Body recomposition calculator

Everything starts at maintenance, your Total Daily Energy Expenditure. It is the calorie level where weight holds steady, built from basal metabolic rate times an activity factor. Enter a body fat percentage and the estimate switches to lean body mass, which tracks daily burn more closely than height and weight alone. For the example above, that lands maintenance near 2,700 kcal a day.

The recomposition target is maintenance minus a small percentage. The calculator scales that deficit to body fat and training age: leaner and more advanced bodies take 5 to 10 percent, while a beginner with fat to spare sits closer to 15 percent. Below maintenance there is fuel for fat loss; not so far below that the body starts spending muscle to cover the gap.

Protein is set next, at about 2.2 g per kg of lean body mass, and it is treated as a floor rather than a target to hit on average. Fat is held above a hormonal minimum of roughly 0.7 g per kg of bodyweight, and carbohydrate fills whatever calories remain. That is why the macro split reads protein-first: the muscle-protecting input is locked in before anything else moves.

A cut and a recomposition are not the same plan run at different speeds. A cut accepts losing some muscle to drop fat fast, often at 20 to 25 percent below maintenance. Recomposition refuses that trade. The deficit is kept small precisely so the body keeps building muscle while it loses fat, which is the whole point.

Dig too deep and two things happen. Muscle protein synthesis falls, so new muscle stops arriving, and the share of weight lost that is lean tissue climbs. You would lose weight faster, but a larger fraction of it would be the muscle you are trying to keep. The small deficit is the price of the recomposition being real instead of just weight loss with extra steps.

Protein is the lever that turns a deficit into a recomposition. In a calorie deficit the body looks for tissue to break down, and adequate protein plus resistance training tells it to spend fat and spare muscle. The calculator anchors the dose to lean mass rather than total weight, so two people at the same scale weight but different body composition get different protein targets. For the example, 64 kg of lean mass gives a floor near 141 g a day.

A common shorthand is 1.6 to 2.2 g per kg of bodyweight, and that range works well for people at moderate body fat. Scaling to lean mass instead avoids overshooting at higher body fat, where total weight overstates how much muscle there is to feed. Either way, hitting the floor most days matters far more than the exact decimal.

Over a 12-week block, the example profile projects to roughly 4.4 kg, about 10 lb, off the scale. That number looks modest, and it is supposed to. The scale understates recomposition because muscle is replacing some of the fat that leaves. The real progress shows up as body fat percentage falling, the waist tightening, and the lifts going up while bodyweight barely moves.

Treat the target as a starting line, not a verdict. Maintenance estimates carry an error of around 200 kcal a day, so check progress against a 7 to 10 day weight trend and adjust by 100 to 200 kcal a week. If the trend stalls and body fat is not moving, nudge calories down. If strength and recovery are sliding, nudge them up. The plan is the loop, not the first number.

For the full picture of the three levers, the realistic timeline, and how to read each proof signal, see the body recomposition guide.