The method
When your trend goes flat
By Joshua Nichvolodoff · Fact-checked against sources November 2, 2026 · Next review due November 2, 2027
Clinical review: not yet reviewed by a clinician. How review works · Editorial policy
Sometimes the trend line goes flat for a few weeks. This guide explains exactly what Light Years means by "flat", what that can and can't tell you, and when it's worth raising with your prescriber.
What "flat" means in Light Years
Light Years calls your trend flat when it has moved less than 0.5% of your weight over the last 21 days — and only when you have at least 6 weigh-ins spread across 14 or more of those days. Fewer readings than that, and it says it needs more logs instead.
What it can't tell you
A flat line describes your logged numbers. It can't tell you why the line is flat, what is changing underneath, or whether your treatment is working. It isn't a diagnosis and it isn't a prediction. For why single readings bounce around, see why the daily scale lies.
Right after a dose change
For 14 days after you start or change a dose, Light Years doesn't call the trend flat. That is a design choice so a short stretch isn't over-read — not a statement about what a dose change will or won't do.
When it's worth a conversation
This guide describes how Light Years works. It is general information, not medical advice.
Light Years draws this smoothed line from your own weigh-ins, on your device. Open my tracker or browse the other guides.
Changes to this page
- — Retitled "When your trend goes flat"; removed uncited claims about plateaus and post-dose-change pauses; now explains exactly what Light Years measures.
- — First published.
Substantive corrections are also logged at corrections.