We’ve all heard of insulin, and we probably all have a pretty OK understanding of what we think it does. But do you know how insulin controls our fat loss? Here in the first part of The Hormone Series, I will delve a little into what it’s all about!
What is insulin?
Insulin is a hormone secreted by the pancreas as a reaction to high blood sugar levels. It is essentially a key that allows cells to use glucose for energy (as glycogen), or store it (as triglycerides in fat cells).
If you have more sugar in your blood than is immediately required, then insulin is released. It aids the transportation of glucose through lining of cells in order to be used as energy. When we are working out or being active our muscles and other cells require energy, so the glucose goes there. If we are sedentary and do not require the energy, then the sugar is stored in your liver, ready to be used when required and maintain a balanced blood sugar level.
When we have low blood sugar, insulin levels drop, and this causes the release of glucose from the liver. High levels of insulin in the blood inhibit glucose production by the liver, and lock fat in fat cells. We must try and keep our insulin levels low if we are to be able to use fat for fuel, and aid weight loss. But there are a few factors in our control that are working against this!
What causes my blood sugar to rise?
Carbohydrates are a source of sugar. This sugar is digested and then goes into the blood stream to be stored or used. There are different types of carbohydrates, and these have a different impact on the rate at which blood sugar increase. Carbohydrates that are higher on the glycaemic index (like white bread, white rice, potato products) spike blood glucose more rapidly. Foods that are high in sugar and low in fibre will cause a rapid spike as there is no fibre to control the rate of digestion – think about sugary drinks like soda… big, fast blood sugar spike!! (NB – fructose (sugar in fruits) is metabolised by the liver, and therefore does not require insulin to control its levels – this is for another day!).
For a while, the pancreas can handle this workload; however, over time it becomes exhausted and unable to efficiently release insulin any longer. This can result in the chronically elevated blood glucose levels found in type 2 diabetes or metabolic syndrome. At the same time, because insulin release is now inefficient, glucose is no longer being delivered to the cells that need it, resulting in cell starvation.
It’s not only what we eat that can spike blood sugar levels. Caffeine stimulates the release of adrenaline, which tells the body to release stored glucose. The same things happens when we are in a stressful situation. When we are in a constantly heightened level of stress, our blood sugar can become constantly raised, leading to hyperglycaemia.
There is also the issue of our blood sugar dropping too low, or hypoglycaemia. Typical early warning signs are feeling hungry, trembling or shakiness, and sweating. In more severe cases, you may experience brain fog and the inability to concentrate. This can happen if you go for long periods without food, but it can also happen immediately after a blood sugar spike.
When our blood sugar rises quickly (such as when we are eating high sugar foods) insulin responds rapidly and is secreted into the blood. This can then cause a negative effect, causing too much sugar to be taken from the blood and causing a blood sugar dip. These up and downs are what cause cravings of high sugar food, with our body telling us we need more energy, and fast. And also periods of hyperactivity, followed by an energy crash and an urge to nap!
How can I control my blood sugar and increase insulin sensitivity?
Insulin sensitivity is important, because when you have high insulin sensitivity, you are able to eat carbohydrates without such a large rise in the hormone. When insulin is kept low enough, fatty acids can still be released for use as energy. (See Part Two of my Fat Series, for how we burn fat).
In order to avoid the highs and lows of blood sugar caused by high sugar foods, we must aim to either eat foods that have a low sugar content, or combine foods appropriately to try and slow digestion of foods into the blood stream.
- Fibre is great at slowing the rate of digestion. Eating food high in fibre mean the rate of absorption is decreased, and blood sugar does not spike so rapidly.
- Eat foods which are low on the glycaemic index – think about complex carbohydrates such as whole grains. In a2013 editorial, Dr David Ludwig (look him up for more info!) and Dr. Walter Willett explain that “Many starchy foods, particularly highly processed grains and potato products, have a high glycemic index, raising blood glucose and insulin more rapidly than an equivalent amount of sucrose” – going on to explain that refined grain and potato products have metabolic effects comparable to those of sugar.
- Try combining macronutrients to control the effect of sugar. Adding a dose of protein and healthy fats provides sustained energy and stabilizes blood-glucose levels.
- Your insulin sensitivity is at its highest first thing in the morning, and after a workout. This is when your body has its lowest muscle and liver glycogen, and therefore will be more receptive to soak up the carbohydrates you just ate, instead of sending out large amounts of insulin to store that glucose as fat for another time. So when formulating a meal plan with a goal of improved insulin sensitivity, try placing the bulk of your carbohydrates for your first meal and the meals around your workout.
In my previous series, The Fat Series, I spoke about how resistance training can increase insulin sensitivity. Exercise can have a very beneficial role by increasing the production of human Growth Hormone, which is responsible for the release of fatty acids. Hello to burning fat for fuel! When GH is high, insulin must be low. We want to keep that environment of low insulin to encourage GH.
What is insulin resistance?
Insulin resistance (IR) is a condition in which cells fail to respond normally to the hormone. When the body produces insulin under conditions of insulin resistance, the cells are resistant to the insulin and are unable to use it as effectively. This means the sugar stays in the blood, and your blood sugar levels are elevated. Beta cells in the pancreas subsequently increase their production of insulin, further contributing to a high blood insulin level. This often remains undetected and can contribute to the development of type 2 diabetes or latent autoimmune diabetes of adults.
What causes insulin resistance?
Insulin resistance, metabolic syndrome, and prediabetes are closely related to one another and have overlapping aspects. To say that insulin resistance has a single cause would be incorrect, or at least it is unproven as yet. Rather, insulin resistance is a complex metabolic condition.
The syndrome is thought to be caused by an underlying disorder of energy utilization and storage. The cause of the syndrome is an area of ongoing medical research.
The main sign of metabolic syndrome is central obesity (also known as visceral, male-pattern or apple-shaped adiposity). That is, being overweight with adipose tissue accumulation, particularly around the waist and trunk.
When your cells are resistant to insulin, again your pancreas is overworked as the sugar is still in the blood. Once insulin gets too high, fat loss comes to a halt. People resistant to the effects of insulin will have a larger release of insulin when they eat starchy, simple carbs, and this in turn inhibits the release of fatty acids.
Higher insulin levels = more fat storage
- We want to keep our insulin levels low in order to allow our body to burn fat. This means making sure we are insulin sensitive.
- If you’re concerned, you can test your fasted blood sugar easily. It should be less than 5.6mmol/L. If it’s higher, you may have issues with insulin sensitivity, and approaching prediabetes.
- Avoid big spikes in blood sugar by eating complex carbs, healthy fats and protein.
- Stay insulin sensitive by doing resistance training.
- Be mindful to actively reduce stress levels to help maintain blood sugar.
Insulin also has a dichotomous role with another hormone, leptin, which we will look at in Part Two of The Hormone Series, next week. I look forward to seeing you then!