Body Recomposition Calculator

Body recomposition means losing fat and building muscle at the same time. To do it, eat near maintenance, keep protein high (about 1.6–2.2 g per kg of bodyweight) and lift weights regularly. This calculator sets calorie and macro targets for training and rest days: a little above maintenance when you lift, below it when you rest.

How to use this calculator

1. Enter sex, age, weight and height in lb/in or kg/cm.
2. Add your body fat percentage if you know it (from a scan, calipers or a smart scale). Leave it blank if you don't.
3. Pick an activity level that includes your training, and enter how many days a week you lift.
4. Read your maintenance calories (TDEE) and the training-day and rest-day targets for calories, protein, carbs and fat.
5. Follow them for 3–4 weeks, then adjust by 100–200 kcal if your weight moves faster than you want.

How the targets are calculated

1. BMR: Katch-McArdle (370 + 21.6 × lean kg) if you enter body fat, otherwise Mifflin-St Jeor (10 × kg + 6.25 × cm − 5 × age + 5 for men, − 161 for women; Mifflin et al., 1990).
2. Maintenance (TDEE) = BMR × activity factor (1.2–1.725, a common convention; FAO/WHO/UNU physical activity levels run 1.4–2.4 × BMR).
3. Training days: TDEE + 10%; rest days: TDEE − 20% (a practical convention, not a research-derived ratio).
4. Protein 2.2 g/kg (1 g/lb) bodyweight, or 2.6 g/kg lean mass capped at 2.2 g/kg bodyweight; fat 25% of calories on training days and 30% on rest days, inside the 20–35% range the National Academies recommend (with a 0.8 g/kg floor); carbs fill the rest at 4 kcal/g.

Worked examples

In the first example the weekly average is 79 kcal/day below maintenance, a small deficit. In the third, rest-day fat is set by the 0.8 g/kg floor (76 g) rather than 30% of calories, because 30% would fall below that. The second example shows how a lighter, less active person ends up with rest days near 1,539 kcal.

Lifting days and your weekly calorie balance

Because training and rest days differ, the number of lifting days decides whether your week averages a deficit or a surplus.

If you want slightly faster fat loss, lift on fewer days or move your activity level down one step. If you are underweight or struggling to gain strength, the extra training days push you toward a surplus.

Who should recomp vs cut or bulk?

Recomp is easiest for people new to lifting, returning after a break or carrying more body fat. Lean, experienced lifters usually make faster progress with separate bulk and cut phases, though trained people can still recomp slowly (Barakat et al., 2020). If your main goal is a set amount of fat loss by a date, use the weight loss by date calculator instead. For maintenance calories from the newest government equations, see the EER calculator.

Training for a recomp

The food targets only work alongside resistance training. The U.S. Physical Activity Guidelines (2nd edition) advise adults to do muscle-strengthening activity at least 2 days a week, plus 150–300 minutes of moderate aerobic activity. For a recomp, most people lift 3–5 days and aim to add weight or reps over time. If your lifts are not going up, the plan is not working, whatever the scale says. Strength athletes can track progress with our DOTS score calculator.

Common mistakes

• Judging by the scale alone. Muscle gain can hide fat loss. Use waist measurement, photos and strength as well.
• Protein too low. The general adult RDA of 0.8 g/kg is a minimum for health, not a target for building muscle.
• Overestimating activity. Pick the level that matches your whole day, not just your workouts. Most desk workers who lift 3–4 times a week are "moderate" at most.
• Changing targets every few days. Weight fluctuates with water and salt. Give each setting 3–4 weeks.
• Guessing body fat. A wrong body fat number shifts BMR and protein. If you have no measurement, leave it blank.

FFMI

FFMI (fat-free mass index) is lean mass ÷ height², plus 6.3 × (1.8 − height in m) to normalise to 1.8 m (Kouri et al., 1995). In that study, steroid-free male athletes topped out at an FFMI of about 25. The calculator shows it only when you enter body fat.

Health note

These are estimates for healthy adults, not medical or dietetic advice. Talk to a doctor or registered dietitian before changing your diet if you are pregnant or breastfeeding, under 18, have diabetes, kidney disease or another medical condition, take medication that affects appetite or blood sugar, or have a history of disordered eating. Stop and get medical help if you have chest pain, fainting or unusual shortness of breath during exercise.

Frequently asked questions

Sources & method

• Mifflin et al. (1990), Am J Clin Nutr — resting energy equation
• Morton et al. (2018), Br J Sports Med — protein plateau 1.62 g/kg (95% CI 1.03–2.20)
• Jäger et al. (2017), ISSN position stand — protein and exercise
• Helms et al. (2014), JISSN — protein for lean athletes in a deficit
• Kouri et al. (1995), Clin J Sport Med — fat-free mass index
• National Academies — Dietary Reference Intakes for macronutrients (AMDR, protein RDA)
• FAO/WHO/UNU (2001) — Human energy requirements, physical activity levels
• Nutrients (2021) — resting energy equations incl. Katch-McArdle
• Hall (2008), Int J Obes — energy content of weight change
• Barakat et al. (2020), Strength Cond J — body recomposition review
• U.S. HHS — Physical Activity Guidelines for Americans, 2nd edition (top 10 things to know)

Results are estimates for general information. Found an error? It helps everyone — see our methodology.