What you must do to avoid losing records
In the past it was common to find the tedious problem that the activity data of the Apple Watch was directly linked to it without synchronization of any kind, causing the data to be completely lost when doing a format. However, this was fixed over the years and it is now possible to have sync with iCloud for data relating to watch health measurements and activity rings.
And it is not even necessary to make a backup of the Apple Watch. In the case of these copies, they are not made as such but are made automatically when making the iPhone. Activity data is kept synchronized as long as the “Watch” option is enabled on the iPhone, found in Settings> your name> iCloud. Even if you reset the clock, you can keep that activity and health data.
Therefore, the necessary requirement to not lose anything is to have this function activated. And if the option does not appear, it is likely that you will have to update software iPhone and / or watch. Remember that to have the latest version of iOS you must go to Settings> General> Software update. In the case of watchOS, you can follow the same route from the watch or from the Watch app on the iPhone by going to the ‘My Watch’ tab and then to General> Software update.
Problems and other very frequent questions about it
If you have made sure that the synchronization of the Watch is enabled in iCloud and yet the activity rings still do not appear in the registry, do not worry. When you finish setting up a Watch, there are many actions that are taking place in the background and that information has probably not been loaded yet, so you will have to be patient and even restart the iPhone and the clock at some point to see if it starts to load everything well.
What if buy a new Apple Watch don’t worry about that data either. Even if the watch model that you are going to release is different from the one you had, the data will be kept thanks to the iCloud synchronization. Therefore you will not have any problem for the new records to be added to the ones you already had. And if they do not appear at the beginning, it is due to the same reasons that we discussed in the previous paragraph.
The only data that could be unrecoverable are those that were recorded several years ago when Apple had not enabled syncing via iCloud. If you restored the Watch when that function was not there yet, unfortunately you will no longer be able to recover them.