De-Bunking the Insulin Hypothesis - Part 1

This is part 1 of a 2 part series exploring the hormone Insulin in a bit more detail, with specific regard to how it impacts upon fat loss.

So Firstly, What is Insulin?

Insulin is a hormone that regulates the levels of sugar in your blood.  When you eat a meal, the carbohydrate in the meal is broken down into glucose (a sugar used as energy by your cells).  The glucose enters your blood.  Your pancreas senses the rising glucose and releases insulin.  Insulin allows the glucose to enter your liver, muscle, and fat cells.  Once your blood glucose starts to come back down, insulin levels come back down too.  This cycle happens throughoutthe day.  You eat a meal, glucose goes up, insulin goes up, glucose goes down, and insulin goes down.  Insulin levels are typically lowest in the early morning since it's usually been at least 8 hours after your last meal. 

As well as regulating blood sugar, insulin is also involved in several other processes: -

  • Stimulates protein synthesis (building new muscle)
  • Inhibits lipolysis (the breakdown of fat)

Why is Insulin Often Purported to be 'Bad'?

Because insulin prevents the breakdown of body fat, it is often seen as the enemy when it comes to fat loss. Because carbohydrate stimulates your body to release insulin, it has caused some people to argue that a diet high in carbohydrate will cause you to gain fat. Their reasoning, in a nutshell, goes like this: 

High Carbohydrate Diet -> High Insulin -> Increased Lipogenesis/Decreased Lipolysis -> Increased Body Fat -> Obesity

Using this same logic, they argue that a low carbohydrate diet is best for fat loss, because insulin levels are kept low.  Their logic chain goes something like this: -

Low Carbohydrate Diet -> Low Insulin -> Decreased Lipogenesis/Increased Lipolysis -> Decreased Body Fat


However, this logic is based on many myths.  Let's look at many of the myths surrounding 

insulin: -

Eating carbohydrate-rich foods such as potato will cause an increased release in insulin.

Eating carbohydrate-rich foods such as potato will cause an increased release in insulin.

MYTH: A High Carbohydrate Diet Leads to Chronically High Insulin Levels

FACT: Insulin Is Only Elevated During the Time After a Meal In Healthy Individuals  

MYTH:  Insulin Makes You Hungry

FACT:  Insulin Suppresses Appetite

MYTH:  Carbohydrate Is Singularly Responsible for Driving Insulin

FACT:  Protein Is a Potent Stimulator of Insulin Too


“The bottom line is that insulin doesn't deserve the bad reputation it's been given.  It's one of the main reasons why protein helps reduce hunger.  You will get insulin spikes even on a low-carb, high-protein diet.  Rather than worrying about insulin, you should worry about whatever diet works the best for you in regards to satiety and sustainability.” (James Krieger)


I think that last quote sums up everything in a nutshell. Providing you are a healthy body fat level, your hormonal environment shouldn’t be of any great concern. If your body fat levels are not yet consideredwithin ‘healthy’ ranges, then most of your energies should be spent on reducing these levels, which is usually done best by increasing compliance to the nutrition and training plans and optimising sleep, stress levels and recovery. The role insulin plays in the body should be of no concern if you aren’t in an energy deficit on a regular basis. 

Next week I want to delve into Insulin Resistance, what it is and why it occurs.