4. Discussion
hunger, cardiometabolic disease, post-lunch glycaemia, fullness, tiredness
This study is the first to report higher post-lunch glycaemia and insulinaemia in response to breakfast omission versus breakfast consumption among adolescent girls who habitually consume breakfast, indicating a ‘second meal effect’. Moreover, the large magnitude of these post-lunch differences meant that glycaemia and insulinaemia were higher across the 5 h spanning pre- and post-lunch when breakfast was omitted versus consumed. This contributed to a higher MLI with breakfast omission, despite the lower TAG response. Carbohydrate oxidation and fat oxidation were lower and higher, respectively, with breakfast omission versus consumption; the effect for IAUC was reversed after lunch. Although Fatmax and peak fat oxidation 2 h after lunch were unaffected, omitting breakfast appeared to reduce exercise enjoyment.The higher post-lunch glycaemia and insulinaemia in response to breakfast omission versus consumption suggests that adolescent girls respond similarly to adults [Regarding consistency, all but one of the girls in our study exhibited higher post-lunch glycaemia and insulinaemia and higher peak concentrations when they omitted breakfast. This, coupled with the small glucose response to the low GI high-fibre breakfast, meant that glycaemia was higher across the 5 h experimental period, despite the girls consuming less carbohydrate with breakfast omission. If repeated habitually, a series of higher overall and peak glycaemic responses induced by breakfast omission could contribute to cardiometabolic disease among adolescent girls [Reduced carbohydrate availability with breakfast omission may have contributed to the strong tendency for lower afternoon exercise enjoyment (i.e., 2 h post-lunch), as well as the lower energy levels and higher tiredness reported across the day when compared with breakfast consumption. Breakfast omission also increased hunger and decreased fullness pre-lunch, supporting past research among adolescent girls [The acute, controlled nature of this study was a strength due to the minimal influence of confounders, but did not permit an understanding of chronic and/or free-living effects. Our sample of healthy adolescent girls who habitually consumed breakfast is relevant for cardiometabolic disease prevention, which is more effective than a cure [To conclude, we report for the first time that breakfast omission increases subsequent glycaemia and insulinaemia when compared with breakfast consumption among adolescent girls who habitually consume breakfast. Omitting breakfast may also reduce afternoon exercise enjoyment, with Fatmax and exercise peak fat oxidation being unaffected. These findings suggest effective strategies are required to promote sustained breakfast consumption among adolescent girls for cardiometabolic disease prevention.