Body Recomposition Calculator
Body recomposition means losing fat and building muscle at the same time, rather than bulking to gain and then cutting to lose. Instead of running a surplus or a deficit, you eat at maintenance and let high protein and hard training shift your body composition while the scale stays roughly flat. This calculator estimates your maintenance calories from your bodyweight, height, age, and activity, then sets the protein target that makes a recomp work.
Recomp is not the fastest path for everyone. It works best for newer lifters, lifters returning after a layoff, and lifters carrying higher body fat, all of whom have plenty of room to build muscle and burn fat at once. If you are already lean and experienced, a dedicated bulk or cut will usually move you forward faster, because eating at maintenance limits how quickly you can do either. Being honest about which group you fall into is the difference between a recomp that pays off and months of spinning your wheels.
How the targets are computed
Your maintenance is your total daily energy expenditure (TDEE), the calories you burn in a day. The calculator first finds your basal metabolic rate (BMR) with the Mifflin-St Jeor equation: for men, BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5, and for women the same formula ends in - 161 instead of + 5. If you enter a body fat percentage, it switches to the Katch-McArdle equation, BMR = 370 + 21.6 x lean mass(kg), which uses lean mass and is more accurate when your body fat is known.
BMR is then multiplied by an activity factor to get maintenance: sedentary x 1.2, light x 1.375, moderate x 1.55, active x 1.725, and very active x 1.9. A recomp targets that maintenance number directly, holding roughly plus or minus 100 calories rather than a surplus or a deficit. Protein is set at 1.8 to 2.7 g/kg of bodyweight, the high end of the researched range. That high protein intake is the active ingredient in a recomp: at maintenance calories it is what preserves and builds muscle while your body draws on fat stores, so it is the number to hit before anything else.
What results to expect
Recomposition is slow by design. Expect visible change over 3 to 6 months, not weeks, because building muscle and losing fat simultaneously is harder than doing either alone. The payoff is that you never go through a bulk-and-cut cycle, you just get steadily leaner and more muscular at a stable bodyweight.
The scale is the wrong tool to track a recomp. Because muscle gained roughly offsets fat lost, your weight can stay nearly flat for months while your body changes underneath it, which is discouraging if the scale is all you watch. Track progress photos in the same lighting every two to four weeks, a waist tape measurement, and your gym lifts instead. When the tape shrinks, the mirror improves, and your lifts climb while the scale barely moves, the recomp is working exactly as it should.
Frequently asked questions
Can you lose fat and gain muscle at the same time?
Yes, under the right conditions. It happens most readily for newer lifters, people returning to training after a break, and people carrying higher body fat, because all three have a large capacity to build muscle while burning fat. It is slower and harder for lean, experienced lifters, who usually progress faster by dedicating a phase to bulking or cutting. The keys are eating at maintenance and keeping protein high.
How many calories should I eat for body recomposition?
Eat at maintenance, the number of calories you burn in a day, rather than a surplus or a deficit. This calculator estimates that figure from your bodyweight, height, age, and activity. Hold roughly within 100 calories of it and let high protein and progressive training, not a calorie swing, drive the change in your body composition.
How long does body recomposition take?
Think in months, not weeks. Expect visible change over roughly 3 to 6 months, because gaining muscle and losing fat at once is slower than doing either alone. Your scale weight may barely move across that window even as your waist shrinks and your lifts climb, so judge progress by photos, tape, and the gym rather than the scale.
Should I do cardio during a recomp?
Cardio is fine and can help. It adds to the calorie side of the equation, which supports the fat loss part of a recomp, and it improves conditioning and health. Just do not let it eat into your recovery from lifting, since progressive strength training is what builds the muscle. Keep it moderate, a few manageable sessions a week, and prioritize your lifting and protein.