Why photos at all
The scale moves in tenths and the mirror lies by the hour. A photo taken the same way every week is the slowest and most honest record there is.
The catch is that progress photos are the most private thing a person can put in an app. This guide is about keeping them useful without giving them away.
Same pose, same light, same distance
Stand in the same spot, face the same direction, and keep the phone at the same height each time. A doorway or a tiled wall makes a good reference.
Daylight from the side beats a ceiling lamp. Pick a time of day you can repeat, and take the photo before breakfast if the comparison matters to you.
In Undiet a pose guide lines you up and fires the shutter when you match it, so the weekly photo takes a minute and lines up with the last one.
Cut out, not cropped
A photo with the room in it is hard to compare with another room. Undiet removes the background on the device, so every photo sits on the same plain ground.
The cut out is done by the phone, not a server. Nothing is sent anywhere to make it happen.
Comparing two dates
Pick any two photos. The earlier one fades over the later one as a ghost, anchored on the same landmarks, and a slider moves between them.
This is the quiet kind of progress, the kind you notice by looking rather than by reading a number. It also works the other way, which is honest too.
Where the photos live
The vault is a folder inside the app, behind Face ID or your passcode, not your camera roll. Photos are not uploaded, not backed up by us and not used to train anything.
Delete the app and the photos go with it. That is the point: nobody, including us, can see them.
Never posted
There is no share button for photos, no before and after post, and no option to switch one on. The community is text only.
If you want to show a photo to someone, that is a choice you make with your own phone in your hand, outside the app.
How often
Weekly is enough. Daily photos add noise, and a month between photos loses the thread.
The free app keeps the last 30 days in the vault;Pluskeeps the whole history, so the ghost compare can reach back to the first one.
Read the fine print
Theprivacy policysays the same in legal words: photos are processed and stored on your device only. Thephotospage shows how the vault works.
If you are deciding between diets as well,Find my dietis five taps and asks for no photo, no weight and no email.