Composed of 110 amino acids, insulin is a peptide-hormone produced within the pancreas which shuttles glucose from the blood into our cells to be burned for energy or stored as glycogen, or in the situation, we can’t store any more glycogen, it is converted into fat. But it doesn’t just help to shuttle glucose into cells, it gets protein and various other nutrients such as minerals and vitamins into our body cells to be utilised for metabolic processes. It even helps promote muscle protein synthesis, following resistance training, since it is an anabolic hormone. In fact, low levels of insulin will promote catabolism, especially of the reserve of bodyfat which is typically what people are looking to lose in this day and age. If we can learn to control our insulin levels, we can take advantage of these anabolic and catabolic responses.

Insulin – The not so good

However, insulin has some effects which aren’t very desirable such as preventing the breakdown of body fat into free fatty acids for energy production. Whilst this sounds bad, the purpose of blunting lipolysis (breakdown of fat) is so that we can use the glucose entering the bloodstream and not have it sitting in the blood where it is toxic if undealt with.

Insulin, Sugar and Modern Day Living

This is the problem with western food culture in modern day society. Everything – well, almost everything is loaded with sugar! For coping in the modern world, we do not need such copious amounts of sugar for ‘energy’. Even athletes that use up lots of energy consume far too much sugar for their own good, with endurance athletes being susceptible to prediabetes (an inability to control blood sugar within a normal range) as a result of eating a diet high in sugar and carbs. In fact, a third of Americans and a third of adults living in England are prediabetic which means it is highly likely they will go on to develop full-blown diabetes within 5 years of being diagnosed unless they act upon it.

How does Insulin respond to Sugar Overload?

So you’ve eaten a carbohydrate-heavy meal. The carbohydrates are being broken down into sugars. Your liver is already full of glycogen and so are your muscle stores. What next?

First insulin levels rise to deal with the increase in blood sugar. The increase in insulin starts to inhibit lipolysis (the breakdown of fatty acids for energy). There’s too much sugar in the blood for an ordinary spike in insulin to handle, so insulin levels spike even higher. The glucose cannot be stored in the liver or muscles, so it is converted into fat. Having chronically elevated blood sugar levels, by consistently eating too many carbohydrates and sugar causes your cells to become insulin resistant due to the chronically high levels of insulin your body produces at each meal. As a result of high sugar and insulin levels, cellular adaptations are stimulated, rendering your cells less responsive to insulin. This can suppress the signalling within these cells that occurs when insulin binds to its receptor (on the cell). Your cells become ‘insulin resistant‘. Now, in order to get the sugar out of your blood into the cells, your pancreas must secrete more insulin than normal.

Insulin Feedback Loop – determined by blood glucose levels

But that’s not the only problem. Insulin’s purpose isn’t only to get glucose out of the blood. It shuttles amino acids into muscles where it is required for protein synthesis in order to prevent muscle breakdown and help build your muscles back stronger in response to the stimulus of whatever exercise you’ve just performed. If your muscle cells are able to respond to insulin, they will receive glucose, amino acids and other minerals and the muscles will grow, helping to manage body fat. If your muscle cells are insulin resistant, then most of these nutrients will go to your fat cells.

Increasing Insulin Sensitivity and Decreasing Insulin Resistance

Due to the anabolic nature of insulin, overfat individuals tend to want to avoid spiking insulin. However, insulin is required for shuttling nutrients into various body cells and is spiked everytime you eat. The trick here is to raise insulin sensitivity in your muscle cells, hence making them more receptive to insulin and taking in glucose whilst decreasing insulin resistance in your fat cells, so that when insulin is released, lipolysis isn’t blunted as heavily.

How to Maintain High Insulin Sensitivity

  • Exercise for at least 5 hours a week
  • Participate in high-intensity training and resistance training
  • Lift weights (particularly heavy ones)
  • Fast or train fasted
  • Follow a lower carbohydrate diet
  • Consume omega-3 fatty acids, alpha-lipoic acid and chromium (broccoli is a very good source of chromium)
  • Go for a brisk walk 2 – 3 times a day, after a meal is best
  • Eat fewer carbohydrates, but not too little (I’d say 100 – 150g range)
  • Get at least 7 – 9 hours of sleep per night
  • Reduce intake of processed foods and refined sugars
  • Increase muscle mass
  • Consume more vegetables, legumes, nuts, seeds and protein

Factors Lowering Insulin Sensitivity

  • Sedentary lifestyle
  • High processed carbohydrate diets
  • Regular caffeine consumption
  • Sporadic sleep patterns
  • High stress levels
  • Nicotine use
  • Regular caffeine consumption
  • Excessive alcohol consumption

Insulin Response in Different Macronutrients

The three main macronutrients carbohydrates, fats and proteins all elicit different insulin responses. The insulin response in carbohydrates is greatest (refined carbohydrate all the more so), then proteins and finally fats. By combining fats, proteins and carbohydrates, you can decrease the spike in insulin as the consumption of all three macronutrients delays the breakdown and release of glucose into the blood. In order to reduce the spike in insulin further, it may be best to be mindful about consuming the majority of your carbohydrates at the end of a meal as one study found that this resulted in lower glucose levels and less insulin secretion.

Just because insulin increases the most when carbohydrates are eaten, doesn’t mean carbohydrates should be avoided entirely as they can help to satiate hunger. It may be best though to have slower release carbohydrates or eat carbohydrates towards the end of our meals to slow the spike in insulin. You can do this by choosing foods low on the glycemic index or low on the insulin index. The exception to this is if you’ve just finished a workout and you want that insulin high to shuttle all the nutrients you’re consuming into the body cells which need them most!

Did you know the role insulin plays in our body? Share your thoughts down below!