Firstly let me apologise for the length of time it has taken to write this post and the length of the post itself but due to the huge importance of insulin in the body this was not one to skimp on. I’ll break it down into the basics of what insulin is and how it works and then later on in this post I will try and go a bit more I depth for those of you that want to learn how to maximise knowledge on insulin and how to use it to your advantage like I do.
Insulin is the centre of the universe in terms of hormones for health, weight loss and muscle gain and people hear all about it on Atkins/low carb diets but who truly understands what it is and how it works. Is it always best to keep it as low as possible, do we want spikes in insulin sometimes or is there a happy middle ground?
What is it?
Insulin is a hormone produced in the pancreas and its basic role in the human body is as a key to open cell walls for nutrients to enter cells. It is not very specific in what it affects and so will open the cell wall in muscle, liver and fat cells allowing in the glucose in the blood stream to be stored along with other nutrients and fat. When controlled this is an extremely beneficial process as we should be burning the glycogen in our muscles and liver which then need to be replenished and producing some insulin when we eat lets us top our stores back up. However with too much insulin there can be extremely detrimental effects.
How can it go wrong?
Insulin production is directly proportional to the amount of glucose in the bloodstream. Prolonged excessive glucose levels in the bloodstream is toxic and so the body needs to get it stored as fast as possible and the most dense source of glucose is carbohydrate. This means that when we eat high levels of carbohydrate (especially simple carbs like sugar which spike insulin production even more) the high insulin levels that are produced encourage storage of all this excess glucose.
This is ok if we have low levels of glycogen stored and need to replenish the stores but our muscles and liver combined only store roughly 400 grams of carbs at any one time. If you consider that an average day in western society could be cereal and toast followed by a muffin and late mid morning, a sandwich at lunch and then stir fry with noodles for tea and possibly a dessert. This can give us over 400 grams of carbs in one day and even if your exercising you very rarely deplete the stored glycogen by more than 50%. So what happens to the excess glucose?
It gets converted into triglycerides that are then stored as fat and on top of this, the fat that you ate from your last meal also gets stored giving a double weight gain whammy and there’s a cherry to go on top of this lipid storing insulin cake. The presence of high insulin levels in the blood actually prevents the body from releasing stored fat as energy by inhibiting lipase, which is the enzyme that breaks down fat. When your body then quickly stores all of this glucose in the fat cells and blood blood sugar levels drop, we get hungry again, eat again, spike insulin again and if we haven’t exercised to burn any glycogen in the muscles/liver then this next meal gets stored straight as fat and the process starts again.
As we only have a finite number of fat cells eventually these too can get filled to our maximum capacity which causes chaos to our body and this will be discussed in the geekfest at the end of this article.
What is insulin sensitivity/resistance
So we hear a lot about insulin resistance and insulin sensitivity so what are they? Well when we have constant high levels of insulin in our bodies due to eating a lot of carbs/sugar, our bodies become so used to these high levels that the cells of the muscle and liver don’t respond to normal levels of insulin as they are always full of glycogen and don’t need anymore. This is called insulin resistance. When you initially become insulin resistant this will mean that excess glucose will be sent straight to the fat cells for storage as discussed earlier until these to become insulin resistant which then leaves us with high levels of insulin and high levels of glucose floating in the bloodstream which is very bad for the body. If we also become insulin resistant the pancreas recognises that blood glucose is still too high and releases more insulin increasing our insulin resistance.
The opposite of this is becoming insulin sensitive which means that your muscle and liver cells respond well to insulin and will absorb all the glucose it possibly can in the presence of insulin before sending excess to fat cells. This is best achieved by keeping low resting levels of insulin and not creating too many insulin spikes, and by exercising in a way that depletes some of the stored glycogen so it needs to be restored. This is done with hard work such as weightlifting that is heavy for you and short/hard cardio sessions like sprints. These require the stored glycogen to be utilised where a long run burns predominantly fat and not much stored glycogen.
Is insulin ever good?
Yes. Insulin is a naturally produced hormone that is designed to create homeostasis for the body. Without it we wouldn’t store the glucose of fat that we need to survive. We can also use our knowledge of its storage role for maximal muscle growth (which will be discussed in a blog post of carb cycling/carb backloading). However what we need to understand from the science is that it responds too strongly to high carbohydrate and high sugar foods for these to be a major part of a healthy diet and need to be regulated to regulate insulin production.
It is useful to know on a very basic level that there are some organs in the body for which glucose is necessary. The nervous system needs glucose to function as does the brain which leads to a common myth that we need to eat sugar. In fact the nervous system uses so little that a minor intake even irregularly is enough to sustain them and the brain can adapt to predominantly run on ketones that are produced on a low carb diet. Ketones will be explored in a other post. The body can also convert protein into glucose if its needed. This is another reason that we don’t need to constantly need to be eating carbs for energy as long as we eat a reasonable amount of protein. This is where the idea that you break down muscles if you don’t eat regularly comes from but you will only be eating your muscle tissue if you are not eating enough protein. Insulin production will be enough when eating protein and fats to store them in the muscles without raising the levels enough to produce insulin resistance. You are more sensitive to in the mornings and less sensitive in the evenings meaning that you are going to experience more of a spike and store more of what you eat by having carbs in the morning which is why it is best to save any carbs you do want to eat till later in the day.
I will discuss some more parts below if you want to know more about what I found about the biochemistry and physiology of insulin but if you only want to understand the basics for health then just read this recap:
1) Insulin causes storage of glucose predominantly but also storage of fat
2) It will first fill up muscles and liver with glucose before storing it in fat cells
3) If there is never any space in the liver/muscles it will store more and more fat and produce more insulin leading to insulin resistance
4) The way to promote insulin sensitivity is too eat a diet low in glucose such as processed carbohydrates and sugar and to limit natural carbs such as potatoes unless its after the correct sort of exercise.
5) The correct sort of exercise is lifting weights that are heavy for you and doing short but intense cardio sessions
Continue reading for more a more in depth look at the development of type 2 diabetes, why muscle breakdown can occur with insulin resistance, the inflammatory properties of insulin, the short term affects of high insulin production, ways we can control insulin levels and finally further uses for insulin in the body.
First lets look at the short term effect of a high insulin producing meal, e.g. your mid morning muffin and latte. This food gives you a high blood glucose level which originally makes you feel really good and giving you a lot of energy. However as we have discussed as this is toxic to the body to have it in the blood the pancreas dumps a load of insulin due to the high levels of glucose to store it. This rapid storage of the glucose (be it to muscle or fat cells) causes that well known ‘sugar crash’ when there is suddenly no more glucose left in the blood stream. As a lot of peoples bodies are constantly eating high carbohydrate food their bodies and especially their brains rely on the glucose for energy as their body hasn’t adapted to use anything else (such as fat or ketones) for daily activities. This leads to grumpiness, tiredness and the classic shakes until you eat something else sugary which gives you a boost again, you get another dump of insulin and it runs in a vicious cycle.
A more in depth look at the sugar crash reveals even more problems, when the body first loses all its blood glucose it perceives this as stressful and releases adrenaline and cortisol in response. The cortisol then breaks down your muscles and takes the them to the liver where, by a complicated process called gluconeogenesis, converts them into glucose for energy, producing yet more insulin and more storage. On top of this when you have the insulin and cortisol together this encourages the storage of fat so your losing muscle and getting fatter! This also happens when we become insulin resistant as after the continued abuse of the way insulin works, when the liver cannot absorb the glucose from the blood stream due to the resistance it believes it is starved of glucose, breaks down more muscle for even more glucose. At the same time because the muscles are also resistant and so cannot absorb the glucose, this also means they cannot absorb amino acids as insulin is important for transferring these across too and so muscles get broken down and they cannot build back up. In short in terms of looks, high insulin levels are very bad.
This is what eventually leads to type 2 diabetes. We now know that due to permanent high levels of insulin the muscles/liver cant absorb more glucose as they become resistant to it so it is sent straight to fat cells until the fat cells are full to maximum capacity. The body thinks if that amount of insulin is not enough then more will help but due to everywhere being totally full we are left with high levels of toxic glucose in the blood, together with high levels of insulin. This creates Advanced Glycation End Products (AGE’s) which is where the excess glucose binds with important proteins in the blood making them useless. This creates inflammation in the blood stream and heart and neuropathies which are recognisable in type 2 diabetics as the pins and needles/numbness they often get in extremities. The Pancreatic beta cells (which make the insulin) are constantly trying to produce more and more insulin to counteract this until eventually they give up and stop working giving a very similar response to type 1 diabetics who do not produce enough insulin and need to inject it. Much of the information here is from reading material by Mark Sisson and I would highly advise his book, ‘The Primal Blueprint’ if you want to know more.
Finally in terms of health lets look at the effect of long term high levels of insulin. Insulin itself is very pro inflammatory (especially when mixed with other hormones like cortisol). It is a major part of atherosclerosis where it encourages cells to stick together and white blood cells to convert into foam cells that then suck up fat and stick to the blood vessel walls. This shows that it is not the fat itself that causes heart attacks and strokes but it is the insulin that causes them to stick. The insulin also makes the blood thicker by getting it to stick together and makes cell walls harder by reducing levels of nitric oxide that relax them all making it harder for the blood to get through any fat lined blood cells.
There are ways that are known to help blunt the insulin spike post meal. The most common of these is to consume a small amount of healthy fats either before or with a meal that might spike insulin such a small handful of almonds or some good quality butter etc. Cinnamon has also been shown to help reduce this spike and increase insulin sensitivity in humans and although this has the most evidence (and is probably the tastiest, there is also evidence of insulin sensitivity benefits from turmeric, bay leaves and cloves. Tim Ferris also reports in his book ‘The Four Hour Body’ that he found that citrus fruit such as lemon juice or a small amount of fructose (he uses a glass of grapefruit juice) before consuming high amounts of processed sugar and carbs helped blunt his insulin response on his cheat days. Finally is the good old cure all of some high intensity exercise which also has a good effect on insulin sensitivity and response. It is very interesting though that in the short term during intense exercise, because the stored glycogen is the main form of energy used, the body ‘up regulates’ glucose production and utilisation from the muscles (makes more and uses it better) which in turn gives a rise in insulin for 30-60 minutes post exercise. This is worth exploring for muscle growth and possibly not needing huge amount of carbs to spike insulin post workout at a later date. It is also well worth noting that prolonged low intensity exercise had the opposite effect of blunting glucagon (the opposite to insulin) and human growth hormone (needed to build muscle).
The time of day also plays a major part of insulin sensitivity and resistance. John Kiefer, the author of ‘Carb Backloading’ and ‘Carb Nite’ protocols discusses this at length and I will do a full post in the near future on these. The basics of it though is that you are more sensitive to insulin in the mornings and more resistant in the evenings. This gives you two ways to look at when it would be best to incorporate carbs into your diet if you are going to at all. In the morning with insulin being a lot more sensitive you are better adapted to deal with higher levels of glucose and store it in the correct place, however as we know if you have not got any depleted glycogen at that time this storage will be in fat cells, plus the presence of high insulin and cortisol (a hormone that is in abundance high in the morning as it wakes you up) encourages the storage of fat. Plus if insulin stays high from your mornings breakfast (depending on what you had) this will encourage your fat cells to retain the fat until insulin levels drop preventing fat burning for a good portion of your day. If you have the carbs later in the evening when your body is more insulin resistant you are going to find it harder to store the glucose that you do consume in the muscles and liver meaning that it potentially goes into fat storage straight away. There are a host of other hormone responses from IGF1 and HGH in the evening and these can be manipulated but exercise which is why I will cover all this in another post. Essentially just understand that that morning = sensitive, evening = resistant and as knowledge grows we can establish if and when you would prefer to increase insulin.
From everything I have found from reading around insulin so far I have a few takeaway messages for myself and it’s up to you whether your conclusions are the same as mine. High levels of insulin, especially if prolonged are extremely bad for the body leading to insulin resistance which leads to fat gain and muscle breakdown and eventually type 2 diabetes. The ways to prevent this is to keep relatively low but stable levels of insulin. This is achievable by eating a diet that is low in carbohydrates such as paleo/ketogenic/atkins or dukan style diets. I am not saying that all these are healthy as I am yet to investigate all the other sides but from a purely insulin perspective they make sense. There are times when insulin spiking may be beneficial as with exercise you deplete stored glycogen and need to replace this and timings in the morning or evening can also play a part in this but you don’t want to keep insulin raised for too long. If you are going to do this it is worth knowing that High GI foods such as sugar, bread etc will spike insulin high in a shorter period of time but then drop it in a much shorter period of time where low GI like brown rice will make it rise and fall more slowly which will become important when we learn more about carb timing. Personally, until I research something which says otherwise I’m going to endeavour to keep my insulin down with a low carbohydrate diet with the exception of a small amount after really intense exercise just to replace some of the lost glycogen (and to let me give in the my penchant, honey).
Future related blogs that will help tie in the body systems that include insulin will be:
Protein and its breakdown in a lack of carbohydrates