There is only really one way to reverse insulin resistance, and this is to reverse the behaviour that caused its development. As the behaviour that caused the insulin resistance was consumption of a poor quality diet, such diets must be abandoned in favour of a higher quality affaire. When higher quality diets devoid of refined carbohydrates and sugars are consumed the de novo synthesis of fatty acids in the liver is reduced and this reduces the production of triglycerides. Over time the lipids that have accumulated in the skeletal muscle are oxidised and the sensitivity of the insulin receptor increases. This allows the insulin to more effectively shuttle glucose into the cells, and a s a result blood glucose levels drop and this causes a concomitant decrease in insulin levels. As insulin levels drop the stimulation of anabolic pathways is reduced and the catabolism of fuel, including fatty acids proceeds at an accelerated rate. Improving insulin sensitivity therefore have beneficial effects on body fat levels, and weight loss ensues.
Although poor quality food is really the driver of insulin resistance, a lack of physical activity may contribute towards its development. Exercise has a potent blood glucose lowering effect because the glucose is needed as a metabolic fuel for skeletal muscle contraction. Following exercise the muscles experience an increase in their sensitivity for insulin, and the uptake to the myocytes increases. This insulin sensitising effect can last some hours following exercise. Exercise is therefore an effective way to control blood sugar levels through improved insulin sensitivity. The effect of exercise at lowering blood glucose levels has knock on effect on the insulin levels, because if blood glucose levels are adequately controlled insulin levels also remain within the normal physiological ranges. Exercise is therefore able to provide prophylactic protection against the development of insulin resistance, which explains the higher insulin sensitivity of athletes compared to sedentary individuals.
So exercise is able to prevent the deterioration of the insulin system that leads to insulin resistance, but can exercise reverse insulin resistance once it has developed? Well exercise may certainly help reverse insulin resistance because physical activity causes the oxidation of fatty acids in the skeletal muscle, the same fatty acids that may interfere with the insulin signal cascade and may contribute to insulin resistance. Exercise also depletes glycogen from the skeletal muscle and the liver. Empty glycogen stores are beneficial because if fructose and refined carbohydrates are consumed in such a condition, they are not converted to fatty acids, but instead are used to resynthesise glycogen. Exercise therefore has a preventive effect on the metabolic damage caused by low quality diets and may reverse some of their deleterious effects. However, it is unclear how effective exercise would be in the absence of dietary changes that sought to eliminate the low quality foods that were driving the insulin resistant state.
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