# LeanBody

> Photo-based body composition analysis. Returns body fat percentage, lean mass, fat-free mass index (FFMI), and NHANES cohort percentile from four user-submitted photographs. $5 once, no subscription, no accounts.

LeanBody is a single-purpose web app at leanbody.io. Users submit four physique photographs (front flexed, front relaxed, back flexed, back relaxed) and a frontier multimodal vision model returns a body composition analysis. Body fat percentage is delivered to one decimal place. Results are scored against NHANES 2017-20 DXA reference data, sex-stratified. Photos are deleted from storage on completion. Results live in the user's browser only and auto-delete after 48 hours. Not a medical device.

## Core pages

- [Home](https://leanbody.io/): Product overview, spectrum of body composition bands, pricing.
- [Scan flow](https://leanbody.io/scan): Where users enter their stats, take or upload four photographs, and run an analysis.
- [FAQ](https://leanbody.io/faq): Accuracy, photo requirements, privacy posture, refunds, and pricing.
- [Privacy](https://leanbody.io/privacy): Data handling, photo retention, results retention, payment processor, contact.
- [Pricing (machine-readable)](https://leanbody.io/pricing.md): Structured pricing for AI agents.

## Pricing

- $5 USD per scan, paid once via Stripe.
- No subscription, no accounts, no recurring charges.
- Refund issued on request to hello@leanbody.io.

## Methodology

- Vision model: frontier multimodal LLM (Anthropic Claude family) with adaptive thinking and structured output.
- Inputs: four photographs of the subject — front flexed, front relaxed, back flexed, back relaxed — plus self-reported sex, height, weight, age.
- Reference cohort: NHANES 2017-20 DXA whole-body scans, sex-stratified.
- FFMI calculation: lean mass in kilograms divided by height in metres squared. Band thresholds cited to Kouri, Pope, Katz, Oliva (1995).
- Output fields: body fat percentage, lean mass, fat mass, FFMI and band, archetype classification, written analysis, symmetry and aesthetic scores, cohort percentile.
- Not a medical device. Not intended for clinical or diagnostic use.

## Privacy

- Photos: uploaded to ephemeral blob storage for the duration of analysis only, then deleted.
- Results: stored exclusively in the user's browser localStorage; auto-cleared after 48 hours.
- Accounts: none. No login, no email collection beyond the optional Stripe receipt.
- Database: none. No persistent server-side store of user-identifiable data.
- Tracking: Vercel Analytics for anonymous traffic counts; no personal-data tracking.

## Comparison context

- Versus DEXA scans: DEXA is the radiologic gold standard at $80-150 per scan and ~30 minutes per appointment. LeanBody is approximate — useful for tracking trend, not for absolute clinical-grade values.
- Versus bioimpedance smart scales: BIA estimates body fat from electrical impedance, which is hydration-sensitive and varies meaningfully session-to-session. LeanBody offers a more stable read at the cost of requiring photographs.
- Versus skinfold calipers: Calipers are operator-dependent and hard to self-administer. LeanBody removes the operator.

## Contact

- Email: hello@leanbody.io