Body Recomposition Calculator

This calculator estimates calorie cycling around resistance-training days. It first converts body weight to kilograms and subtracts the entered body-fat share to estimate lean mass. Lean mass enters a Katch-McArdle-style basal metabolic rate of 370 plus 21.6 calories for each kilogram of lean mass. Activity level then scales that result by 1.2, 1.375, 1.55, or 1.725 to form the rounded TDEE used throughout the remaining calculations. Training-day calories are fixed at 112 percent of estimated TDEE, while rest-day calories are 82 percent. Training days per week does not change either daily target. Instead, it decides how many times each target appears in the seven-day total.

The weekly net deficit is seven maintenance days minus that cycling schedule, and projected fat loss divides the deficit by 3,500 before displaying its absolute value. More training days can reduce the deficit and can eventually create a surplus; because the projection uses an absolute value, the displayed “fat loss” can remain positive even when weekly deficit is negative. Check the signed weekly-deficit output before interpreting that projection. Body weight, body-fat estimate, and activity selection all move TDEE and therefore both daily calorie targets. The model does not estimate muscle gain, metabolic adaptation, training energy separately, macro targets, or measurement uncertainty in body fat. It is a simplified schedule comparison, not evidence that simultaneous fat loss and muscle gain will occur.