The following is a great series by James Krieger, founder of Weightology, that goes into great detail on what insulin is and what it actually does versus the many myths about this misunderstood hormone.
I feel sorry for insulin. Insulin has been bullied and beaten up. It has been cast as an evil hormone that should be shunned. However, insulin doesn’t deserve the treatment it has received.
Insulin: A Primer
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 throughout the 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.
Insulin doesn’t just regulate blood sugar. It has other effects as well. For example, it stimulates your muscles to build new protein (a process called protein synthesis). It also inhibits lipolysis (the breakdown of fat) and stimulates lipogenesis (the creation of fat).
It is the latter effect by which insulin has gotten its bad reputation. 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.