A common dietary mistake that inhibits fitness goals is skipping meals, particularly breakfast. This can lead to overeating later in the day due to increased hunger levels. Additionally, many may consume processed foods high in sugar and unhealthy fats, which can lead to energy crashes and reduced motivation for exercise. Not planning meals can also result in poor choices when hunger strikes. Overall, maintaining a consistent meal schedule with balanced macronutrients is crucial for optimizing energy levels and supporting fitness objectives.