{
  "id": "body-recomposition",
  "version": "993781297715",
  "status": "published",
  "name": "Body Recomposition Calculator",
  "question": "What is my body recomposition goal?",
  "summary": "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.",
  "category": "health",
  "subcategory": "body",
  "url": "https://www.acalculator.org/health/body-recomposition-calculator",
  "markdown": "https://www.acalculator.org/health/body-recomposition-calculator.md",
  "kind": "function",
  "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."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "weight": {
        "title": "Weight",
        "description": "Your body weight now.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 30,
        "maximum": 350
      },
      "bf": {
        "title": "Body fat now",
        "description": "Your body fat percent now, from a scan, calipers or the body fat calculator.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 3,
        "maximum": 70
      },
      "goal": {
        "title": "Goal body fat",
        "description": "The body fat percent you want to reach.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 3,
        "maximum": 70
      },
      "gain": {
        "title": "Lean mass to gain",
        "description": "Muscle you plan to add, in pounds or kilograms. 0 keeps your lean mass.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0,
        "maximum": 50
      },
      "rate": {
        "title": "Fat loss per week",
        "description": "How much fat you plan to lose a week. CDC suggests about 1 to 2 lb of weight a week.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0.01,
        "maximum": 2
      }
    }
  },
  "outputs": {
    "goalLb": {
      "label": "Goal weight",
      "description": "Lean mass after the gain ÷ (1 − goal body fat).",
      "format": "number"
    },
    "goalKg": {
      "label": "Goal weight (kg)",
      "description": "The goal weight in kilograms.",
      "format": "number"
    },
    "loseLb": {
      "label": "Fat to lose",
      "description": "Fat mass now − fat mass at the goal weight.",
      "format": "number"
    },
    "loseKg": {
      "label": "Fat to lose (kg)",
      "description": "The fat to lose in kilograms.",
      "format": "number"
    },
    "weeks": {
      "label": "Weeks to goal",
      "description": "Fat to lose ÷ fat loss per week.",
      "format": "number"
    },
    "fatLb": {
      "label": "Fat mass now",
      "description": "Weight × body fat percent ÷ 100.",
      "format": "number"
    },
    "fatKg": {
      "label": "Fat mass now (kg)",
      "description": "The fat mass in kilograms.",
      "format": "number"
    },
    "leanLb": {
      "label": "Lean mass now",
      "description": "Weight − fat mass.",
      "format": "number"
    },
    "leanKg": {
      "label": "Lean mass now (kg)",
      "description": "The lean mass in kilograms.",
      "format": "number"
    },
    "proteinLow": {
      "label": "Protein per day, from",
      "description": "1.62 g per kg of body weight now (Morton and others, 2018).",
      "format": "number"
    },
    "proteinHigh": {
      "label": "Protein per day, to",
      "description": "2.2 g per kg of body weight now (Morton and others, 2018).",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "weight": 81.6466266,
      "bf": 25,
      "goal": 15,
      "gain": 2.2679618500000003,
      "rate": 0.45359237
    },
    "outputs": {
      "goalLb": 164.7058823529412,
      "goalKg": 74.70933152941177,
      "loseLb": 20.294117647058822,
      "loseKg": 9.205256920588235,
      "weeks": 20.294117647058822,
      "fatLb": 45,
      "fatKg": 20.41165665,
      "leanLb": 135,
      "leanKg": 61.23496995,
      "proteinLow": 132.267535092,
      "proteinHigh": 179.62257852
    },
    "text": "At 15% body fat your goal weight is 164.7 lb, after losing 20.3 lb of fat in about 20.3 weeks."
  },
  "examples": [
    {
      "given": {
        "weight": 81.6466266,
        "bf": 25,
        "goal": 15,
        "gain": 2.2679618500000003,
        "rate": 0.45359237
      },
      "expect": {
        "fatLb": 45,
        "leanLb": 135,
        "goalLb": 164.7058823529412,
        "loseLb": 20.294117647058822,
        "weeks": 20.294117647058822,
        "proteinLow": 132.267535092,
        "proteinHigh": 179.62257852
      },
      "source": "hand calculation in content.mdx: (135 + 5) ÷ 0.85 = 164.71 lb; 45 − 164.71 × 0.15 = 20.29 lb; 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"
    },
    {
      "given": {
        "weight": 80,
        "bf": 20,
        "goal": 15,
        "gain": 0,
        "rate": 0.25
      },
      "expect": {
        "fatKg": 16,
        "leanKg": 64,
        "goalKg": 75.29411764705883,
        "loseKg": 4.705882352941177,
        "weeks": 18.823529411764707
      },
      "source": "hand calculation in content.mdx: 64 ÷ 0.85 = 75.29 kg; 16 − 75.29 × 0.15 = 4.71 kg; ÷ 0.25 = 18.8 weeks; CDC, Steps for Losing Weight (about 1 to 2 pounds a week), https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html"
    },
    {
      "given": {
        "weight": 70,
        "bf": 30,
        "goal": 25,
        "gain": 2,
        "rate": 0.5
      },
      "expect": {
        "goalKg": 68,
        "loseKg": 4,
        "weeks": 8,
        "proteinLow": 113.4,
        "proteinHigh": 154
      },
      "source": "hand calculation in content.mdx: lean 49 + 2 = 51 ÷ 0.75 = 68 kg; 21 − 17 = 4 kg; 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/"
    }
  ],
  "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)"
  ],
  "related": [
    "body-fat",
    "ffmi",
    "protein",
    "tdee",
    "calorie-deficit"
  ],
  "changelog": []
}