Low carbohydrate meals after exercise may benefit diabetics

New research from the University of Michigan shows that meals eaten after each exercise session have an important impact on controlling blood sugar.

High blood sugar is a hallmark of type 2 diabetes, and impaired control of blood sugar is also a major risk factor for other chronic diseases, such as heart disease. Jeffrey Horowitz, professor in the School of Kinesiology at University of Michigan, is the senior author of the study.

The study follows up on earlier research demonstrating that many of the health benefits of exercise stem from the most recent exercise session. In fact, even in people who exercise regularly many of the health benefits of exercise wear off after several hours or at best after only a few days without exercise.

This new study suggests that eating meals with a relatively low carbohydrate content after exercise (but not low in calories) improved the control of blood sugar into the next day. But when the research participants ate low-calorie meals after exercise, the improvement in blood sugar was no different compared with when they ate enough calories to match the energy expended during exercise. Therefore, exercise can improve the control of blood sugar even without cutting calories.

Horowitz stressed that weight loss is important for improving metabolic health in overweight people who are at risk for diabetes, but these study results suggest that people can still acquire some key health benefits from exercise without under-eating or losing weight.

In addition, Horowitz noted that their findings do not suggest that people at risk for diabetes should go on strict low-carbohydrate diets. In their study, during the so-called low carbohydrate treatment, the research participants still ate more than 200 grams of carbohydrates in the hours after exercise. By comparison, some of the popular low carbohydrate diets can restrict carbohydrate intake to less than 20 grams per day.

"Carbohydrates are a very important part of a balanced diet, especially in people who exercise regularly," Horowitz said. "In general, it is important to replenish at least some of the carbohydrate stores used up during exercise so you have this major fuel source ready for your next exercise session."

The paper, "Energy deficit after exercise augments lipid mobilization but does not contribute to the exercise-induced increase in insulin sensitivity," appears online in the Journal of Applied Physiology. Other authors are Sean A. Newsom, Simon Schenk, Kristin M. Thomas, Matthew P. Harber, Nicolas Knuth, all of the School of Kinesiology, and Naila Goldenberg, Department of Internal Medicine, U-M Health System.