When the body loses sweat, it also loses which substance?

• A. Electrolytes.
• B. Carbohydrates
• C. Vitamins
• D. Proteins

Answer: (A)

Sweat is not just pure water—it's a filtrate that carries dissolved salts, primarily electrolytes. When you perspire, you lose water along with electrolytes such as sodium and chloride, and smaller amounts of potassium, calcium, and magnesium. These electrolytes are essential for maintaining fluid balance, nerve impulses, and muscle function, so losing them can contribute to dehydration symptoms like dizziness or cramps. Carbohydrates, vitamins, and proteins aren’t kept in sweat in meaningful amounts, so they aren’t the substances mainly lost with sweating. Understanding this helps explain why electrolyte-containing fluids are important in dehydration or heat-related illness management.