Metabolism & Energy Balance
What this domain covers
Metabolism & Energy Balance tests your ability to estimate how many calories a client burns and how to change intake or output to move weight in the intended direction. Questions cover BMR versus RMR, the components of TDEE, prediction equations, and the realities of metabolic adaptation.
Core rules
- TDEE has four parts: BMR (roughly 60-75% of total), TEF (about 10%; protein 20-30%, carbohydrate 5-10%, fat 0-3%), EAT, and NEAT. NEAT is the most variable component and often falls during dieting.
- Mifflin-St Jeor: men = 10(kg) + 6.25(cm) − 5(age) + 5; women = the same − 161. Multiply by an activity factor: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra active.
- Energy balance is dynamic. The 3,500-kcal-per-pound rule is an approximation; adaptation, reduced NEAT, and changes in body composition mean loss slows over time.
- A sensible loss rate is 0.5-1% of body weight per week; a 10-20% deficit or 300-500 kcal is common. Surpluses for muscle gain are usually 200-300 kcal.
Worked example
A 35-year-old woman, 70 kg, 165 cm, moderately active. BMR = 10(70) + 6.25(165) − 5(35) − 161 = 700 + 1,031 − 175 − 161 = 1,395 kcal. TDEE = 1,395 × 1.55 ≈ 2,162 kcal. For about 0.5 kg/week loss, subtract roughly 500 kcal: a target near 1,650 kcal. Recheck after two to three weeks against the weight trend rather than a single day.
Traps
Using BMR as maintenance, applying the highest activity multiplier by default, overestimating exercise burn, and assuming a calculated deficit will produce perfectly linear loss. Do not label every plateau a metabolic slowdown; adherence and NEAT changes explain many stalls.