Assessment
Screening and Anthropometrics
Begin with informed consent, a health history, medication and allergy review, and a readiness screen such as the PAR-Q+. Measure height, weight, and waist circumference; compute BMI as kg/m². Categories: under 18.5, normal 18.5–24.9, overweight 25–29.9, obesity ≥30. BMI does not distinguish fat from lean mass. Waist thresholds - above 40 in (102 cm) in men and 35 in (88 cm) in women - flag elevated risk. Body composition options include skinfolds, bioelectrical impedance (hydration-sensitive), and DEXA.
Dietary and Energy Assessment
Dietary tools: 24-hour recall (fast, recall bias), food frequency questionnaire (usual pattern, less detail), food diary (3–7 days, reactivity), weighed record (precise, burdensome). Estimate resting metabolic rate with Mifflin–St Jeor: men 10W + 6.25H − 5A + 5; women 10W + 6.25H − 5A − 161, then multiply by an activity factor of 1.2–1.9.
Worked Example
A 30-year-old woman, 65 kg, 165 cm: RMR = 650 + 1,031.25 − 150 − 161 = 1,370 kcal. With a moderate activity factor of 1.55, TDEE ≈ 2,124 kcal. A 500 kcal deficit gives about 1,624 kcal/day for roughly 0.5 kg/week loss.
Traps
Using BMI alone; treating one 24-hour recall as typical intake; forgetting to convert pounds to kilograms (divide by 2.2); overestimating activity; measuring waist over clothing.