Body Recomposition Calculator

Losing fat while holding onto muscle is the goal of body recomposition, and it asks for more precision than a plain weight-loss plan. Where aggressive dieting often burns through lean tissue alongside fat, this approach is engineered to shift your composition without that cost.

The calculation starts from three numbers: your current weight, your current body fat percentage and your target body fat percentage. It splits your weight into fat mass and lean mass, assumes the lean mass stays the same, and finds the weight at which that lean mass would make up the target share: target weight = lean mass ÷ (1 − target body fat). The gap between today's weight and that target is the fat to lose. You also enter your maintenance calories (a TDEE calculator can supply them); the daily target is that figure minus 500 calories, protein is set at 1 gram per pound of lean mass, and the timeline assumes about a pound of fat lost per week. For the default 180-lb person at 25% body fat, protein comes to 135 g, about 1.65 g per kg of body weight, close to the 1.6 g per kg a day above which a 2018 meta-analysis (Morton et al.) found no further gain in lean mass from strength training with protein supplements.

Recomposition rewards patience far more than speed, and visible change tends to arrive slowly. Slashing calories too hard is the usual misstep, since it invites muscle loss and metabolic slowdown that make later fat loss tougher to come by. Treat these figures as a starting point: bodies respond differently, so watch your progress and how you feel, then adjust in small increments from there.