Effect of lunch with different calorie and nutrient balances on dinner-induced postprandial glucose variability

Aim: This study aimed to examine the effect of lunches with different caloric contents (Study 1) and nutrient balances (Study 2) on dinner-induced postprandial glucose fluctuation. Methods: Energy trial (Study 1): Thirteen healthy young participants (n = 10 men, n = 3 women) were investigated to determine the effects of different caloric intakes at lunch on glucose level variability. The study was comprised of four trials (no lunch, low lunch, standard lunch, and high-energy lunch). Energy balance trial (Study 2): Fourteen healthy young adults (n = 8 men, n = 6 women) were investigated to determine the effect of different nutrient balances during lunch on glucose level variability. The study consisted of four trials (standard, protein-rich, fat-rich, and carbohydrate-rich). In studies 1 and 2, each trial was spaced at least 24 full hours apart, and breakfast and dinner were tested as meals. The mealtimes for each trial were then aligned. Continuous glucose monitoring was used to assess the blood glucose fluctuations. Results: Study 1: The no-lunch (95% CI 95.5–149.7) and low-energy lunch (95% CI 90.8–143.1) trials had significantly higher values in the incremental area under the curve (iAUC) of postprandial blood glucose at dinner compared to the standard (95% CI 55.4–90.0) and high-energy lunch (95% CI 29.3–54.6) trials (P = 0.006, P = 0.001 vs. none), (P = 0.004, P = 0.001 vs. low-energy trial). Study 2: A significantly higher postprandial blood glucose iAUC for dinner was found in the fat-rich trial (95% CI 58.5–114.0) than that in the protein-rich (95% CI 25.6–63.9) and standard (95% CI 25.6–112.4) trials, (P = 0.006, P = 0.035 vs. fat-rich trial). Conclusions: Our findings indicate that skipping lunch and low-calorie or high-lipid intake increased postprandial blood glucose levels after dinner.