Is Breakfast the Most Important Meal of the Day? A Review of the Literature

A recent narrative review investigated the role of breakfast in exercise performance and body composition. The review considered whether breakfast improves training performance or body composition. It found that pre-exercise feeding can help long sessions (>60 minutes), which is mostly true for morning workouts and even for some evening workouts after breakfast has been skipped, where small performance increases are observed. However, a placebo breakfast containing no actual calories or carbohydrates can improve endurance performance relative to water-only conditions in sub-60-minute cycling efforts. In contrast, a placebo breakfast does not appear to have the same effect for longer-duration exercise. When examining acute resistance training outcomes, lifting fasted in the morning can result in fewer reps on the first one or two sets but without a significant effect on subsequent sets. Interestingly, a placebo breakfast may mitigate some of those effects, suggesting potential psychological effects of breakfast, especially given its perceived importance in many cultures. In the long term, breakfast does not seem to be a game-changing variable for gaining strength or muscle, provided protein and calories are adequate and training is done in a fed state. However, training in a fasted state has been shown to lead to greater strength gains, but muscle growth outcomes remain largely unaffected. The authors also noted that skipping breakfast may lead to managing bodyweight in free-living conditions, but this is likely due to consuming fewer overall calories rather than a specific mechanism behind skipping breakfast. The review concluded that having a balanced breakfast can be a great way to support training, but making sure not to be hungry during exercise remains a solid and simple approach. Ultimately, the importance of breakfast in exercise and body composition is nuanced and depends on individual circumstances.