Calculate your fat-free mass and body composition
Lean body mass (LBM) is everything in your body except fat โ muscles, bones, organs, blood, skin and water. It is also called fat-free mass (FFM). Knowing your LBM is genuinely useful for several reasons: it gives you a more accurate BMR calculation, helps set protein targets for muscle building, and lets you track whether you are losing fat or muscle during a diet.
When you lose weight, not all of it is fat. Some is water, some may be muscle. Tracking LBM over time tells you whether your training and nutrition plan is helping you preserve muscle while losing fat โ which is the actual goal of most body recomposition efforts.
Protein requirements are based on lean body mass, not total body weight. The standard recommendation of 1.6-2.2g of protein per kg applies to lean mass โ so a 90 kg person with 30% body fat has an LBM of 63 kg and needs about 100-138g of protein daily, not 144-198g based on total weight.
LBM is also the primary driver of metabolic rate. Muscle tissue burns roughly 13 calories per kg per day at rest, compared to about 4 calories per kg for fat tissue. This is why building muscle increases your metabolism and makes long-term weight management easier.
Progressive overload strength training is the most effective way to increase muscle mass. This means gradually increasing the weight, reps or intensity of your workouts over time. Compound movements โ squats, deadlifts, bench press, rows and overhead press โ recruit the most muscle fibres and give the biggest stimulus for growth.
Nutrition matters equally. You need a slight calorie surplus (200-300 calories above maintenance) and adequate protein to build new muscle tissue. Sleep is where the actual muscle repair and growth happens โ 7-9 hours is optimal. Chronic sleep deprivation significantly impairs muscle protein synthesis.