curl --request POST \
  --url https://api.iotools.cloud/v1/tool/body-fat-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "sex": "male",
  "units": "metric",
  "height": "180",
  "waist": "85",
  "neck": "38",
  "hip": ""
}
'

{
  "tool": "body-fat-calculator",
  "tool_version": "1.0.1",
  "outputs": {
    "results": [
      {
        "metric": "Body Fat %",
        "value": "16.1%"
      },
      {
        "metric": "Category",
        "value": "Fitness"
      },
      {
        "metric": "Category Range",
        "value": "14–17%"
      }
    ]
  },
  "credits_used": 3,
  "credits_remaining": null
}