Which simplification is most correct when using the energy balance equation for short-term predictions (days to a few weeks)?

• A. Energy balance is useless short-term because water fluctuations completely mask any caloric effects and invalidate the equation.
• B. Energy balance gives exact weight change even in the short term because metabolic adaptation does not begin until months have passed.
• C. Using daily intake minus daily expenditure approximates short-term weight change reasonably well, though body composition shifts and water changes may occur.
• D. Short-term predictions require only measuring BMR; activity and intake can be ignored for periods under one month.

Answer: (C)