Health Calculator
Body Recomposition Calculator
Work out the daily calories and macronutrients to lose fat while gaining or holding muscle. Enter your details to get a BMR and TDEE estimate, a recomposition calorie target, and a protein, fat and carbohydrate breakdown with the full arithmetic shown.
Body Recomposition Calculator
Daily calorie and macro targets for losing fat while building muscle
Moderate exercise 3–5 days per week
A mild deficit of 100–300 kcal below maintenance, favouring fat loss.
Enables lean-mass-based macro targets
Results
Enter your details, then click Calculate Targets
Understanding Body Recomposition
Body recomposition is the pursuit of two goals that normally oppose each other: losing fat while gaining muscle. Fat loss requires an energy deficit; building muscle is easiest in a surplus. Recomposition threads between them with a small adjustment — either a mild deficit or maintenance — paired with high protein and consistent resistance training.
That narrow margin is the whole method. Cut too hard and the training quality and recovery that drive muscle growth collapse, leaving you smaller but not leaner. Sit too far above maintenance and fat accumulates alongside the muscle. The 100–300 kcal band is deliberately modest for exactly this reason.
The consequence is that scale weight becomes almost useless as a progress marker. Fat lost and muscle gained largely cancel out, so the number can sit still for weeks while your measurements and photographs change. Judge recomposition by the tape, the mirror and the loads you lift, not the scale.
Body Recomposition Formulas
Four steps run from your measurements to a macro split.
1. BMR — Mifflin-St Jeor
Basal metabolic rate, the energy burned at complete rest:
2. TDEE
Total daily energy expenditure — BMR scaled for how much you move:
3. Recomposition Calories
4. Macronutrients
Protein and fat are set from body weight; carbohydrates take what remains:
Activity Multipliers and Their Effect
The activity factor is the single largest lever on your target. For the male in Example 1 — BMR 1,777.5 kcal — the choice spans more than 1,200 calories a day:
| Activity Level | × | TDEE | Recomp Target |
|---|---|---|---|
| Sedentary | 1.2 | 2,133 | 1,933 |
| Lightly Active | 1.375 | 2,444 | 2,244 |
| Moderately Active | 1.55 | 2,755 | 2,555 |
| Very Active | 1.725 | 3,066 | 2,866 |
| Extremely Active | 1.9 | 3,377 | 3,177 |
Most people overestimate here. Three or four gym sessions a week alongside a desk job is moderately active, not very active. If your weight is not moving as the numbers predict, an inflated activity factor is the usual culprit — drop one level before cutting calories further.
Body Weight or Lean Mass for Macros?
Protein targets set per kilogram of body weight work well at moderate body fat, but they drift high as body fat rises — fat tissue has little protein requirement of its own. Basing the same multipliers on lean mass corrects that. For an 80 kg person, the gap widens steadily:
| Body Fat | Lean Mass | Protein (LBM) | Protein (BW) | Diff |
|---|---|---|---|---|
| 10% | 72.0 kg | 158 g | 176 g | 18 g |
| 15% | 68.0 kg | 150 g | 176 g | 26 g |
| 20% | 64.0 kg | 141 g | 176 g | 35 g |
| 25% | 60.0 kg | 132 g | 176 g | 44 g |
| 30% | 56.0 kg | 123 g | 176 g | 53 g |
| 35% | 52.0 kg | 114 g | 176 g | 62 g |
Figures are the 2.2 g/kg upper bound. Note that body fat percentage affects only the macro split here — it does not enter the Mifflin-St Jeor equation, so BMR and TDEE are unchanged either way.
Mild Deficit or Maintenance?
Both are legitimate recomposition settings; they differ in which side they favour. Since protein and fat are fixed by body weight, the entire difference lands on carbohydrates — for the Example 1 male, 50 grams:
| Goal | Calories | Protein | Fat | Carbs |
|---|---|---|---|---|
| Mild deficit | 2,555 | 152 g | 72 g | 325 g |
| Maintenance | 2,755 | 152 g | 72 g | 375 g |
Pick the deficit when fat loss leads or body fat is higher; pick maintenance when you are already lean, strength has stalled, or muscle gain is the priority. Alternating between them across a training block is common and sensible.
Benefits of Using the Body Recomposition Calculator
Example Calculations
Three profiles worked through end to end:
Example Scenario 1 — Male, Mild Deficit
Age 28, 80 kg, 178 cm, Moderately Active, mild deficit.
BMR = (10 × 80) + (6.25 × 178) − (5 × 28) + 5
BMR = 800 + 1,112.5 − 140 + 5 = 1,777.5 kcal/day
TDEE = 1,777.5 × 1.55 = 2,755 kcal/day
Recomp calories = TDEE − 300 to TDEE − 100 = 2,455 to 2,655 kcal
Midpoint target = 2,555 kcal/day (a 200 kcal deficit)
Protein = 1.6–2.2 g/kg × 80 kg = 128–176 g · Fat = 0.8–1.0 g/kg × 80 kg = 64–80 g
At midpoints: Protein 152 g (608 kcal) · Fat 72 g (648 kcal)
Carbs = 2,555 − 608 − 648 = 1,299 kcal = 325 g
Result: 2,555 kcal — 152 g protein, 72 g fat, 325 g carbs
Example Scenario 2 — Female, Mild Deficit
Age 32, 65 kg, 165 cm, Lightly Active, mild deficit.
BMR = (10 × 65) + (6.25 × 165) − (5 × 32) − 161
BMR = 650 + 1,031.25 − 160 − 161 = 1,360.25 kcal/day
TDEE = 1,360.25 × 1.375 = 1,870 kcal/day
Recomp calories = 1,570 to 1,770 kcal · Midpoint target = 1,670 kcal
Protein = 1.6–2.2 g/kg × 65 kg = 104–143 g · Fat = 0.8–1.0 g/kg × 65 kg = 52–65 g
At midpoints: Protein 123.5 g (494 kcal) · Fat 58.5 g (527 kcal)
Carbs = 1,670 − 494 − 527 = 650 kcal = 162 g
Displayed rounded: Protein 124 g · Fat 59 g · Carbs 162 g
Result: 1,670 kcal — 124 g protein, 59 g fat, 162 g carbs
Example Scenario 3 — Macros From Lean Mass
Male, age 35, 90 kg, 180 cm, Very Active, 22% body fat.
BMR = 1,855 kcal/day · TDEE = 1,855 × 1.725 = 3,200 kcal/day
Recomp calories = 2,900 to 3,100 kcal · Midpoint target = 3,000 kcal
Lean body mass = 90 × (1 − 0.22) = 70.2 kg
Protein on lean mass = 1.6–2.2 g/kg × 70.2 = 112–154 g
Protein on body weight = 1.6–2.2 g/kg × 90 = 144–198 g
At 22% body fat the lean-mass figure is 44 g lower at the top end
Result: 3,000 kcal — 133 g protein, 63 g fat, 474 g carbs
Treat These as a Starting Point
Predictive BMR equations carry roughly a 10% error for any individual, and activity multipliers are coarse by nature — together they can be several hundred calories off. Run the numbers for two to four weeks, track your weight and measurements, then adjust from what actually happens rather than trusting the estimate. Recomposition also rests on things no calorie figure captures: progressive resistance training, protein spread across the day, and adequate sleep. Without the training stimulus, a mild deficit is simply a slow diet. These figures are general guidance, not medical or dietary advice.
Frequently Asked Questions
- What is body recomposition?
- Body recomposition means losing fat and gaining or maintaining muscle at the same time, so your weight may barely move while your shape changes considerably. It contrasts with a traditional cut or bulk, where weight moves clearly in one direction. Because the two goals pull against each other, recomposition uses a smaller calorie adjustment than either approach alone.
- How do you calculate calories for body recomposition?
- Start with BMR from the Mifflin-St Jeor equation, multiply by an activity factor to get TDEE, then either hold at TDEE or subtract a mild 100–300 kcal. The deficit stays small deliberately: a large one compromises the training and recovery that muscle gain depends on, which is what separates recomposition from ordinary fat loss.
- What is the Mifflin-St Jeor equation?
- It estimates basal metabolic rate, the energy you burn at complete rest. For males, BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5. For females the same expression ends with − 161. It is generally considered the most accurate of the common predictive equations, though it still carries roughly a 10% error for any given individual.
- How much protein do I need for body recomposition?
- Between 1.6 and 2.2 grams per kilogram of body weight per day. Protein is the macronutrient that matters most here, because it supports muscle retention and growth while in a deficit. For an 80 kg person that is 128 to 176 grams daily, best spread across three or four meals rather than concentrated in one.
- Should protein be based on body weight or lean mass?
- Body weight works well at moderate body fat, but lean mass is more sensible once body fat is high, since fat tissue does not need feeding. At 80 kg and 20% body fat the top-end target drops from 176 g to 141 g when calculated on lean mass. Enter a body fat percentage to switch between the two bases.
- How are carbohydrates calculated?
- Carbs are the remainder. Protein and fat are set first from body weight, their calories are subtracted from the daily target, and whatever is left is divided by 4 kcal per gram. This ordering is deliberate — protein and fat have minimum requirements, whereas carbohydrate intake is flexible and fills the remaining energy budget.
- Can recomposition work for everyone?
- It works best for beginners, people returning after a layoff, and those carrying higher body fat, all of whom can build muscle and lose fat simultaneously with relative ease. Trained lifters near their genetic ceiling find it much slower and often do better alternating dedicated gaining and cutting phases.
- Why does the scale barely move during recomposition?
- Because fat loss and muscle gain roughly offset one another in weight terms. This is the expected outcome, not a sign of failure, and it is why scale weight is a poor way to track recomposition. Progress photos, tape measurements, and strength in the gym tell you far more than the number on the scale.
- Should I pick mild deficit or maintenance?
- Choose the mild deficit when fat loss is the priority or body fat is higher. Choose maintenance when you are already relatively lean, when strength is stalling, or when you want to prioritise muscle gain. Many people alternate between the two across a training block rather than committing to one indefinitely.
- How long does body recomposition take?
- Longer than either cutting or bulking alone — meaningful change typically takes three to six months, and visible results often lag by six to eight weeks. Because the calorie adjustment is small, the weekly changes are small too. Reassess your targets every four to six weeks, or whenever your weight shifts by three kilograms or more.