Effects of ordered eating on blood glucose, substrate utilization, and perceptual responses with a steady-state...

The sequence of a meal's macronutrient consumption influences postprandial blood glucose, but it is unknown whether altering the order of macronutrient consumption before exercise affects glycemic and metabolic responses during exercise.

Randomized controlled crossover trial.

Physically active adults who self-reported being free of cardiometabolic disease (n = 18; 8 male, 10 female) fasted for ≥8 h and were randomized to a rice-first or rice-last condition for one visit and the opposite for a second visit. Participants were asked to consume 150 g broccoli and 100 g chicken combined and 150 g rice separately. Post-meal, participants rested for 60 min before a 30-min run at 70 % of maximum heart rate. Blood glucose and respiratory exchange were measured regularly during rest and exercise.

There was a condition × time interaction for blood glucose (p < .001), with higher levels for rice-first than rice-last 30 min post-eating (133 ± 20 vs. 106 ± 21; p < .001). Rice-first led to a larger reduction in blood glucose than rice-last from pre- to post-exercise (21.4 ± 22.1 vs. 4.6 ± 23.5 mg/dL; p = .035). There was a condition × time interaction for respiratory exchange ratio at rest (p < .001), with 5-6 % higher values with rice-first than rice-last from 40 to 55 min postprandial. During exercise, respiratory exchange ratio was approximately 2.5 % higher with rice-first than rice-last (p = .029).

A rice-first meal pattern elicited a higher postprandial blood glucose shortly after eating and a larger blood glucose drop during exercise. Further, it led to a greater rise in resting respiratory exchange ratio, which was maintained during exercise.