What is the range of adult maintenance water requirement per kcal?

• A. 0.5-2 ml/kcal
• B. 5-10 ml/kcal
• C. 10-20 ml/kcal
• D. 0.05-0.2 ml/kcal

Answer: (A)

Maintenance fluid needs in adults are tied to energy requirements, so the amount of water you need each day roughly follows how many kilocalories you burn. In routine practice, about 0.5 to 2 mL of water are needed per kilocalorie of energy requirement, with some variation based on temperature, activity level, fever, and kidney function. This range captures the reality that lean individuals in cooler conditions may need less, while hotter environments or higher metabolic demands push needs higher. For example, someone with an estimated 2000 kcal/day requirement would fall roughly in the 1000–4000 mL/day water range, though many adults sit around about 2 liters daily when other factors are average. The other options would imply far too little or far too much water per kilocalorie for typical adults.