Insulin and Diabetes: Why Evolution Does Not Always Work in Our Favor

How carbs and insulin influence your ability to feel hungry or full

By Michael Ormsbee, PhDFlorida State University
Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily

Many hormones can play a role in your ability to store or burn fat or make you feel hungry or full. Professor Ormsbee explains how insulin helps to regulate hunger and how it can work against you.

Bottle of insulin
Insulin is a hormone produced in the pancreas by the beta cells of the islets of Langerhans. Photo By MedstockPhotos / Shutterstock

Insulin, Hormones, and Blood Sugar

Insulin is one of the more commonly known hormones due to the huge prevalence of diabetes in the United States and globally. It acts on the liver, fat tissue, and muscles, and is one of many hormones required for human growth and development. 

Insulin’s main function is to help regulate blood sugar levels. After you eat and your blood sugar begins to rise, the beta cells of your pancreas secrete insulin, which helps take glucose out of your blood and put it into the cells where it can be stored or used as energy. 

At the same time, insulin releases signals to your brain that you are fed. This can act like a satiety signal, which will help you feel full. Insulin is a storage hormone, meaning it wants to store everything.

Thus, not only does it store sugar, but it also helps you store fat. When insulin is released, it activates an enzyme called lipoprotein lipase, or LPL, which not only moves fat into fat cells for storage, but it simultaneously inhibits lipolysis, or fat breakdown. 

This process is designed so that you have a storage depot to draw energy from during times when you’re not eating. Evolutionarily speaking, human beings could not always just walk into a grocery store and buy food when they were hungry; so, it really acts as a protection or survival mechanism. 

How Carbs Impact Hunger

Insulin has another role, too—it can increase your ability to add muscle mass. This is because insulin-stimulated glucose uptake into muscle cells also enhances muscle protein synthesis by increasing the transport of amino acids into your muscles.

Thus, when insulin is released, you essentially go into storage mode rather than burning mode and turn off your ability to use fat as a fuel. Now, let’s consider this in relation to what you eat. Very high carbohydrate meals tend to raise insulin levels to the highest level. 

Additionally, the glycemic index, or the relative amount that a food raises your blood glucose level, can predict your insulin response. The higher the glycemic index of the carbohydrate, the more it will raise insulin. 

This acute rise in insulin is normal and really not a problem. Your body handles it, and then blood glucose and insulin will return to lower concentrations. 

However, if you constantly bombard your system with overloads of high carbohydrate meals, your insulin output will always be high. This means that you’re likely spending more time in fat-storing mode than you are in fat-burning mode. 

Insulin Resistance

If this pattern continues for long periods of time, you may become insulin resistant. This is when your cells don’t respond to the insulin well, so your blood sugar is not as well-controlled and your body is forced to produce more and more insulin to have the same impact on reducing your blood glucose levels.

So, yes, we need insulin and it is critical to our health and survival. However, it is best to avoid massive swings in insulin concentrations. 

Instead, aim to keep your insulin levels stable by consuming most of your carbohydrates as vegetables or whole grains. These foods tend to have lower glycemic index values, meaning they don’t raise your blood glucose very much when you eat them as compared to sweets, some breads, and juice, which all have higher glycemic index values. 

Protein and fat can also influence insulin, but not to the same extent as carbohydrates. Thus, it may be beneficial to think about building your typical meal as protein first, good quality fats and vegetables next, and then other low glycemic index carbohydrates. 

This may seem like a lot to think about, but don’t let it stress you out. Tomorrow’s article will cover the stress hormone cortisol and the many reasons why it is important to understand.

Dr. Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University.

Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his MS in Exercise Physiology from South Dakota State University and his PhD in Bioenergetics from East Carolina University.

This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.
About Kate Findley 408 Articles
Kate is a writer, novelist, and blogger living in Los Angeles. She has been writing for The Great Courses since 2017. It incorporates her two favorite things: writing and learning.