Overview
This lecture covers key nutritional calculations including ideal body weight (IBW), percent ideal body weight, BMI, and calorie estimation, explaining formulas, steps, and classification ranges for healthy assessment.
Ideal Body Weight (IBW) Calculation
- IBW is a guideline based on height to estimate a healthy weight for longevity, not appearance.
- For women: 100 lbs for first 5 ft + 5 lbs for each inch over 5 ft.
- For men: 106 lbs for first 5 ft + 6 lbs for each inch over 5 ft.
- To account for body frame size, calculate a range by adding/subtracting 10% from IBW.
Practice Examples & Adjustments
- Example for 5'6" female: 100 + (6×5) = 130 lbs; range: 117–143 lbs (±10%).
- Example for 6'0" male: 106 + (12×6) = 178 lbs; range: 160–196 lbs (±10%).
- For additional height/inches, remember 12 inches in 1 foot.
Percent Ideal Body Weight
- Formula: Actual weight ÷ IBW × 100%.
- Classifications: <90% (underweight), 90–120% (healthy), >120% (overweight), >150% (obese), >200% (morbidly obese).
- Example: 185 lbs actual, 130 lbs IBW → 185÷130×100% ≈ 142% (overweight).
BMI Calculation & Classification
- BMI formula: (Weight in lbs × 703) ÷ (Height in inches)².
- Classifications: <18.5 (underweight), 18.5–24.9 (healthy), 25–29.9 (overweight), 30–39.9 (obese), ≥40 (morbidly obese).
- Note: BMI is less accurate for athletes and frail older adults.
Calorie Estimation (Mifflin-St Jeor Equation)
- Equations provided for men and women to estimate resting metabolic rate (RMR).
- Convert weight to kg (lbs ÷ 2.2) and height to cm (inches × 2.54).
- Total energy needs = RMR × activity factor (1.2–1.5 based on activity level).
- Example: Woman, 165 lbs, 67 in, 28 yrs: RMR ≈ 1,500 kcal; total ≈ 2,000 kcal if moderately active.
Key Terms & Definitions
- IBW (Ideal Body Weight) — Estimated healthy weight based on height.
- Percent Ideal Body Weight — Actual weight as a percent of IBW.
- BMI (Body Mass Index) — Weight-to-height ratio for health assessment.
- RMR (Resting Metabolic Rate) — Calories needed at rest.
- Activity Factor — Multiplier to adjust calories for activity level.
Action Items / Next Steps
- Complete practice calculations on Blackboard (IBW, percent IBW, calories).
- Review lecture formulas; memorize IBW, percent IBW, and BMI calculations.
- Check answers with provided solutions and seek help if needed.
- Prepare for exam questions on these calculations.