Lean Body Mass Calculator
Calculate your lean body mass (muscle mass) and fat mass based on your total weight and body fat percentage.
What is lean body mass?
Lean Body Mass (LBM) is total body weight minus fat mass. Includes: Muscles, bones, organs, water, connective tissue - everything except fat. LBM = Weight x (1 - Body Fat %). Example: 180 lbs at 20% body fat = 180 x 0.80 = 144 lbs LBM, 36 lbs fat. LBM is metabolically active tissue that burns calories. Higher LBM = higher metabolism. Goal: Maximize LBM while minimizing fat through strength training and adequate protein.
Why is lean body mass important?
LBM importance: Determines BMR (more muscle = higher metabolism), affects calorie needs, indicates muscle loss/gain during diet, better health indicator than weight alone, predicts strength and function. Example: Person A 150 lbs, 10% fat (135 LBM), Person B 150 lbs, 25% fat (112.5 LBM) - Same weight, very different body composition and metabolism. Track LBM to ensure diet/exercise preserves muscle while losing fat.
How can I increase my lean body mass?
Build LBM strategies: Progressive strength training 3-5x/week (compound lifts: squats, deadlifts, bench press), eat slight calorie surplus (200-500 cal above TDEE), high protein (0.8-1g/lb body weight), adequate sleep (7-9 hours for recovery), patience (gain 0.5-2 lbs muscle/month max as beginner). Can't spot-build muscle. Focus on progressive overload, consistency. Muscle building is slow - 10-20 lbs/year is excellent progress for trained individuals.
How do I preserve lean mass while losing weight?
Preserve LBM during cut: Moderate deficit (500-750 cal, not extreme), high protein (0.8-1.2g/lb), strength training (maintain intensity, reduce volume if needed), adequate sleep, gradual weight loss (0.5-1% body weight/week). Losing 1-2 lbs/week, with proper protocol, 75-90% should be fat, 10-25% muscle/water. Extreme deficits or cardio-only approaches sacrifice muscle. Track body fat % monthly to monitor composition changes.