Connecting Your Withings Scale

Weight is the simplest piece of data to measure and the easiest to track badly. One weigh-in a week, taken at any old time, says nothing. A daily weigh-in, taken under the same conditions and read as a rolling average, says a great deal. A connected scale settles the question of regularity: you step on it, the rest happens by itself.

What weight is used for in the tracker

Two uses, no more. Power-to-weight in the mountains. Vertical speed is computed in metres per hour, but the effort it costs depends on what you are carrying up, yourself included. Following how weight moves across a season sheds light on the vertical speed curves and on year-to-year comparisons. Context for the bad weeks. Rapid weight loss in the middle of a heavy block is a signal, in the same way as a flagging heart rate variability. The tracker concludes nothing on your behalf, it puts the data in front of you at the right moment.

The tracker has no diet-tracking function, sets no weight target and passes no judgement on your curve. It records a measurement and displays it.

Step 1 — Set up the scale

If you have not already, set your scale up with the Withings app: it must be linked to your account and sending its weigh-ins to the Withings cloud. The tracker reads that account, not the scale. Weigh yourself under the same conditions: in the morning, after going to the toilet, before drinking or eating, without clothes. Two kilos of difference between a morning and an evening weigh-in have no physiological meaning.

Step 2 — Authorise the tracker

The tracker does not use a copy-paste token for Withings, but a proper authorisation, through OAuth.

1. Settings tab, Tracking equipment section.
2. Tick Withings smart scale.
3. Click Connect Withings. You leave for a Withings page.
4. Sign in and approve access to the weight measurements. That is the only permission requested.
5. You come back to the tracker, the connection is live.

The authorisation can be revoked at any time from your Withings account, and the tracker never asks for your password: it does not see it.

What the ticked box does, exactly

Many GPS watches record a weight in the session file, the one you entered once in the watch settings and that has not moved since. Without the box, that frozen weight overwrites the day's measurement at every session import. Box ticked, the scale has authority. On days when Withings has a weigh-in, session imports no longer touch the weight. On other days, the weight coming from the files is still used, for want of anything better.

What happens next

• The tracker reads the weigh-ins, and nothing else. No body composition, no blood pressure, none of the other devices on your Withings account.
• Reading is one-way. Nothing is ever written into your account.
• The authorisation renews itself in the background. There is nothing to redo periodically.
• A weight entered by hand in the tracker takes priority over everything else: you keep the last word.

If the curve looks wrong

A gap of several days. Check in the Withings app that the weigh-ins are indeed there: if the scale did not transmit, the tracker has nothing to read. Two people on the same scale. Withings scales can tell several users apart, but the attribution is done by weight and can get it wrong when two profiles are close. Correct it in the Withings app, the correction comes through at the next sync. Values jumping a kilo at random. Look at the time of the weigh-ins. It is almost always a matter of conditions, not of the scale.

And without a connected scale?

The tracker accepts manual entry, and one weigh-in a week taken on the same day at the same time beats a connected scale used any old how. The connection does not replace regularity.