Skipping Breakfast: Performance Hack or Hindrance?
How Skipping Breakfast Affects Strength, Endurance, and Fat Loss—And When It Doesn’t
Does skipping breakfast help or hurt your training and physique goals? For many lifters and athletes debating early sessions or time-restricted eating, this review brings some needed, data-driven clarity. This comprehensive narrative review critically examines how breakfast—whether consumed or skipped—impacts exercise performance and adaptation in both resistance and endurance contexts. Let’s get into it.
Key Points
Aim
The review analysed all experimental human studies available before November 2024 that looked at the effect of breakfast consumption vs. omission on acute and chronic exercise performance. It covers both endurance and resistance training, as well as body composition changes.
The central aim: To clarify when, if ever, eating breakfast truly matters for strength, muscle gain, fat loss, and athletic performance—especially given modern trends like intermittent fasting and “fasted” training.
Methods
The team performed a thorough literature search targeting interventions with a direct breakfast comparison, published before November 2024, including an exercise component (endurance or resistance) and measuring performance/adaptation or body composition.
Both acute (i.e., during or immediately after a workout) and long-term adaptations (body composition, strength, endurance) were considered, and studies spanned a variety of populations, including athletes and recreationally active adults.
Results
Endurance Performance
Breakfast consistently improved morning endurance exercise lasting over 60 minutes, regardless of workout intensity.
Skipping breakfast impaired evening time trial performance (0.8–4.5% reduction, such as a 3.5-second loss in a 2000m row or a 38-second loss in a 20km cycle), even if meals were eaten later in the day—but this difference is only meaningful in high-level competition, not day-to-day training.
No significant difference was found for short-duration (<60 min) morning endurance exercise or for afternoon resistance training, provided total daily caloric intake was matched.
Resistance Training
Skipping breakfast led to fewer repetitions in the first sets of early-morning resistance sessions (about 15 fewer in squats and 6 fewer in the bench press)—but this difference was minimal in later sets and disappeared entirely with a placebo (psychological effect).
For afternoon resistance training, there were no performance differences when the same amount of food was consumed before training, whether split between breakfast and lunch or only at lunch.
Longitudinal (multi-week) resistance training studies (e.g., with time-restricted eating, often skipping breakfast) found no meaningful difference in muscle growth or strength gains as long as overall protein and caloric needs were met.
Body Composition
Regularly skipping breakfast (in ad libitum, uncontrolled settings) led to slightly greater fat loss—primarily by unintentionally lowering calorie intake for the rest of the day (often a 132–650 kcal/day energy deficit).
However, when calories were controlled between groups, no differences in fat or muscle loss were found, emphasising that total intake (not meal timing) is what matters most.
Skipping breakfast is not recommended for those struggling to maintain or gain weight, or for athletes with high energy needs.
