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: Under a randomized crossover design, 27 girls [mean ± SD age: 12.4 ± 0.5 y, body mass index (in kg/m2): 19.3 ± 3.0] completed two 7-d conditions. A standardized breakfast (∼1674 kJ) was consumed every day before 0900 in the daily breakfast consumption (DBC) condition. The standardized breakfast was consumed on only 3 d before 0900 in the intermittent breakfast consumption (IBC) condition, alternating with breakfast omission on the remaining 4 d (i.e., only water consumed before 1030). Combined heart rate accelerometry was used to estimate PAEE throughout each condition. Statistical analyses were completed by using condition × time of day repeated-measures ANOVA. The primary outcome was PAEE and the secondary outcome was time spent in PA.

Results: Daily estimated PAEE from sedentary or light-, moderate-, or vigorous-intensity PA and total PAEE were not significantly different between the conditions. The condition × time of day interaction for sedentary time (P = 0.05) indicated that the girls spent an additional 11.5 min/d being sedentary in the IBC condition compared with the DBC condition from 1530 to bedtime (P = 0.04). Light PA was 19.8 min/d longer in the DBC condition than in the IBC condition (P = 0.05), which was accumulated from waking to 1030 (P = 0.04) and from 1530 to bedtime (P = 0.03). There were no significant differences in time spent in moderate PA or vigorous PA between the conditions.

Conclusions: Adolescent girls spent more time in light PA before 1030 and after school and spent less time sedentary after school when a standardized breakfast was consumed daily than when consumed intermittently across 7 d. However, breakfast manipulation did not affect estimated daily PAEE. This trial was registered at www.isrctn.com as ISRCTN74579070.