Question 1

What is lean body mass (LBM)?

Accepted Answer

Lean body mass is everything in your body that is not fat: muscle, bone, organs, blood, and water. It accounts for 60-90% of total body weight depending on body composition. LBM is the main driver of resting metabolic rate.

Question 2

How is lean body mass calculated?

Accepted Answer

We use the Boer formula, validated against DXA scans. For men: LBM (kg) = 0.407 x weight (kg) + 0.267 x height (cm) - 19.2. For women: LBM (kg) = 0.252 x weight (kg) + 0.473 x height (cm) - 48.3. The result is then converted to pounds.

Question 3

What is a normal lean body mass?

Accepted Answer

For adult men, LBM typically ranges 70-85% of total body weight. For adult women, 65-75%. Athletes can exceed 85% (men) or 75% (women). Lower LBM is associated with older age and higher body fat.

Question 4

How is LBM different from fat-free mass?

Accepted Answer

Lean body mass includes essential fat (about 2-3% for men, 5-9% for women) in cell membranes and organs. Fat-free mass excludes all fat. The two are often used interchangeably in practice, with LBM slightly higher.

Question 5

Is this lean body mass calculator free with no signup?

Accepted Answer

Yes. The BodyStd LBM calculator is 100% free, runs in your browser, and requires no account or personal information. Enter your sex, weight, and height to get instant results.

Question 6

How do I increase lean body mass?

Accepted Answer

Progressive resistance training 3-5 days per week, 0.7-1 g of protein per pound of body weight daily, a small calorie surplus (250-500 kcal), and 7-9 hours of sleep. Expect 0.25-0.5 lb of muscle gain per week for men, less for women.

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