# Reference meals and the next benchmark

The nine original photo fixtures use visually estimated portion ranges.
Reference calories combine those estimates with nutrition densities. Results
therefore describe agreement with those references, not measured calorie truth.
A shared yardstick makes the runs comparable, but uncertain references cannot
establish a reliable real-world accuracy ranking from small differences.

## Source existing documented meals

The next step is to find published meal photos or datasets that already include
measured portion weights and documented calorie and macro references for the
pictured food. Update, October 6, 2026: the Nutrition5k comparison completed on September 18.
Read the findings: https://kcalsnap.com/journal/nutrition5k-calorie-benchmark/
The steps below record the reference-selection requirements.

For each candidate source:

1. Check that the nutrition and portion weights belong to the food actually
   pictured. A recipe's total calories do not establish the amount on a plate.
2. Record the source URL, collection method, cooked or raw state, serving size,
   ingredients and nutrition provenance. Keep reported uncertainty visible.
3. Check licensing and permitted image use before copying or publishing assets.
4. Freeze the reference set before model calls. Keep reference values independent
   of the predictions being evaluated and distinguish new evaluation data from
   examples already used to develop the matcher.

## What to report

Compare portion estimates, nutrition-record choices and whole-meal totals.
Include missing components in plate-level results. Report USDA-matched and
AI-estimated items separately alongside coverage, latency and cost. Different
food groups may have different difficulty, so similar errors alone do not prove
that those nutrition sources are interchangeable.

Published data can have limitations and may have appeared in model training.
Document those limits rather than claiming that a public dataset is unseen.
Measured portions also do not make reference calories exact: recipe calculation,
food composition and nutrition-label uncertainty still matter.