Three low-carb meals within 24 hours can lower post-meal insulin resistance by more than 30 percent.
However, high-carb meals sustain insulin resistance, a condition that leads to high blood pressure, prediabetes and diabetes, according to a University of Michigan study.
The study also found that two hours of moderate-intensity exercise, which is supposed to lower insulin resistance and blood sugar levels, has no impact on these results.
To the contrary, blood sugar levels increase after the exercise, said Katarina Borer, professor in the School of Kinesiology.
Insulin is a hormone critical in metabolism.
Insulin sensitivity refers to insulin’s ability to efficiently respond to and regulate glucose in the blood, so that our cells can use it for energy and other functions.
If we’re insulin resistant, insulin is less effective in removing glucose from the bloodstream and the pancreas must produce more insulin to help.
This can eventually lead to diabetes.
The study sample was small, Borer said, but the results are significant, in part, because they reinforce results in two preceding studies and one 2015 review on high-carbohydrate diets and their negative effects on insulin.
In the U-M study, 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, Borer said.
The high-carb group’s diet fell in line with the 45-to-60 percent daily carbohydrate intake the departments of Agriculture and Health and Human Services recommend, Borer said.
Because exercise did not lower insulin resistance, it suggests that the insulin reaction the subjects experienced after the evening meal was driven by an intestinal response to the carbohydrate, and not by exercise.
But this doesn’t mean exercise doesn’t influence insulin, she said.
Going forward, Borer’s lab will examine the timing of meals and whether insulin-lowering effect can be produced in the morning and whether blood sugar will decline when women exercise after low-carbohydrate meals.
The study, “Third exposure to a reduced carbohydrate meal lowers evening postprandial insulin and GIP responses and HOMA-IR estimate of insulin resistance,” appears in the Oct. 31 edition of PLOS ONE.
News source: University of Michigan.
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