Eureka 2019: Exercise Before Meals Improves Insulin Sensitivity in Obese Men

For the fifth year in a row, Endocrine News spoke with editors from Endocrine Society journals to get the scoop on the top endocrine discoveries of 2019. Here is part 9 of Eureka! 2019.

Associate editor for The Journal of Clinical Endocrinology & Metabolism as well as professor at the University of Colorado Anschutz Medical Campus in Aurora, Robert H. Eckel, MD, selected “Lipid Metabolism Links Nutrient-Exercise Timing to Insulin Sensitivity in Men Classified as Overweight or Obese,” by Wallis, G.A. and Gonzalez, J.T., et. al. and published in October. “The best time to exercise related to food intake has been debated,” Eckel says. “In particular, there is a deficit in understanding how the skeletal muscle response to a period of exercise training modifies this timing.”

In two experiments, researchers looked at acute metabolic responses to manipulating nutrient-exercise timing in 12 sedentary obese men (the “Acute Study”), then longer-term adaptations to carbohydrate-exercise timing in 30 sedentary obese men (the “Training Study”). Acute Study participants ate a standardized breakfast of 25% of their daily food intake requirements, followed by 90 minutes of rest, then a single bout of 60 minutes of cycling. They also reversed the events, having a session of exercise followed immediately by breakfast.

Training Study participants were randomized to three groups — a no-exercise control group, a breakfast before exercise group, or an exercise before breakfast group for six weeks. The Acute Study demonstrated that exercise before food intake increased whole body and skeletal muscle lipid utilization. The Training Study demonstrated that increases in lipid utilization were sustained with exercise before food intake for six weeks. Likewise, insulin sensitivity increased.

“In this well-designed and implemented study in overweight and obese men, the data demonstrate that exercise before nutrient intake produces increased muscle lipid utilization and improves insulin sensitivity,” Eckel says. “Now it’s an opportune time to extend this work to people with type 1 and type 2 diabetes.”