A low-carb diet can affect energy levels during exercise by impacting glycogen stores in the body. When carbohydrate intake is reduced, the body begins to rely more on fat as its primary energy source, which can lead to a shift in performance for some individuals. Initially, this transition may result in feelings of fatigue or decreased endurance. However, many people adapt over time and report more stable energy levels. It's essential for individuals on a low-carb diet to pay attention to hydration and electrolyte balance to maintain optimal performance during high-intensity workouts.