Physical activity duration but not energy expenditure differs between daily and intermittent breakfast consumption in adolescent girls: a randomized crossover trial

Background: It is not known whether breakfast frequency affects physical activity (PA) in children or adolescents. Objective: This study examined the effect of daily compared with intermittent breakfast consumption on estimated PA energy expenditure (PAEE) in adolescent girls. Methods: Using a randomized crossover design, 27 girls (age 12.4 ± 0.5 y, body mass index 19.3 ± 3.0 kg∙m-2) completed two, 7-day conditions. A standardized breakfast (~1674 kJ) was consumed every day before 09:00 in the daily breakfast consumption (DBC) condition. The standardized breakfast was consumed on only three days before 09:00 in the intermittent breakfast consumption (IBC) condition alternating with breakfast omission on the remaining four days (i.e., only water consumed before 10:30). Combined heart rate- accelerometry was used to estimate PAEE throughout each condition. Statistical analyses were completed using condition by time of day repeated measures analysis of variance. The primary outcome was PAEE and the secondary outcome was time spent in PA. Results: Daily estimated PAEE from sedentary, light, moderate and vigorous intensities and total PAEE were not significantly different between the conditions. The condition by time of day interaction for sedentary time (P = 0.05) indicated that the girls spent 11.5 min/d more time sedentary in IBC compared with DBC during 15:30-bedtime (P = 0.04). Light PA was 19.8 min/d higher during DBC compared with IBC (P = 0.05), which was accumulated during wake-10:30 (P = 0.04) and 15:30-bedtime (P = 0.03). There were no significant differences in time spent in MPA or VPA between the conditions. Conclusions: Adolescent girls spent more time in light PA before 10:30 and after school and spent less time sedentary after school when a standardized breakfast was consumed daily compared with intermittently across seven days. However, breakfast manipulation did not affect estimated daily PAEE.