Does consuming breakfast influence activity levels? An experiment into the effect of breakfast consumption on eating habits and energy expenditure

Objective: To experimentally compare the effects of eating or skipping breakfast on energy expenditure, activity levels and dietary habits. Design: A randomised cross-over trial, lasting 2 weeks. Participants were provided breakfast during one week and were required to fast until mid-day during the other week. Setting: University campus. Subjects: Forty-nine participants (twenty-six female and twenty-three male participants) were recruited. Food intake was monitored using food diaries, and energy expenditure was assessed using pedometers and heart rate monitors. Morningness–eveningness, physical activity and health were assessed using validated questionnaires. Results: Across all participants, daily energy expenditure did not differ between the two experimental conditions. Total energy intake over 24 h did not vary with condition (male participants: 8134 (SD 447) kJ/d and 7514 (SD 368) kJ/d; female participants: 7778 (SD 410) kJ/d and 7531 (SD 535) kJ/d, for the breakfast and no-breakfast conditions, respectively). However, when comparing habitual breakfast eaters with those with irregular or breakfast-skipping habits, it was found that male non-habitual breakfast eaters consumed significantly (P50?029) more energy during the breakfast condition. Furthermore, female participants who were habitual breakfast eaters were found to eat significantly (P50?005) more and later in the day under the no-breakfast condition. Conclusions: Although the suggestion that breakfast is a behavioural marker for appropriate dietary and physical activity patterns is not refuted by the present findings, our data suggest that the effect of breakfast may vary as a function of gender and morning eating habits, and thus there may be other mechanisms that link BMI and breakfast consumption behaviour.