> For the complete documentation index, see [llms.txt](https://docs.january.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.january.ai/rest-api/weight-logs.md). # Weight logs Record an end user's body weight and read back one weight per day. Each operation acts on one end user ([End-user identity](/rest-api/api-overview.md#end-user-identity)). Client-token scopes: `weight_logs:write` to create; `weight_logs:read` to list. ## Units and limits Send each weight as `{ "value": …, "unit": … }` in one of these units: | Unit | Accepted value per log | | ---- | ---------------------- | | `lb` | 10–1,000 | | `kg` | 4.5–453.6 | * A weight is stored and returned in the unit it was sent in. * `created_at` is when the weight was measured ([Days and timezones](/rest-api/api-overview.md#days-and-timezones)). Omit it to log the weight now. * Every measurement is kept, but the list shows one weight per local calendar day: the one with the latest `created_at`. A measurement with a later `created_at` on the same day replaces what that day shows; a backdated one earlier that day doesn't. * The list covers `start_date` to `end_date` (both inclusive, in `timezone`), oldest first. Days without a weight are absent, and an empty list is a valid result. * The list returns at most 100 days; when more match, you get the most recent 100, so move `end_date` back to read older days. `start_date` can be at most five years before today in `timezone`; an earlier date fails with `400 date_range_too_large`. * Creating a log is not idempotent. A retried create records the measurement twice, and the list then shows it once. * Weight logs have no ID and cannot be updated or deleted. To change what a day shows, log a newer measurement for that day. {% openapi src="" path="/v1.2/weight-logs" method="post" %} {% endopenapi %} {% openapi src="" path="/v1.2/weight-logs" method="get" %} {% endopenapi %}