A Practical Primer On Insulin

Insulin management is a hot topic in nutrition and exercise these days.  There is actually a rising school of thought theorizing that insulin control is far more important than calorie consumption for weight change.  That said, most people don’t have the slightest idea what insulin is or what it does.  Let’s fix that.

Insulin is a hormone – a chemical signal sent between cells in the body.  Specifically, insulin is a storage hormone.  It promotes the storage of nutrients in the cells of the body.

Insulin Basics
When you eat food, your body breaks it down to simple chemicals that are absorbed into the blood stream.  The most important of those chemicals for this discussion is glucose, a very simple carbohydrate (sugar) that serves as the most common fuel source for your cells.  After a meal, your blood levels of glucose rise as food is digested and absorbed.  In response to this rise in blood glucose, insulin is released.  Insulin signals your cells to uptake glucose from the blood for use and storage.  In normal circumstances, this brings blood glucose back down to normal levels and gets your cells the fuel they need.

We, as physique and health conscious individuals, like it when muscle cells uptake a lot of nutrients.  We need them for cellular energy, recovery from exercise, and muscle growth.  We don’t like it so much when we store nutrients in fat cells, for obvious reasons.  So, how can be best manage insulin in order to get nutrients where we want them (muscle cells)?  By leveraging insulin sensitivity.  Cells that are highly insulin sensitive require only a small amount of insulin to uptake a lot of nutrients.  Cells that are not so sensitive to insulin display insulin resistance.  They require a lot of insulin to uptake nutrients.  Insulin sensitivity is not fixed; it’s affected by time of day, exercise, nutritional habits, and supplementation.

Promoting Insulin Sensitivity
There are several ways to increase the insulin sensitivity of our muscles (which I will refer to as just “insulin sensitivity” henceforth).

First, and most importantly, is nutrition.  Controlling the amount, type, and timing of carbohydrate consumption is critical to maintaining high insulin sensitivity.  Ingesting large amounts of simple, fast-digesting carbohydrates (sweets, soda, bread, rice, pasta, potatoes, etc) causes blood glucose levels to spike very quickly, which results in an equally large spike in insulin.  Chronic elevation of insulin, resulting from regular consumption of simple carbs, causes your cells (particularly muscle cells) to stop responding to it – they become insulin resistant.  It is through this very mechanism that Type II diabetes often arises.  Thus, a diet to promote insulin sensitivity is low-to-moderate in carbohydrate content, and gets most of its carbohydrates from slow-digesting carbohydrates like vegetables, fruits, and perhaps the occasional whole grain.

Another is through exercise.  High intensity exercise raises your insulin sensitivity both specifically and chronically.  In the short term, your muscles are highly sensitive to insulin in the hour or two directly after intense exercise, particularly weight training.  In the longer term, exercising regularly with high intensity, with both weight training and cardiovascular training, tends to elevate your insulin sensitivity full time.

The last way (OK, just the last I’m going to cover) to elevate your insulin sensitivity is through supplementation with Omega-3 fatty acids.  High doses of a quality fish oil (6-10 grams or 1 gram per % body fat daily) are often recommended for this purpose.


Nutrient Timing

Insulin sensitivity is cyclical during the day.  Thus, there tend to be specific times of day when higher levels of insulin can be beneficial for your fitness and physique.  As I mentioned, during the hour directly after exercise, your muscles tend to be primed for nutrients and are, as a result, highly insulin sensitive.  Thus, having a higher-carbohydrate meal after exercise can be a great idea, provided it is also high in protein.  The insulin spike caused by the carbohydrate content will be well tolerated by the highly sensitive muscles, and as a result, the carbs and proteins from the meal will get shuttled directly where you need them – the muscles.

Insulin sensitivity also tends to be higher first thing in the morning, when your muscles are nutrient-depleted after fasting all night.  Thus, your first meal of the day is a good time to have a higher carbohydrate content.  The carb content of your meals should fall after the first and be at its lowest in the afternoon and evening (unless you have a workout in there – see above).
Obviously, this was only a brief overview of an extremely complicated system of interactions, but  hopefully it has helped you understand all of the insulin talk and given context to some common dietary discussions.