Why does Insulin Resistance Improve with Exercise?
Many of us facing diabetes or pre-diabetes have been told to improve our diets and start exercising. These two pieces of advice are directed at nearly everyone at some point in their life. Besides these tasks being challenging, the frequent use of this advice can make it seem vague or non-specific, and may therefore tend to fall on deaf ears. However, exercise has a strong influence on insulin resistance, a major risk factor for the development of Type 2 Diabetes.
First, a refresher on how your body processes digestible carbohydrates: Whether from the digestion of sugar-rich food or via the assembly from other nutrients, our bodies are fueled by sugar. Even distantly related organisms like sharks have an endocrine system that makes use of sugar and most cells rely on glucose, a type of sugar, for energy. When there is a lot of sugar, such as after a meal, the pancreas senses this and secretes a hormone called insulin. Insulin tells cells, specifically fat, liver, and muscle cells, to store sugar energy for use later.
Fat cells, not surprisingly, store sugar as fat and are the major target for insulin. Liver and muscle cells store sugar as glycogen, which is like the starches commonly found in many plant-based foods. Glycogen can rapidly be converted back into sugar, and this fast turnaround means that the liver can respond quickly if blood sugar levels fall too low. Muscle cells, on the other hand, use large amounts of energy to contract during exercise. They use stored glycogen to power this activity.
In healthy people, blood sugar levels are tightly controlled, with cells rapidly taking sugar out of the blood following a meal and releasing sugar in between meals when levels drop. But for many people, part of this equation begins to fail as more and more insulin is required to convince cells to take sugar out of the blood. This situation is called Insulin Resistance and may develop for many different reasons.
Unlike fat and liver cells, we can easily increase the activity of muscle cells – by exercising. Working muscle cells expend energy, depleting their glycogen stores. This leads the muscle cells to take up sugar to replenish these glycogen stores, a process that continues even after the exercise is over. By providing a demand for sugar, muscle cells lower blood sugar.
In time, exercise can reverse insulin resistance, as fat and liver cells become accustomed to working at lower insulin levels. So when considering how to meet your personal health goals, focusing on factors that you can control – like exercise – will set the stage for long-term health and give you the satisfaction of knowing that you are taking proactive steps to make things better.