result of environmental stimuli. This includes smell, sight and sound. There is a reason some restaurants pump our their food smells into the high street! Your body may be trickling insulin in, without having taken a bite.

There are also a number of other overconsumption theories I have heard recently in the context of blood sugar management and insulin:

1) The body does not release enough insulin to clear blood sugar (insulin resistance). This will influence hunger cues which results in more food consumption, the basic premise being that more food causes more insulin to be released which therefore opens up the cells to allow blood sugar to be stored in addition to switching off gluconeogenesis. This brings blood sugar levels back down.

2) The body will release as much insulin as needed to clear blood sugar. There is then a time delay for the body to detect the low blood sugar and kick start gluconeogenesis as insulin levels fall. During this time delay blood sugar is too low. Gluconeogenesis needs to start to bring blood sugar levels back up. It is thought this state of low blood sugar will drive more consumption of food to bring blood sugar back up.

Some people have higher baseline insulin levels, some get higher spikes, others less. It all depends!

I am sure you can see how the topic of  overconsumption is huge, and worthy of far more attention than I have given it here! However it definitely is involved in contributing to the state of insulin resistance. The questions is – does insulin resistance drive food consumption up further?!

Insulin and threats to survival

We can see that insulin is clearly vital for survival and it has many interactions with various foods (protein and carbohydrates) and states that the body may be in. The human body is incredible, its primary function is to survive. Now what happens when threats to survival occur?

Lets take starvation as an example.

We know that in times of starvation the body decreases insulin production, further to this the muscle and fat cells become resistant to the storage effects of any circulating insulin. Remember those traffic lights on the cell – the GLUT4’s – they are staying red! Why would the body do this? Well remember insulin stops gluconeogenesis, and in a time of starvation the body needs to create energy through whatever means necessary. Does it really want insulin scavenging away any circulating blood glucose which is in pretty short supply? Of course not.

Your brain wants glucose! So it wants to take any that is in short supply, it also wants to make sure glucose can be created through other mechanisms (gluconeogenesis)

When normal eating resumes your body doesn’t really know what to do with all that circulating glucose and those traffic lights on the cells stay Red. Of course this isn’t healthy for the body to be in a state of high blood sugar. Perhaps a simple solution in such circumstances is to eat a little less sugar, at least at first whilst gradually restoring insulin sensitivity.

It likely explains why starvation has been linked to the aptly named “starvation diabetes”! Even crash dieting may lead to difficulties with blood sugar management as this abstract from the Journal of Diabetes Complications indicates. While we are on the topic of crash dieting take a look at all this data indicating problems with very low calories. Cherry picked research? Maybe. Correlation or causation? Hard to tell from a summary. Interesting anyway!

Remember these responses are there for survival, and the body is an intricate system functioning off very complex biochemical pathways. We likely have different tolerance levels, different sensitivities and differing fuel demands. It is a balancing act after all, and too far in one direction or another is going to have a strong influence.

So it appears that at each end of the extreme – starvation one end, too many calories the other – that we can induce a state of insulin resistance.

I guess cortisol needs a mention too

Speaking of threats to survival without mentioning cortisol is like going into a gym and not seeing a power rack. The two just do not go together! I am not going to vilify cortisol, its essential and a vital part of survival. However if the balance tips too far in one direction, then we have problems as the body tries to fight to get back on line. Chronically elevated cortisol levels is an example of exactly that.

Cortisol is increased in times of “fight or flight”. Cortisol, as mentioned earlier is involved with the creation of glucose within the liver (gluconeogenesis). It wants glucose to be mobilised ready for action. It also causes a state of insulin resistance! Why take the risk that the glucose it needs for survival is going to get sucked back up into storage. From a survival point of view the body is doing its best! When the action is over, the body can return to normal and insulin sensitivity can resume normal business.

Then we also have the link back to inflammation, cortisol switches this off. That is awesome right!

None of this is awesome if cortisol remains elevated. It is not awesome if the body is downgrading its sensitivity to cortisol, and as a result not switching off inflammation. Remember too much of anything has consequences, some of which are less than healthy! It appears inflammation is making an appearance again.

Lets not forget sleep

With all this mention of over consumption, and stress related events contributing to our insulin sensitivity it would be naïve of me to forget sleep. Sleep is the time when we regenerate and restore, a vital process in bringing our body back to that state of homeostasis where everything functions just fine. Burn the candle at both ends and compromise sleep and the effects on appetite and insulin resistance are altered yet again. Have a read of this for an insight into the role of sleep: Sleep loss: a novel risk factor for insulin resistance and type 2 diabetes.

Perhaps our muscle fibres are responsible for our insulin sensitivity?

It is not that much of an “out there” statement, certainly having came across the paper mentioning the insulin sensitivity and muscular fat cell paradox in endurance athletes. I mentioned this earlier – endurance athletes stored more fat within the muscle, yet had better insulin sensitivity.

What muscle fibre are endurance athletes likely to be dominant on? Slow twitch, type 1 fibres.

Picture the endurance athlete build, the marathon runner for example, I wouldn’t call them fat. We have all seen this whole sprinter vs marathon runner debate, we have all seen the pictures comparing physiques, shared them to our networks and used this as justification for resistance training. People say the endurance athletes are carrying too much fat? Really?! There is a part in all of us that just knows that is utter rubbish.  Yet we all acquiesce with the fitness industry powerhouses, somewhat stroking their egos as we share their pictures and thoughts as our own. Well here I am saying “that is bollocks”.

Now lets take off the sporting comparisons and just use somatotyping descriptions. Somatotyping was originally used as a theory to associate body types with human temperament types, with each type having associated physical traits.

The ectomorph is described simply as thin, fitting the typical endurance athlete physique. They may be described as having a faster metabolism.  They will likely do better with more carbohydrates in their diet.

The mesomorph is a muscle gainer – they look athletic and carry little body fat. They have a more balanced macronutrient intake.

The endomorph could have high muscle mass alongside high fat mass. They are more inclined to have a lower carbohydrate intake.

Of course given any debate about the relevance of somatotyping you can not argue with what you see in front of you and the information you get when asking the right questions. Many people will fit these categories, however key to understanding where you lie is listening to your body!

For example if you get sluggish and tired after carbohydrates (endo/mesomorph perhaps) it may be that you just are not that sensitive to them, and fare better with them after training when the training itself increases sensitivity. If you feel energised and ready for action after carbohydrates your cells are probably like sponges sucking them up at the slightest trickle of insulin.

There is certainly some data looking into blood sugar control amongst different sports, so perhaps there could be a muscle fibre influence? The reduction in oxidative enzyme activity in muscle of type 2 diabetic patients may indicate a decline in slow twitch fibres. This adds weight to the case for fibre type, and I guess a somatotype link to insulin sensitivity. In fact more recently the journal of clinical endocrinology and metabolism provides more insight into muscle fibre types potential role in glucose regulation.

You can restore insulin sensitivity

All is not lost!

We know that exercise can restore some of the insulin sensitivity that may have been lost. Remember those GLUT4 traffic lights that are stuck on red because the body has either maxed out its insulin reserves or just never got them stimulated? Well exercise puts them on Green! Yep that’s right, we can turn those GLUT4’s on which lets blood sugar enter those muscle cells for storage. This is why nutrient timing around training can lead to very positive effects. Oh and if you engage in a solid resistance training program, any extra muscle you add will further aid removal of glucose from the blood.  We also get the added benefit of using some fat within the muscle itself, further aiding in restoration of insulin sensitivity.

Cod can also restore sensitivity, random I know but it can! Likely a result of the amino acid profile and the anti-inflammatory fats. It really just confirms what we already know about diet being used to restore sensitivity. Take this example, albeit only based on a test sample of 9, switching from their usual diet to one of lean meat, fruit, vegetables and nuts improved insulin sensitivity. We can debate whether it was because calories were reduced, inflammation was less, or just because it was paleo…..whatever the overriding factor an improvement in nutrition showed a good effect!

It is also worth a mention that carbohydrates can increase insulin sensitivity, however this must be taken in the context of what you are currently doing. If you are eating low carb, you can not suddenly ramp them right up….however it may be that gradually increasing carbohydrate consumption could have a positive effect. However you need to make sure you don’t end up eating too much overall and end up back at the start again! Another point worthy of mention is that if your still not healthy – be that through inflammation/stress – you might not get that improved sensitivity. With this is the importance of learning to listen to your own body. Remember all ducks need to be in a row really!

In one sentence you need to reduce inflammation, so eat real foods and identify strategies to reduce stress. You also need to train and get a good nights kip!


***If you are reading this and diabetic who requires insulin, and tempted to improve your lifestyle you must get a handle on your administration of insulin. Dosages may change and this is something you will have to invest some time in, or certainly discuss with your diabetes specialist as nothing on this site constitutes medical advice. I would also get in touch with other active diabetics so they can advise from their perspective how they managed their insulin doses.

***At times I may update this page as new information comes to light, so if you come across anything worthy of a mention or can link to anything please let me know or comment below! Also if you disagree with anything I have written I am cool with that, and always open to learn more and value the opportunity to look at things in another light!



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