{
  "story_id": "1ac3076b8bff0eb985aeb15ef3dcae0d",
  "desk": "drm3",
  "revision": 1,
  "published_at": "2026-09-02T05:31:22.000Z",
  "content_hash": "07d9d2122c5fe9c56d06a224aa7f661c966c17f03926932c4e2677d3fe74587e",
  "hash_basis": "sha256 over `headline\\ndek\\nprose`, plus `\\n` + the canonical citations JSON when any source is placed, plus `\\n#blog` for blogs",
  "basis": {
    "headline": "Study finds popular smartwatches overestimate calorie burn",
    "dek": "Independent testing reveals popular smartwatches consistently overestimate calories burned during workouts.",
    "prose": "FIU researchers tested four popular fitness watches against gold-standard clinical lab equipment and found they consistently overstated how many calories people burned. [^1]\n\nA study published in PLOS One by researchers at Florida International University compared four smartwatches (Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5, Garmin Forerunner 955) against the COSMED K5 metabolic analyzer during stationary cycling and found the smartwatches consistently overestimated calories burned. [^2]\n\nJason Kostrna, lead author of the study and FIU associate professor of kinesiology and exercise science, stated that users could be off by hundreds of calories each week. [^3]\n\nThe study found that the higher a person's body fat percentage, the greater the error in calorie estimation tended to be. [^4]\n\nThe mean absolute percentage error for calorie estimates was 35.7% for the Apple Watch, 66.5% for the Samsung, and 77.6% for the Garmin. [^5]\n\nTypical errors in calorie estimation landed in the range of about 15% to 25% during the testing. [^6]",
    "cited": "[{\"statement\":\"FIU researchers tested four popular fitness watches against gold-standard clinical lab equipment and found they consistently overstated how many calories people burned.\",\"source\":\"Medical Xpress\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T21:40:07.000Z\",\"publisher_count\":1,\"sources\":[\"Medical Xpress\"]},{\"statement\":\"A study published in PLOS One by researchers at Florida International University compared four smartwatches (Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5, Garmin Forerunner 955) against the COSMED K5 metabolic analyzer during stationary cycling and found the smartwatches consistently overestimated calories burned.\",\"source\":\"동아일보\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-02T05:31:22.000Z\",\"publisher_count\":1,\"sources\":[\"동아일보\"]},{\"statement\":\"Jason Kostrna, lead author of the study and FIU associate professor of kinesiology and exercise science, stated that users could be off by hundreds of calories each week.\",\"source\":\"Medical Xpress\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T21:40:07.000Z\",\"publisher_count\":1,\"sources\":[\"Medical Xpress\"]},{\"statement\":\"The study found that the higher a person's body fat percentage, the greater the error in calorie estimation tended to be.\",\"source\":\"Medical Xpress\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T21:40:07.000Z\",\"publisher_count\":1,\"sources\":[\"Medical Xpress\"]},{\"statement\":\"The mean absolute percentage error for calorie estimates was 35.7% for the Apple Watch, 66.5% for the Samsung, and 77.6% for the Garmin.\",\"source\":\"동아일보\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-02T05:31:22.000Z\",\"publisher_count\":1,\"sources\":[\"동아일보\"]},{\"statement\":\"Typical errors in calorie estimation landed in the range of about 15% to 25% during the testing.\",\"source\":\"Medical Xpress\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T21:40:07.000Z\",\"publisher_count\":1,\"sources\":[\"Medical Xpress\"]}]",
    "kind": "news"
  },
  "receipt_verify": "Ed25519 over the dot-joined string `slice_hash.cursor_from.cursor_to.view.view_version.row_count`; public_key and sig are base64url of the raw 32-byte key / 64-byte signature",
  "receipt": null,
  "receipt_note": "this revision predates receipt-keeping (before v0.37.0); the filed row lives in the record",
  "generation_chain": {
    "wire": {
      "stream": "fountain_news",
      "story_id": "390241968be1cb5c82fc7b9a79118601",
      "thread_id": "96c3bd634efa55420313337ad7a86169",
      "thread_label": "Apple Watch Series 8",
      "novelty": "UPDATE",
      "content_hash": "97f9b2901112824a40c4c4d97f9482316020d64048994a7fca2b83ae6f02e2f6",
      "last_published_at": "2026-09-02T05:31:22.000Z",
      "read_receipt": {
        "slice_hash": "59f5a8749a4dca30048c68e8154a042a926a8ae31704c66f356f5dde65ee4368",
        "cursor_from": "eyJ0cyI6IjIwMjYtMDktMDJUMDU6MDE6MzAuMDAwMDAwWiIsImlkIjoiMjBmYjc1ZmU1YWViMTQxZmZjNDc4MTMzOTUxNWE0ZmEiLCJ2IjoiMSJ9",
        "cursor_to": "eyJ0cyI6IjIwMjYtMDktMDJUMDU6NTY6MTEuMDAwMDAwWiIsImlkIjoiOTM2OWUyMWM3Y2M0OTBkMmQ4NmMwMGJiNWI2OWJjZDEiLCJ2IjoiMSJ9",
        "view": "v_fountain_news",
        "view_version": "1",
        "row_count": 100,
        "window_days": 3,
        "bytes_scanned": 12017721,
        "credits": 8,
        "price_per_100_rows": 8,
        "sig": "I6xJ31U73f1HmIvmOQTnf1SG5IAVMjX1dkmfgoyBPAjtZJcGArwXQ7wjlJNE9oQRea2qHRlCtuUvGTfpbUFIDw",
        "public_key": "bMUigy8O0jOnBxQ4Sc-5lwhIZ8LQVAhxMbR7qESVuUE",
        "signer_path": "lakehouse/data-extract/v1",
        "alg": "Ed25519",
        "signed": true
      }
    },
    "written_at": "2026-09-02T22:36:30.861Z"
  },
  "cited_facts": [
    {
      "statement": "FIU researchers tested four popular fitness watches against gold-standard clinical lab equipment and found they consistently overstated how many calories people burned.",
      "source": "Medical Xpress",
      "instrument": "News",
      "claim_key": null,
      "published_at": "2026-09-01T21:40:07.000Z",
      "publisher_count": 1,
      "sources": [
        "Medical Xpress"
      ]
    },
    {
      "statement": "A study published in PLOS One by researchers at Florida International University compared four smartwatches (Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5, Garmin Forerunner 955) against the COSMED K5 metabolic analyzer during stationary cycling and found the smartwatches consistently overestimated calories burned.",
      "source": "동아일보",
      "instrument": "News",
      "claim_key": null,
      "published_at": "2026-09-02T05:31:22.000Z",
      "publisher_count": 1,
      "sources": [
        "동아일보"
      ]
    },
    {
      "statement": "Jason Kostrna, lead author of the study and FIU associate professor of kinesiology and exercise science, stated that users could be off by hundreds of calories each week.",
      "source": "Medical Xpress",
      "instrument": "News",
      "claim_key": null,
      "published_at": "2026-09-01T21:40:07.000Z",
      "publisher_count": 1,
      "sources": [
        "Medical Xpress"
      ]
    },
    {
      "statement": "The study found that the higher a person's body fat percentage, the greater the error in calorie estimation tended to be.",
      "source": "Medical Xpress",
      "instrument": "News",
      "claim_key": null,
      "published_at": "2026-09-01T21:40:07.000Z",
      "publisher_count": 1,
      "sources": [
        "Medical Xpress"
      ]
    },
    {
      "statement": "The mean absolute percentage error for calorie estimates was 35.7% for the Apple Watch, 66.5% for the Samsung, and 77.6% for the Garmin.",
      "source": "동아일보",
      "instrument": "News",
      "claim_key": null,
      "published_at": "2026-09-02T05:31:22.000Z",
      "publisher_count": 1,
      "sources": [
        "동아일보"
      ]
    },
    {
      "statement": "Typical errors in calorie estimation landed in the range of about 15% to 25% during the testing.",
      "source": "Medical Xpress",
      "instrument": "News",
      "claim_key": null,
      "published_at": "2026-09-01T21:40:07.000Z",
      "publisher_count": 1,
      "sources": [
        "Medical Xpress"
      ]
    }
  ],
  "note": "A signature proves who filed this and that it has not changed since. It never makes a claim true."
}