One of the major concerns in overall health for westerners right now is insulin resistance. This contributes to a host of problems, one of them being obesity. In this post, we’re going to talk about something you can do to improve insulin sensitivity and also your muscles’ ability to absorb glucose effectively, which in turn means that less dietary carbohydrate is stored as fat. 

So, how does insulin resistance contribute to obesity? 

Firstly, here is a brief explanation of what happens when you consume dietary carbohydrate, such as pasta, fizzy drinks or potatoes: 

  • Your liver converts the carbohydrate into an energy source - glucose 

  • When this glucose reaches the bloodstream, insulin is tasked with delivering it to various parts of the body to be used as energy, including; the liver, brain and skeletal muscle 

  • In regards to your muscles, insulin carries the glucose into them through cell insulin receptors  

  • The glucose is then converted to muscle glycogen and stored until the muscles need the energy 

  • The process is then repeated as and when the muscles use energy and require new energy supply 

This is a very efficient process, although in a lot of people the system appears to break because of poor diet and lack of exercise.  

How does this combination of lack of exercise and excess dietary carbohydrate ‘break’ the system? 

As mentioned previously, your muscles have insulin receptors that allow the passage of nutrient-containing insulin into your muscle tissue. Insulin carries the glucose (as well as a host of other nutrients) into your muscles, where it is converted to glycogen and stored for future use. An important thing to note here is that there is only a finite amount of storage room for the glucose in the human body - around 70g in the liver and around 250-400g in skeletal muscle.  

So, in order for this to work optimally, the system requires a constant turnover of energy - muscle glycogen needs to be constantly used and replaced.  

Sadly,  a for people who do not exercise regularly, diets high in carbohydrate can cause this process to ‘break’. As the muscles are already full of glycogen, they cannot accept any more carbohydrate and they therefore want to ‘stop’ the supply. The way they do this is to become insulin resistant - remember that glucose is transported into the muscles via insulin. The insulin receptors, if you like, begin to shut down so that no more glucose can flow through to the muscle. 

However, although the glucose can’t be taken up by the muscles, it has to go somewhere as it is very bad for our health if allowed to remain in the bloodstream. For most people, the only option left is that this excess glucose is converted into fat and stored in adipose tissue - unfortunately, this option comes with infinite storage space.  

This cycle continues as follows: 

  • More dietary carbohydrate is consumed 

  • The carbohydrate is converted to glucose 

  • Insulin tries to carry the glucose to the muscles 

  • The muscles reject insulin (causing insulin resistance) 

  • The only remaining option is for the glucose to be stored as fat 

  • And so forth

However, you’ll be very glad to know that there is something you can do about this: engage yourself in regular exercise, preferably of the high intensity variety. 

How does this work? 

Well, the reason that the muscles of inactive people become insulin resistant to reject glucose is that they are already stacked full of glycogen. When someone doesn’t exercise, these stores are never depleted. Therefore, the muscles do not require more energy. It makes sense then that in order to repeatedly accept glucose, the muscles must continually be drained of glycogen. The best way to do this is by exercising regularly as muscle glycogen fuels this activity. 

As you work your muscles, your glycogen stores begin to become exhausted, which means there is more space in them for new glucose. As a result, your muscles become more receptive to insulin and allow it to pass through, as follows: 

  • Dietary carbohydrate is consumed 

  • It’s then converted to glucose 

  • Insulin carries the glucose to working muscles 

  • The muscles accept the glucose as their glycogen stores are depleted through exercise 

  • Less glucose is converted to fat 

Your muscles can now be said to be insulin sensitive. This is how regular exercise can help improve insulin sensitivity and also reduce the risk of Type 2 diabetes and obesity (of course, keeping a good handle on your diet is important here too - this is a subject for an upcoming blog post).