Lean Body Mass — Quick 8-Section Guide
1) Core idea
Lean Body Mass (LBM) is your weight minus fat mass. We estimate LBM using Boer, James, and Hume‑Weyers formulas, and optionally from body‑fat % if you know it.
2) Flow you can trust
- Enter weight, height, sex; pick units you prefer.
- We convert units exactly (1 in = 2.54 cm; 1 lb = 0.45359237 kg).
- We compute each formula and show an average.
- Optionally enter body‑fat % to add the direct LBM method.
3) Sanity checks
- LBM must be less than total weight; negative/invalid results are clamped to 0.
- James uses BMI-like terms; extreme BMI can distort results.
4) Shortcuts
- No body‑fat %? Use the average of Boer/James/Hume as your quick estimate.
- Muscle gain planning: target +1–2 kg/month (+2–4 lb) for novices.
5) Pitfalls
- Hydration shifts change scale weight; compare trends, not single days.
- Formulas are population-based; athletes may deviate.
6) Micro examples
- 70 kg, 170 cm, male → Boer ≈ 56 kg LBM; average across formulas ≈ mid‑50s.
- 65 kg at 22% body fat → LBM ≈ 50.7 kg via body‑fat method.
7) Mini‑FAQ
- Which formula is most robust? Boer for normal BMI ranges.
- Can I use pounds? Yes—1 kg = 2.20462262185 lb.
- How often to recheck? Every 4–6 weeks alongside photos and strength logs.
8) Action tip
Pair LBM tracking with circumference and performance metrics to confirm real muscle gain over water/scale noise.