Insulin and Muscle Building
Before we jump to conclusions and assume all insulin is bad we need to take a step back. Insulin itself is not bad; it is insulin resistance that is the problem. Insulin is key to feeding our cells and it is essential to get amino acids into tissues to provide fuel for muscle growth.
In other words, for body change you need enough insulin to build muscle, but not so much to store fat. Rather than simply trying to bring insulin to extremely low levels and possibly losing muscle in the process, it is far better to maximize insulin sensitivity.
The best way to maximize insulin sensitivity is through exercise. An August 2010 review in the American Journal of Physiology, Endocrinology and Metabolism points to muscle contraction as an insulin independent mechanism to move glucose into the cells.
Muscle contractions increase the number of glucose receptors on the cell surfaces. This is important because these receptors are down regulated in insulin resistance. Through contraction induced mechanisms the cell can get fed, increase its glycogen storage and retain or even gain muscle.
Putting it Together
While a whole book could be written on insulin metabolism, hopefully you are getting the picture that lowering insulin is not as smart as maximizing insulin sensitivity. In fact, simply having low insulin levels does not guarantee you will remain insulin sensitive.
A 2006 study in the Journal of Cardiometabolic Syndrome showed the amount of muscle on an individual determines 40 percent of his or her insulin sensitivity and 70-90 percent of blood glucose clearance. This means restoring insulin sensitivity has everything to do with contractions strong enough to induce muscle growth.
A study in the February 2008 issue of Cell Metabolism shows that hypertrophy of type IIb muscle fibers has substantial and indirect effects on liver glucose metabolism. In this study it was shown that growth of type IIb muscle was able to adjust the expression of 800 or so genes responsible for insulin sensitivity.
Adding to this carbohydrate timing to coincide with times of increased glucose removal capabilities is key. First thing in the morning after an overnight fast and within one hour after a weight training workout are times when the body can most handle and use carbs.
Insulin metabolism is a key determinant of the success of athletes, trainers and fitness enthusiasts alike. Knowing the science of insulin and how best to maximize insulin sensitivity allows for increased fitness, fat loss and health.