# Three Tissue

> An explainer for DEXA (dual-energy X-ray absorptiometry) body-composition scan reports. Paste one or more reports under a date - the report's region table as printed (Region | Fat | Lean | BMC | Total, in kg, lb or g) or label: value lines. The page maps bone, lean and fat on a front-view body by region, left against right, draws a sparkline per measurement across up to six scans, works out ALMI, the lean and fat mass indexes, the android / gynoid ratio and the change since the last scan, and flags numbers against published reference cutoffs and rough rules of thumb. A metered read explains each tissue's trend and each region in plain words with a clear / watch / ask-a-clinician verdict; a second metered run grades the person's plan for the next scan, action by action, by strength of evidence. Not a diagnosis. https://three-tissue.skillsafe.ai/

## What it does

- Free, in the browser (scankit.js, bodyview.js): one scan per date header (`## 2026-06-02`), then the region table as printed (a header row naming the columns, one row per region; a row with no header is left out rather than guessed) or `label: value unit` lines copied from the report - total mass, body fat %, fat mass, lean mass, bone mineral content, visceral fat (mass or area), android and gynoid %, left and right arm and leg lean and fat, trunk lean and fat, BMD, T-score and Z-score (the lowest of each is kept with its site). kg, lb and g are converted; unknown lines are listed and left out.
- Worked out per scan: arm and leg lean mass and ALMI (over height squared), lean and fat mass indexes, the android / gynoid ratio, the left-right lean gap per limb, bone / lean / fat as shares of the body, and the change since the scan before (with the share of any weight loss that was lean mass).
- Flags. Ask a clinician: a T-score at or below -2.5 (the WHO osteoporosis range), a Z-score at or below -2.0, ALMI under the EWGSOP2 (2019) cutoff of 5.5 kg/m2 for women or 7.0 for men. Watch: a T-score between -1 and -2.5, lean mass over a quarter of the weight lost, fat up while lean fell, a limb gap over 10% (a rule of thumb), visceral fat over about 1,000 g or 100 cm2 (a rough line; ranges differ). Notes: changes under about 1 kg treated as scan noise (an estimate), a gap under 8 weeks, an android-leaning fat pattern, missing sex, height or regional values.
- Metered task `read` (from the skill health-coach): bone, lean and fat each with a trend (up, down, flat, single) and a short read; arms, legs and trunk each balanced, lopsided or no-data; one to five findings (ask, watch or note); one to four questions to take to a clinician, coach or the scan provider; a clear / watch / ask verdict.
- Metered task `plan` (from the skill doctorg): the person's plan for the next scan, item by item, each kept, changed or dropped, at most two additions, each with a GRADE-style evidence grade (strong, moderate, low, very low); rough targets labelled as estimates; when to rescan; cautions; a keep / adjust / rethink verdict counted from its own changes and drops. It answers the read's findings when the read was run first.
- The page holds both replies to its own numbers: each tissue trend against the measured change, each region against the measured left-right gap, every clinician flag carried through, no internal field names in prose, and the plan verdict against its own count.

## Limits

- An explainer, not medical advice or a diagnosis; flagged numbers belong with a clinician. The page reads only what is pasted - it does not see the scan images, and different scanners and software report slightly differently.
- Cutoffs are published reference values (WHO, EWGSOP2) or rough rules of thumb, labelled as such on the page.
- Exports: Markdown (scans table, figures, flags, the read and the plan), a scans CSV with every value and the page's figures, and the body map as SVG.

## Sources

- Built on the SkillSafe skills @h1an1/health-coach (body-composition tracking and plain-language reading of health measurements): https://skillsafe.ai/skill/@h1an1/health-coach and @glebis/doctorg (evidence-based health research with GRADE-inspired evidence ratings): https://skillsafe.ai/skill/@glebis/doctorg
- Why now: Rising Trends' fitness trends list for October 2026 puts "Dexa Scans" at about 201K monthly searches, up 49% year on year, and "Sarcopenia" up 22%: https://www.risingtrends.co/trends/fitness-trends-2026
- API: https://three-tissue.skillsafe.ai/api.html