The US Navy method uses circumference measurements and is accurate to ±3% for most people. It is far more useful than BMI for athletes or anyone with significant muscle mass.

Essential fat (3–5% for men, 10–13% for women) is the minimum required for healthy hormones and organ function. Going below this is dangerous.

Track Lean Body Mass (LBM) over time. If your weight drops but LBM stays flat, you are losing fat — the goal of any sensible cut.