A clinician uses a baseline estimated energy need of 2,200 kcal/day for a healthy 45-year-old patient. Estimate the energy need for that same patient at age 65 using the 5% per decade after 50 guideline, and explain the calculation steps.

• A. 2,200 kcal/day unchanged, because baseline adult needs remain constant through life regardless of age-related changes.
• B. Approximately 1,980 kcal/day, applying 10% reduction for 15 years after 50 (2,200 × 0.90).
• C. Approximately 2,310 kcal/day, because metabolic rate increases with age and so needs go up by 5%.
• D. Approximately 2,090 kcal/day, because a single decade after 50 reduces needs by 5% (2,200 × 0.95).

Answer: (D)