Low-carb meals lower post-meal insulin resistance by more than 30 percent, reducing the associated risk of high blood pressure, prediabetes, and diabetes.
In the University of Michigan study, published in PloS One, 32 post-menopausal metabolically healthy women were divided into four groups and given meals of either 30 or 60 percent carbohydrates with or without moderate-intensity exercise before meals. The low-carb group showed a reduction in insulin resistance after the third meal in the evening, but the high-carb group sustained high post-meal insulin.
"We showed an acute, one-day reduction in insulin resistance after the third low-carbohydrate meal eaten in the evening, so one could argue that this is transient and insignificant," study leader Katarina Borer said. "But at least two other studies where high-carbohydrate meals were fed to volunteers for 5 and for 14 days show that the outcome was worrisome. These subjects developed increased fasting insulin secretion and insulin resistance, increased glucose release by the liver which produced high blood sugar, and dramatically lowered fat oxidation that contributes to obesity. These then were more persistent effects that could be a path to prediabetes and diabetes.
"What is remarkable about our findings is that they show that a simple dietary modification of reducing the carbohydrate content of the meals can, within a day, protect against development of insulin resistance and block the path toward development of prediabetes while sustained intake of high carbohydrate diets as shown in the other two studies led to increased fasting insulin secretion and resistance. And even more surprising and amazing is that exercise before the meals made the subjects more carbohydrate intolerant - that is, it increased evening blood sugar levels."