Signs of dehydration in the body include thirst, dry mouth, and fatigue. As dehydration progresses, symptoms may include dizziness, headache, and reduced urine output, often darker in color. Severe dehydration can lead to confusion, rapid heartbeat, and fainting. During exercise, it’s crucial to stay hydrated to maintain performance and prevent these adverse effects. Regularly consuming fluids before, during, and after workouts can mitigate the risks associated with dehydration, ensuring optimal bodily function and performance.