# What is my body recomposition goal?

Splits your weight into fat and lean mass and finds your weight at a goal body fat percent after gaining muscle, the fat to lose, the weeks it takes, and a protein range.

- Page: https://www.acalculator.org/health/body-recomposition-calculator
- JSON spec: https://www.acalculator.org/health/body-recomposition-calculator.json
- Version: 993781297715

## Default answer

Example with the default inputs (Weight 180 lb, Body fat now 25%, Goal body fat 15%, Lean mass to gain 5 lb, Fat loss per week 1 lb): At 15% body fat your goal weight is 164.7 lb, after losing 20.3 lb of fat in about 20.3 weeks.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| weight | Weight | Your body weight now. |
| bf | Body fat now | Your body fat percent now, from a scan, calipers or the body fat calculator. |
| goal | Goal body fat | The body fat percent you want to reach. |
| gain | Lean mass to gain | Muscle you plan to add, in pounds or kilograms. 0 keeps your lean mass. |
| rate | Fat loss per week | How much fat you plan to lose a week. CDC suggests about 1 to 2 lb of weight a week. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| goalLb | Goal weight | Lean mass after the gain ÷ (1 − goal body fat). |
| goalKg | Goal weight (kg) | The goal weight in kilograms. |
| loseLb | Fat to lose | Fat mass now − fat mass at the goal weight. |
| loseKg | Fat to lose (kg) | The fat to lose in kilograms. |
| weeks | Weeks to goal | Fat to lose ÷ fat loss per week. |
| fatLb | Fat mass now | Weight × body fat percent ÷ 100. |
| fatKg | Fat mass now (kg) | The fat mass in kilograms. |
| leanLb | Lean mass now | Weight − fat mass. |
| leanKg | Lean mass now (kg) | The lean mass in kilograms. |
| proteinLow | Protein per day, from | 1.62 g per kg of body weight now (Morton and others, 2018). |
| proteinHigh | Protein per day, to | 2.2 g per kg of body weight now (Morton and others, 2018). |

## Method

Fat mass = weight × body fat ÷ 100; lean mass = weight − fat mass; goal weight = (lean mass + lean gain) ÷ (1 − goal ÷ 100); fat to lose = fat mass − goal weight × goal ÷ 100; weeks = fat to lose ÷ fat loss per week; protein = 1.62 to 2.2 g × weight now in kg.

## Assumptions

- Body fat percents are as you type them; a scan, calipers and a tape measure can differ by several points.
- Lean mass is everything that is not fat. The lean mass you gain is added to it, and none of it is lost on the way.
- Fat comes off at the steady rate you type. Real progress is uneven; CDC suggests losing about 1 to 2 lb a week.
- Protein: 1.62 g per kg a day is where extra protein stopped adding muscle in the Morton (2018) meta-analysis; about 2.2 g per kg is its upper estimate.
- This is for information only and is not medical advice.

## Worked examples

1. weight = 81.646627, bf = 25%, goal = 15%, gain = 2.267962, rate = 0.453592 gives fatLb = 45, leanLb = 135, goalLb = 164.705882, loseLb = 20.294118, weeks = 20.294118, proteinLow = 132.267535, proteinHigh = 179.622579. Source: Morton RW and others. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 2018;52:376–384 (1.62 g/kg/day; ~2.2 g/kg/day to maximise gains), https://pmc.ncbi.nlm.nih.gov/articles/PMC5867436/; CDC, Steps for Losing Weight (about 1 to 2 pounds a week), https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html.
2. weight = 80, bf = 20%, goal = 15%, gain = 0, rate = 0.25 gives fatKg = 16, leanKg = 64, goalKg = 75.294118, loseKg = 4.705882, weeks = 18.823529. Source: CDC, Steps for Losing Weight (about 1 to 2 pounds a week), https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html.
3. weight = 70, bf = 30%, goal = 25%, gain = 2, rate = 0.5 gives goalKg = 68, loseKg = 4, weeks = 8, proteinLow = 113.4, proteinHigh = 154. Source: Morton RW and others. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 2018;52:376–384 (1.62 g/kg/day; ~2.2 g/kg/day to maximise gains), https://pmc.ncbi.nlm.nih.gov/articles/PMC5867436/.

## FAQ

### What is body recomposition?

Losing fat and gaining lean mass (mostly muscle) at the same time, so your body fat percent falls even if the scale moves little. It usually pairs strength training with enough protein and a small calorie deficit.

### How is my goal weight found?

Your lean mass stays (plus any you gain), and fat makes up the goal percent of the new weight: goal weight = lean mass ÷ (1 − goal body fat). At 180 lb and 25% fat, lean mass is 135 lb; with 5 lb more at 15% fat, the goal weight is 140 ÷ 0.85 = 164.7 lb.

### How much fat do I need to lose?

Your fat mass now less the fat mass at the goal weight. In the example: 45 lb − 164.7 × 0.15 = 20.3 lb. At 1 lb a week that takes about 20 weeks.

### How much protein do I need for body recomposition?

A 2018 meta-analysis of strength training studies (Morton and others) found that extra protein stopped adding muscle at about 1.62 g per kg of body weight a day, and suggested up to about 2.2 g per kg. For 180 lb (81.6 kg), that is 132 to 180 g a day.

### How fast should I lose fat?

CDC notes that people who lose about 1 to 2 lb a week are more likely to keep it off. When you are also building muscle, a slower pace is common.

### Why does the page say my goal needs no fat loss?

If the goal body fat is not below your body fat now, or you plan to gain so much lean mass that it alone brings you to the goal, there is no fat to lose. Lower the goal or the lean mass to gain.

## Sources

- Morton RW, Murphy KT, McKellar SR and others. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine 2018;52:376–384 (breakpoint 1.62 g/kg/day; ~2.2 g/kg/day to maximise gains). https://pmc.ncbi.nlm.nih.gov/articles/PMC5867436/ (retrieved 2026-10-02)
- Centers for Disease Control and Prevention, Steps for Losing Weight (a gradual, steady pace of about 1 to 2 pounds a week). https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html (retrieved 2026-10-02)
- NIST Special Publication 811, Appendix B (1 lb = 0.45359237 kg exactly). https://www.nist.gov/pml/special-publication-811 (retrieved 2026-10-02)