Body Recomposition Calculator
Body recomposition means losing fat while keeping or building muscle. Start with your number from our body fat calculator, then set a goal below.
What Is Body Recomposition?
Body recomposition, or body recomp, means changing what your body is made of: less fat, with muscle kept or added. Your weight may change slowly or not at all, so the scale can hide real progress. That is why this calculator starts from your body fat percentage rather than your weight.
How This Calculator Works
The calculator first splits your weight into lean mass and fat mass, then works out what you would weigh at your goal if your lean mass stayed the same.
Calorie needs come from the Katch-McArdle equation, which uses lean mass directly, multiplied by your activity level.
Activity factors are 1.375 for light, 1.55 for moderate, and 1.725 for high. The calorie target is set 10% below maintenance. That figure is our chosen starting point, not a rule, because a smaller deficit makes it easier to train hard while you lose fat.
Worked Example
Take a person who weighs 200 lbs at 25% body fat, with a goal of 15%:
- Lean mass: 150 lbs. Fat mass: 50 lbs.
- Goal weight: 150 ÷ 0.85 = 176.5 lbs, which means losing 23.5 lbs of fat.
- At 0.5 to 1 lb of fat a week, that takes about 24 to 48 weeks.
- At moderate activity, maintenance is about 2,850 calories, so the target is about 2,570.
- Protein: at least 145 g a day.
Protein and Training
The protein target in this calculator is 1.6 g per kilogram of body weight. A 2018 meta-analysis found that gains in fat-free mass from resistance training stopped rising above roughly that intake. The studies excluded intentional dieting, so treat it as a minimum during a calorie deficit. Resistance training is what tells your body to keep muscle while you lose fat.
Who Gets the Best Results?
Recomposition tends to be easier for beginners and for people returning to training. Experienced lifters at low body fat usually see much slower changes. Nobody can predict your exact pace, so the timeline here is a planning range and not a promise.
How to Track Progress
- Recheck your number with the body fat calculator every few weeks, under the same conditions.
- Follow your lean mass with the lean body mass calculator. If it drops quickly, your deficit may be too large.
- Use the ffmi calculator to see how your muscularity changes for your height.
Frequently Asked Questions
Yes, especially if you are new to resistance training or returning after a break. It gets harder as you become leaner and more experienced.
Not always, but losing a meaningful amount of fat usually requires a modest deficit. That is why this calculator sets its target just below maintenance.
The calculator holds your lean mass steady. If you also gain muscle, you will reach the same body fat percentage at a higher weight.
Every few weeks is enough. As your weight and lean mass change, your calorie and protein targets change too.