High blood sugar levels can negatively impact energy during workouts by causing fatigue and decreased performance. When blood sugar is elevated, the body may struggle to effectively use glucose for energy, leading to feelings of sluggishness. Additionally, hyperglycemia can result in dehydration and increased electrolyte loss, which further undermines physical performance. Conversely, low blood sugar can lead to dizziness, weakness, and impaired concentration. Maintaining stable blood sugar levels through balanced nutrition is essential for optimal energy levels and performance during physical activities.