Body Recomposition Calculator

Most goal-based calculators on this site pick a lane: a deficit for fat loss, a surplus for muscle gain. Body recomposition asks for both at once, which is a genuinely harder target, and no single validated formula exists for it. This calculator instead builds around the two levers the evidence actually supports.

What This Calculator Measures

This gives you a calorie target and a protein target designed to support simultaneous fat loss and muscle retention or growth. It does not replace a training program, resistance training is what makes recomposition possible in the first place.

Step 1: Determine Your TDEE

You can either enter your TDEE directly, along with your body weight for the protein target, or let us estimate it from your stats using the same Mifflin-St Jeor and activity-multiplier method used by our TDEE Calculator. If you also enter your current body fat percentage, the estimate uses a lean-mass equation instead, BMR = 370 + 21.6 × lean mass (kg), multiplied by the same activity factor.

Step 2: Apply a Small Deficit

Rather than a large deficit, we apply a smaller one, roughly 10 to 20% below your TDEE. Aggressive deficits work against simultaneous muscle building, so recomposition trades speed for a better shot at holding onto, or gaining, muscle while losing fat.

Calorie target = TDEE × (0.80 to 0.90)

Step 3: Set a Protein Target

We set protein at 1.6 to 2.2 g per kg of bodyweight per day, roughly 0.7 to 1 g per lb, the range with the strongest support for building muscle with resistance training³ ⁴. In a calorie deficit, needs may be at the top of this range or a little above. A review for lean, dieting bodybuilders suggested 2.3 to 3.1 g per kg of lean mass¹, and in a randomized trial of young men in a marked energy deficit, 2.4 g per kg led to more lean mass gain and fat loss than 1.2 g per kg². We also break this into four servings, since one large daily number is harder to act on mid-day. If you carry a lot of body fat, a target based on your full weight can run high, because fat tissue needs little protein. Using a lower reference weight, such as your goal weight, gives a more realistic number⁸.

Protein target (g/day) = Weight (kg) × 1.6 to 2.2

In a meta-analysis of 49 trials, protein above about 1.6 g per kg a day added no further gain in fat-free mass during resistance training³. A review of per-meal protein suggested four servings of 0.4 to 0.55 g per kg to reach 1.6 to 2.2 g per kg a day⁴.

How This Calculator Computes Your Result

Enter your stats and training status above, using either path from Step 1. We apply the deficit and protein formulas, then adjust the messaging in your result based on your training status, since recomposition is more realistic for some starting points than others.

Step 4: Factor In Body Fat and Training Status

Recomposition is most realistic for beginners, returning trainees, or people with higher body fat percentages, they can often lose fat and build muscle at the same time. It’s still possible for lean, already-trained individuals, but progress is typically much slower, which we reflect in your result based on your training status.

A 2020 review found recomposition has also been shown in resistance-trained people, not only in beginners or people with overweight, and named progressive resistance training and evidence-based nutrition as the two key factors⁵.

Worked Example

A 30-year-old man who is 5 ft 10 in, weighs 180 lb and exercises 3 to 5 days a week (moderate activity) has an estimated TDEE of 2,763 calories a day. His recomposition target is 2,210 to 2,487 calories a day, 80 to 90% of TDEE. His protein target is 131 to 180 g a day (1.6 to 2.2 g per kg of his 81.6 kg), or about 4 servings of 33 to 45 g.

Training to Go With the Numbers

The American College of Sports Medicine suggests that novices train 2 to 3 days a week with loads they can lift for 8 to 12 reps, and intermediate lifters 3 to 4 days a week. Once you can do one or two reps more than your target at a given weight, it suggests raising the load by 2 to 10%⁶.

What Rate to Expect

For natural bodybuilders preparing for a contest, a review recommends losing about 0.5 to 1% of body weight per week to keep as much muscle as possible¹. In a trial in elite athletes who strength trained four times a week, eating about 19% less than usual and losing about 0.7% of body weight per week increased lean mass by 2.1%, while eating about 30% less left lean mass unchanged⁷. That slower approach is close to the 10 to 20% deficit this calculator uses.

Because weight can stay flat while fat drops and muscle rises, and body composition measurements have their own error⁵, track waist, photos and training performance over months, not just the scale.