Metabolic Fitness Index: Open, Transparent Score

A transparent 0 to 100 metabolic score from a standard blood panel, your waist-to-height ratio and resting heart rate, with the full formula and weights shown.

  • 4 cited sources
  • Calculates in your browser
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From your blood panel

Fill in what you have and leave the rest blank — the score uses whatever you give it and says how complete it is. All five appear on a standard panel.

Your answer

Appears here as you enter your details. No demo figures — the number is yours, or it is nothing.

Baseline

Know all your numbers

BMI, resting rate, daily burn, eating target, macros, body fat, waist ratios, heart-rate zones and your fitness age: 15 in all. Answer once, see them together, and stop whenever you like.

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Methodology

The Metabolic Fitness Index is an open composite index (v1.0.0). Unlike the scores buried inside proprietary wearables, everything about it is published: the inputs, the sub-score mappings, the weights, and the evidence tier of each input. You, or anyone, can reconstruct the number exactly.

Each input is mapped to a 0 to 100 sub-score (higher = more favourable) using a clamped linear scale between documented anchor points, then combined as a weighted average:

InputWeightTierSub-score anchors (0 → 100)
Time in range30%T250% → 90%
Glucose stability (%CV)20%T245% → 20%
Average glucose (GMI)20%T27.5% → 5.0%
Waist-to-height15%T10.60 → 0.40
Resting heart rate15%T290 → 50 bpm

The anchor points come from recognised references, the international CGM consensus (time in range ≥70%, %CV < 36%), ADA A1C bands for GMI, the 0.5 waist-to-height boundary, and typical adult-to-athletic resting heart rates. They are self-tracking anchors, not diagnostic thresholds. Full detail on the house methodology (normalisation, weighting, versioning) is on the index methodology page.

If you leave an input blank, the index renormalises across what you provided and flags reduced confidence, rather than guessing a value.

Interpreting your result

Read the breakdown, not just the headline. The radar and table show which markers are pulling your score up or down, that's where the useful information is. A single number is only a summary; the point of publishing the sub-scores is so you can see what to work on, framed as a modifiable lever rather than a verdict.

Track your own trend over weeks and months. Because the weights and mappings are fixed and versioned, a change in your score reflects a real change in your inputs, not a moving goalpost.

Limitations

  • This is a transparent self-tracking construct, not a medical test, and it has not been validated against health outcomes.
  • The sub-score anchors are reasonable but chosen by us; different anchors would give different numbers. They are published so you can judge them.
  • CGM-derived inputs inherit CGM's limitations, and for people without diabetes the value of optimising glucose metrics is uncertain (see the CGM metrics tool).
  • Any concern about your metabolic health belongs with a clinician and proper testing, not a self-tracking score.

Sources

Pull the receipts, 4 cited sources

FitTools · sources

  1. 01 NICE NG28 / WHO 2011: HbA1c diagnostic thresholds — 42 mmol/mol (non-diabetic ceiling) and 48 mmol/mol (diabetes)
  2. 02 NICE NG246: waist-to-height ratio bands — 0.4 to 0.49 healthy, 0.5 to 0.59 increased, 0.6+ high
  3. 03 Zhu Y, et al. The association of the triglyceride-to-HDL cholesterol ratio with insulin resistance in White European and South Asian men and women. PLOS One (sex-specific mmol/L cut-points)
  4. 04 PubMed: HOMA-IR, fasting insulin and glucose as an insulin-resistance surrogate

Every formula cited ✓

Frequently asked questions

What is the Metabolic Fitness Index?
It is an open, transparent composite score (0 to 100) that combines six metabolic markers into one number, with the full formula, weights and evidence tiers shown on the page. Unlike the scores inside proprietary wearables, nothing is hidden and you can reconstruct exactly how it was calculated.
Where do I get the inputs?
HbA1c, fasting glucose, fasting insulin, triglycerides and HDL all appear on a standard blood panel, including the one FitTools offers. Waist and height you can measure with a tape; resting heart rate comes from a morning pulse or a wearable. If you have uploaded a blood test to your dashboard, the calculator fills those fields in for you.
What if I do not have all of them?
Enter what you have. The index needs any three of its six inputs and renormalises the weights across whatever is present, marking the result as reduced confidence so you can see it is based on a partial picture. A tape measure, a pulse and one blood marker are enough to start.
Why did this stop asking for CGM data?
Version 1 was built on continuous-glucose-monitor metrics, time in range, glucose variability and GMI, and required all of them, so anyone without a CGM got no score at all. Version 2 uses a standard blood panel instead. GMI is itself a CGM-derived estimate of HbA1c, so a measured HbA1c is not a compromise, it is better evidence of the same thing.
Is a high score good?
Higher is more favourable by the index's design. But it is a self-tracking construct, not a medical test. It has not been validated against health outcomes and it cannot diagnose anything. Use it to track your own trend over time, and take any result outside a normal range to a clinician.
Is my data private?
The score is computed in your browser. Blood results themselves live in your account and never on the device.

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