Guest Post: The Function of Insulin in Muscle Building

Guest Post by Daniel, a fitness and CrossFit coach

Before getting started, here are a few things you need to know:

  • Bulking and cutting is not seasonal. Learning how to control your insulin can help your body burn fat and build muscle every day.
  • Muscle is made of protein. In order to build muscle, your body must synthesize more protein than it catabolizes.
  • Insulin plays a part in muscle growth and the storage of muscle glycogen.
  • Too much insulin will prevent fat burning and lead to body fat storage.
  • In order to burn fat and build muscle on the same day, consume carbohydrates strategically, especially around workout time.

Understand What Insulin Does

Insulin is a growth hormone secreted by the beta cells of the pancreas. Insulin has an essential role in the metabolism of fat and carbohydrates and it has a crucial role instantly after exercising. Insulin also improves the uptake of glucose into skeletal muscle, liver, and fat cells. Additionally, insulin also plays a part in bodybuilding since it is an anabolic hormone. Besides being a fat storage/anabolic hormone, insulin also plays an important part in suppressing the appetite. However, insulin has a negative role since it contributes to the increase in unwanted fat in the body. Insulin is involved in the burning of body fat as fuel but when the level of insulin in the body is high, it prevents the use of fat as body fuel. On the other hand, when the level of insulin is low, it results in improved fat burning capacity.

Another important role of insulin is regulating a lot of body processes. Without insulin, these body processes would not be regulated. For instance, muscle protein breakdown will speed up via a process called proteolysis. The additionally circulating protein in the blood will be converted to glucose via a process called gluconeogenesis, and the final result is an increase in blood glucose (also known as hyperglycemia). Breakdown of fat (lypolysis) will also be increased resulting in too many ketones circulating in the blood. This eventually leads to ketoacidosis, which if not addressed can be fatal.

Therefore, the main role of insulin is regulating body processes and not acting as fat storage/anabolic hormone. Additionally, insulin improves the uptake of glucose into the cells and is not important to transport glucose to tissues. Glucose is transported to the cells via the transporter GLUT4. Hence, glucose can be transported to cells without insulin.

You are most likely aware of the importance of glycogen/glucose (complex/simple carbohydrates) to our general health and gym performance. After working out, insulin sensitivity is high but for glucose transportation, which GLUT4 is responsible of. Exercising is the most powerful stimulant that turns on GLUT4.

This has a function in insulin action and muscle glycogen storage. However, the more you exercise the more this effect reduces. Therefore, it is recommendable to drink a carbohydrate rich beverage immediately after working out. This is because it will play a significant role in stimulating the action of insulin and storage of muscle glycogen following an exercise. This is very advantageous since most of the calories taken in soon after an exercise move favorably to the skeletal muscle which as a result helps in better adaptation from exercising. However, it does not mean that you will lose muscle mass if you do not take in any calories after exercise. Eventually, it is the sum of calories which are consumed that takes priority over timing of nutrients.

Controlling Insulin to Gain Muscle Mass

To build muscle mass, you will need high levels of insulin all the through the day. You will especially require high insulin levels around workout time in order to take advantage of the fact that at this time, the cell membrane is extra permeable to insulin and what it is transporting such as glucose.

Controlling Insulin to Build Muscle and Lose Fat

This is one goal that most people want to achieve; however, some people have been misled into thinking that this is impossible. Traditional advice claims that one must alternate between these two goals in order to gain more muscle mass with reduced body fat. However, this is not proper advice after all.

When blood glucose is high, insulin is produced and glucose is stored in muscle glycogen or liver glycogen. When blood glucose is low, insulin production reduces and fat is used as fuel by body.

Insulin is like a switch that is controlling fat burning or building muscle. Therefore, it only takes minutes for this change to take place.

Therefore, this means that you can create a daily plan when you can burn fat and build muscle. You can also control the length of these periods to change the rate at which you build muscle and burn fat.

If you want to build muscle faster, increase the production of insulin around workout time. Insulin will not convert glucose to fat if it can be stored as muscle glycogen first. After training intensely, both muscle and liver glycogen are greatly depleted, so you do not have to worry about carbohydrates at this time.

To gain muscle even faster, consume carbohydrates one more time or two more times during the day then keep insulin levels low for the remaining part of the day to burn fat.

Author’s Bio

I am Daniel, a fitness and CrossFit coach. If you have any questions, you may reach me at where I teach people how to achieve perfect form with bodyweight exercises such as yoga and rowing, source as well as how to best utilize exercise machines like treadmills and rowers.

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