{
  "registry": "KnowYourPrime Evidence Registry",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Credit KnowYourPrime and link to the finding URL."
  },
  "fields": {
    "devices": "Devices this finding names, including models it says it does not cover. What was actually tested is in scope.applies_to; exclusions are in scope.does_not_cover.",
    "evidence": "Studies by role: anchor (the rating rests on it), conflicting, null_result, supporting.",
    "industry_ties": "Device-maker ties listed in Europe PMC metadata: author_affiliations names makers an author lists as an affiliation, funders names makers listed as funding. stated_ties holds ties a paper states only in its own conflict, funding or acknowledgement text, each read from that statement and worded to say only what it says. Sources are Europe PMC metadata, funding printed in the abstract, and those reviewed statements. An empty list means no tie was found there, not that the study is independent: many papers have no open full text to read. Metadata, not a judgment of the study. checked false means no Europe PMC metadata was available."
  },
  "id": "KYP-ER-0010",
  "version": "1.1",
  "reviewed": "2026-10-24",
  "url": "https://knowyourprime.com/evidence-wearable-calorie-accuracy",
  "title": "Wearable Calorie and Energy Expenditure Accuracy",
  "question": "Are consumer wearables accurate enough to trust for calories burned?",
  "measurement": "Calories (energy expenditure)",
  "devices": [
    "Apple Watch",
    "Fitbit",
    "Garmin",
    "Samsung",
    "Polar"
  ],
  "rating": {
    "label": "Uncertain",
    "code": "uncertain",
    "definition": "Evidence is conflicting, inconsistent, or difficult to interpret.",
    "rule_version": "1.4",
    "rule_reasons": [
      "Multiple supporting studies are consistent with the core relationship.",
      "An anchor study was assessed but its own reported finding runs contrary to this claim, so the evidence is treated as unsettled rather than affirming.",
      "An anchor study was assessed but its own reported finding runs contrary to this claim, so the evidence is treated as unsettled rather than affirming.",
      "An anchor study was assessed but it does not test this claim’s core relationship directly, so the evidence is treated as unsettled rather than affirming.",
      "An anchor study was assessed but its own reported finding runs contrary to this claim, so the evidence is treated as unsettled rather than affirming.",
      "At least one unresolved conflicting study bears on the core claim, capping the rating until reconciled.",
      "Some evidence conflicts on secondary points that do not change the core direction."
    ]
  },
  "conclusion": "No. Every major review finds calorie estimates inaccurate across brands; across 65 validation studies, the error exceeded 30 percent for every brand tested, even on devices whose heart rate and step counts are accurate.",
  "reasoning": [
    "A calorie figure is a model built on heart rate, movement and personal details, checked against oxygen and carbon dioxide measured in breath. Small errors in each input compound.",
    "All four anchor reviews report negative or unvalidated findings for energy expenditure, and direct comparisons in high-intensity training found trackers underestimating. With every anchor running against the claim, the rule treats it as unsettled and rates it Uncertain; the evidence is consistent that the numbers are not accurate."
  ],
  "key_results": [
    {
      "text": "In a review of 158 publications across nine brands, energy expenditure was not accurate for any brand.",
      "source": "doi:10.2196/18694",
      "source_url": "https://doi.org/10.2196/18694",
      "source_citation": "Fuller et al., JMIR mHealth and uHealth, 2021"
    },
    {
      "text": "A systematic review of 65 validation studies found mean absolute percentage error for energy expenditure exceeded 30 percent for every brand tested.",
      "source": "doi:10.2196/30791",
      "source_url": "https://doi.org/10.2196/30791",
      "source_citation": "Germini et al., Journal of Medical Internet Research, 2022"
    },
    {
      "text": "During high-intensity functional training in 47 adults, four of five trackers significantly underestimated total energy expenditure against a portable metabolic analyzer, and all five differed from it.",
      "source": "doi:10.1080/02701367.2019.1603989",
      "source_url": "https://doi.org/10.1080/02701367.2019.1603989",
      "source_citation": "Morris et al., Research Quarterly for Exercise and Sport, 2020"
    }
  ],
  "scope": {
    "applies_to": "Active and total calorie estimates from consumer wrist wearables compared with indirect calorimetry.",
    "does_not_cover": "Heart rate and step accuracy, which are better; research-grade accelerometers; calorie intake."
  },
  "limitations": [
    "Error varies by activity, so a single percentage does not describe any one workout.",
    "Error in clinical groups, such as manual wheelchair users, can be larger, and few studies test them."
  ],
  "evidence": {
    "anchor": [
      {
        "key": "doi:10.1007/s40279-024-02077-2",
        "title": "Keeping Pace with Wearables: A Living Umbrella Review of Systematic Reviews Evaluating the Accuracy of Consumer Wearable Technologies in Health Measurement.",
        "first_author": "Doherty",
        "journal": "Sports medicine (Auckland, N.Z.)",
        "year": 2024,
        "url": "https://doi.org/10.1007/s40279-024-02077-2",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.2196/30791",
        "title": "Accuracy and Acceptability of Wrist-Wearable Activity-Tracking Devices: Systematic Review of the Literature.",
        "first_author": "Germini",
        "journal": "Journal of medical Internet research",
        "year": 2022,
        "url": "https://doi.org/10.2196/30791",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.2196/35626",
        "title": "Accuracy and Precision of Energy Expenditure, Heart Rate, and Steps Measured by Combined-Sensing Fitbits Against Reference Measures: Systematic Review and Meta-analysis.",
        "first_author": "Chevance",
        "journal": "JMIR mHealth and uHealth",
        "year": 2022,
        "url": "https://doi.org/10.2196/35626",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.2196/18694",
        "title": "Reliability and Validity of Commercially Available Wearable Devices for Measuring Steps, Energy Expenditure, and Heart Rate: Systematic Review.",
        "first_author": "Fuller",
        "journal": "JMIR mHealth and uHealth",
        "year": 2021,
        "url": "https://doi.org/10.2196/18694",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "conflicting": [
      {
        "key": "doi:10.1038/s41393-020-0427-5",
        "title": "Comparative validity of energy expenditure prediction algorithms using wearable devices for people with spinal cord injury.",
        "first_author": "Shwetar",
        "journal": "Spinal cord",
        "year": 2021,
        "url": "https://doi.org/10.1038/s41393-020-0427-5",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1080/02701367.2019.1603989",
        "title": "Validity of Activity Trackers in Estimating Energy Expenditure During High-Intensity Functional Training.",
        "first_author": "Morris",
        "journal": "Research quarterly for exercise and sport",
        "year": 2020,
        "url": "https://doi.org/10.1080/02701367.2019.1603989",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "supporting": [
      {
        "key": "doi:10.2196/69343",
        "title": "Analysis of a Medically Certified, Wrist-Worn Sensor for the Assessment of Heart Rate and Energy Expenditure During Daily Activities in Patients With Chronic Heart Failure or Coronary Artery Disease and Recreational Athletes: Validation Study.",
        "first_author": "De Lathauwer",
        "journal": "JMIR cardio",
        "year": 2026,
        "url": "https://doi.org/10.2196/69343",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1371/journal.pone.0342543",
        "title": "Comparison of consumer-grade wearable devices with a research-grade instrument for measuring physical activity in a free-living setting.",
        "first_author": "Miwa",
        "journal": "PloS one",
        "year": 2026,
        "url": "https://doi.org/10.1371/journal.pone.0342543",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.3390/s26144486",
        "title": "Consumer Smartwatch Technology in Health and Performance Research: Validity, Limitations, and Real-World Applications.",
        "first_author": "Lepley",
        "journal": "Sensors (Basel, Switzerland)",
        "year": 2026,
        "url": "https://doi.org/10.3390/s26144486",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.2196/83090",
        "title": "Validity of Galaxy Watch for Estimating Energy Expenditure During Intermittent Running: Cross-Sectional Study.",
        "first_author": "Ferreira",
        "journal": "JMIR formative research",
        "year": 2026,
        "url": "https://doi.org/10.2196/83090",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.3390/s25061726",
        "title": "Comparison of Students' Physical Activity at Different Times and Establishment of a Regression Model for Smart Fitness Trackers.",
        "first_author": "Cheng",
        "journal": "Sensors (Basel, Switzerland)",
        "year": 2025,
        "url": "https://doi.org/10.3390/s25061726",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1038/s41598-025-99963-0",
        "title": "Developing and comparing a new BMI inclusive energy expenditure algorithm on wrist-worn wearables.",
        "first_author": "Wei",
        "journal": "Scientific reports",
        "year": 2025,
        "url": "https://doi.org/10.1038/s41598-025-99963-0",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1249/mss.0000000000003721",
        "title": "Leveraging Accelerometry and Heart Rate Data from Consumer Wearables to Predict Physical Activity in Children: A Device Agnostic Approach.",
        "first_author": "Ghosal",
        "journal": "Medicine and science in sports and exercise",
        "year": 2025,
        "url": "https://doi.org/10.1249/MSS.0000000000003721",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1080/17483107.2024.2405895",
        "title": "Validity of a wrist-worn consumer-grade wearable for estimating energy expenditure, sedentary behaviour, and physical activity in manual wheelchair users with spinal cord injury.",
        "first_author": "Bailey",
        "journal": "Disability and rehabilitation. Assistive technology",
        "year": 2025,
        "url": "https://doi.org/10.1080/17483107.2024.2405895",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1371/journal.pone.0331399",
        "title": "Validity of four low-cost smartwatches in estimating energy expenditure during cycling in Chinese untrained women.",
        "first_author": "Liu",
        "journal": "PloS one",
        "year": 2025,
        "url": "https://doi.org/10.1371/journal.pone.0331399",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1177/19417381231175149",
        "title": "Exercise Intensity and Activity Energy Expenditure of Professional Golf Players in Official Competitive Setting.",
        "first_author": "Scalise",
        "journal": "Sports health",
        "year": 2024,
        "url": "https://doi.org/10.1177/19417381231175149",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1123/jpah.2022-0160",
        "title": "Wearable Device Validity in Measuring Steps, Energy Expenditure, and Heart Rate Across Age, Gender, and Body Mass Index: Data Analysis From a Systematic Review.",
        "first_author": "Musa",
        "journal": "Journal of physical activity & health",
        "year": 2023,
        "url": "https://doi.org/10.1123/jpah.2022-0160",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1080/02640414.2020.1746088",
        "title": "Improving energy expenditure estimates from wearable devices: A machine learning approach.",
        "first_author": "O'Driscoll",
        "journal": "Journal of sports sciences",
        "year": 2020,
        "url": "https://doi.org/10.1080/02640414.2020.1746088",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1249/mss.0000000000001471",
        "title": "Validity of Wearable Activity Monitors during Cycling and Resistance Exercise.",
        "first_author": "Boudreaux",
        "journal": "Medicine and science in sports and exercise",
        "year": 2018,
        "url": "https://doi.org/10.1249/MSS.0000000000001471",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1371/journal.pone.0171720",
        "title": "Assessment of laboratory and daily energy expenditure estimates from consumer multi-sensor physical activity monitors.",
        "first_author": "Chowdhury",
        "journal": "PloS one",
        "year": 2017,
        "url": "https://doi.org/10.1371/journal.pone.0171720",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ]
  },
  "evidence_last_evaluated": "Oct 15, 2026",
  "rating_history": [
    {
      "date": "2026-07-20",
      "rating": "Uncertain",
      "from": null,
      "rule_version": "1.4"
    }
  ],
  "versions": [
    {
      "version": "1.0",
      "date": "2026-10-24",
      "rating": "Uncertain",
      "change": "First published."
    },
    {
      "version": "1.1",
      "date": "2026-10-24",
      "rating": "Uncertain",
      "change": "Opening adds the 30 percent error figure with its 65-study base."
    }
  ],
  "research_desk": "https://knowyourprime.com/research-desk-activity#energy-expenditure-validity",
  "related_findings": [
    "https://knowyourprime.com/evidence-wearable-heart-rate-accuracy"
  ],
  "related_articles": [
    "https://knowyourprime.com/does-the-calorie-number-on-your-wearable-mean-anything"
  ],
  "methodology": "https://knowyourprime.com/methodology",
  "citation": "KnowYourPrime Evidence Registry, Finding KYP-ER-0010, version 1.1, reviewed 2026-10-24. https://knowyourprime.com/evidence-wearable-calorie-accuracy"
}